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Full text of "The elements of refrigeration; a text book for students, engineers and warehousemen"

WORKS OF 
PROFESSOR A. M. GREENE, JR, 

PUBLISHED BY 

JOHN WILEY & SONS, Inc. 



Elements of Heating and Ventilation. 

A Text-book for Technical Students and a 
Reference Book for Engineers. 8vo, vi +324 
pagea, 223 figures. Cloth, $2.50 net. 

Pumping Machinery. 

A Treatise on the History, Design, Construction, 
and Operation of Various Forms of Pumps. 
8vo, vi +703 pages, 504 figures. Cloth, $4.00 net. 

The Elements of Refrigeration. 

A Text-book for Students, Engineers and Ware- 
housemen, vi +472 pages. 6 by 9. 192 figures. 
Cloth, $4.00 net. 

BY SPANGLER, GREENE, AND MARSHALL: 

Elements of Steam Engineering. 

Third Edition, Revised. 8vo, v+296 pages, 
284 figures. Cloth, $3.00. 



THE ELEMENTS 

OF 

REFRIGERATION 

A Text Book for Students, 
Engineers and Warehousemen .-^/ C <*? 



BY 



ARTHUR M. GREENE, JR. 

Professor of Mechanical Engineering, Russell Sage Foundation, Rensselaer 

Polytechnic Institute; Sometime Junior Dean, School of 

Engineering, University of Missouri 



FIRST EDITION 
FIRST THOUSAND 



NEW YORK 

JOHN WILEY & SONS, INC., 

LONDON : CHAPMAN & HALL, LIMITED 
1916 



51162 



Copyright, 1916 

BY 
ARTHUR M. GREENE, JR. 



BRAUNWORTH & CO. 

BOOK MANUFACTURERS 

BROOKLYN. N. V. 



PREFACE 



The aim of the author in preparing this book has been to 
bring together in a logical order the necessary data from which 
to design, construct and operate refrigeration apparatus. He 
has endeavored to describe the apparatus and then to give 
the theoretical discussion of the principles on which the action 
of this apparatus rests. A detailed description of the applica- 
tions of refrigerating machinery, to cold storage and ice making 
is followed by that of other applications. The author has 
freely consulted the Transactions of the American Society of 
Refrigerating Engineers and the bound volumes of Ice and 
Refrigeration, and has gained much information from these 
two excellent publications. Much of the text has been de- 
veloped in teaching this subject for many years. Whenever 
the work of others has been used, credit has been given. The 
author is indebted to many writers whose work he has used 
in the class room and in preparation of his lectures, and to 
the manufacturers of refrigerating apparatus who have given 
data for the preparation of this text. The aim has been to make 
the book complete with the necessary engineering data for 
problem work without reference to other books. 

The author has added a set of problems in the last chapter 
illustrating most of the computations which must be made in 
refrigerating work. The problems illustrate the methods by 
which questions of the engineer may be answered. 

The book is intended for the use of upper class men 
in technical schools, for engineers and those operating re- 
frigerating apparatus. The work presupposes a knowledge of 
thermodynamics and heat engineering. 

The plan of the work has been for a continuous study of 
the book without any omission. The last two chapters are 



iv PREFACE 

intended to give data and methods for actual computations 
and should be used during the course for problem work. Prob- 
lems based on the text should be given with the study of the 
book. These problems should be solved by use of the slide 
rule. 

The author desires to thank his wife, Mary E. Lewis Greene, 
for the aid she has given in the preparation of the manuscript 
and in the reading of proof. He desires to thank those authors, 
publishers and manufacturers who have furnished him with 
data. 

A. M. G., Jr. 
SUNNYSLOPE, TROY, N. Y. 
September i, 1916. 



TABLE OF CONTENTS 



CHAPTER I 

PAGE 

PHYSICAL PHENOMENA AND INTRODUCTION. Early methods, evaporation, 
solution, latent heat, heat of fusion, vaporization under reduced pressure, 
natural ice, compression machines, air, volatile liquid, general principles i 

CHAPTER II 

METHODS OF REFRIGERATION. Natural ice, different systems of cold storage, 
refrigerator cars, air machines, open and closed systems, volatile liquid 
machines, refrigerants, absorption machine, vacuum apparatus, chemical 
methods 8 

CHAPTER III 

THERMODYNAMICS OF REFRIGERATING APPARATUS. Air machine, refrigerating 
effect, cooling, displacement, work, effect clearance, effect friction, incom- 
plete expansion and compression, moisture, vapor machines, temperature- 
entropy charts, Mollier charts, dry and wet compression, absorption 
apparatus, problem, multiple effect 41 

CHAPTER IV 

TYPES OF MACHINES AND APPARATUS. Various machines, cylinders, manip- 
ulating valves, pistons, COz machines, SO- machines, absorption 
apparatus, welding, pipes, fittings, condensers/ separators, receivers, 
coolers, vacuum apparatus, binary refrigeration, cooling towers, nozzles, 
ponds, safety devices '. 109 

CHAPTER V 

HEAT TRANSFER, INSULATION AND AMOUNT OF HEAT. Radiation, convec- 
tion, conduction, transmission, constants, walls, partition?, floors, pipe 
covering, doors, heat from machines, lights, persons, cold storage data.. . 182 

CHAPTER VI 

COLD STORAGE. Purpose, laws, peculiar features of storage for different 
articles, layout of warehouse, construction, arrangement of piping, 



Vi TABLE OF CONTENTS 

PAGE 

special cold storage, amount of insulation, indirect refrigeration, bunkers, 
fans, amount of refrigeration, coil surface, pipe sizes, central stations, 
automatic refrigeration, refrigerator cars, precooling 217 

CHAPTER VII 

ICE MAKING. Can system, plate system, apparatus, flooded system, niters, 
evaporators, raw water system, freezing tanks, expansion coils, curve of 
consumption, storage 269 

CHAPTER VIII 

OTHER APPLICATIONS OF REFRIGERATION. Candy, breweries, blast furnace, 
auditoriums, rinks, ice cream, shaft sinking, drinking water, chemical 
works, dairy, creamery, liquid air 312 

CHAPTER IX 

COSTS OF INSULATION AND OPERATING COSTS. Land, buildings, machinery, 
supplies, dimensions of apparatus, power and performance of plants, 
labor costs, load factors, operating costs, ice data, car data, ice cream 
data, ammonia, carbon dioxide, sulphur dioxide, testing apparatus, 
results of tests 343 

CHAPTER X 

PROBLEMS. Insulation, space, refrigeration for rooms, coil surface, pipe 
length, velocity of brine, bunker coil, fan size, brine main and pump, 
ammonia main, plate plant, refrigeration of plant, ice storage, cost of 
pumping, evaporator, filter, compressor, power, condenser, multiple 
effect, water cooling tower, blast furnace refrigeration, test computations. 407 



ELEMENTS OF REFRIGERATION 



CHAPTER I 
PHYSICAL PHENOMENA AND INTRODUCTION 

THE practice of cooling bodies below the temperature of 
the surrounding atmosphere has been followed for ages. This 
has been done by the evaporation of a liquid as is the practice 
in Mexico and other warm climates, where the liquid to be 
cooled is hung in porous vessels. The evaporation of the liquid 
which percolates through to the outside cools that remaining 
inside. In India, it is stated, evaporation from the surface 
of shallow porous vessels even causes a film of ice to form. 
The solution in water of a salt like saltpetre, or the mixture 
of snow or ice and saltpetre, has been used for centuries to 
abstract heat and cool the liquid resulting, or anything that 
was immersed in it. 

The first method was applied about one hundred and 
fifty years ago in a way differing from that of the ancients. 
It was then found that evaporation of the liquid would occur 
if the pressure were removed, particularly if the liquid were 
ether or some other highly volatile liquid. This evaporation 
would occur at such a low temperature that ice would rapidly 
form on the surface of the vessel containing the boiling liquid 
if the vessel were placed in water. It was also found that 
if the vapor arising from the evaporation of the liquid were 
compressed to a higher pressure than that at which evapora- 
tion took place, it could be condensed again by water at ordinary 
temperature, and the process repeated. 

The property of the substances utilized in these illustrations 



2 ELEMENTS OF REFRIGERATION 

is the property of latent heat. When a body changes its state, 
a certain amount of energy must be absorbed by that body 
to bring about this changed state. To change a body from 
a solid in which the form and volume are fixed and the con- 
dition of the molecules is such that their orbits are fixed, into 
a liquid in which the volume but not the form is fixed, or the 
molecules have orbits which have more freedom, requires the 
addition of energy. The name heat energy, or heat, is applied 
to this. Energy is required to change a body from the liquid 
state to the vapor state in which the form and volume are 
not fixed, since the molecules have free paths. The molecules 
are so far apart that molecular attraction has been broken down. 
The energy required in the case of the fusion of a solid or the 
evaporation of a liquid is used to overcome molecular energy 
of attraction, and for that reason it is potential in form 
within the body. It is not used up in increasing the kinetic 
energy of the particles of the body, and hence there is no change 
of temperature during these additions, and the heat is called 
latent heat. , 

In general, if heat be continuously added to a solid while 
the pressure remains constant, its temperature will rise until 
the point of melting or fusion is reached and then the tem- 
perature will remain constant until the solid is changed to a 
liquid. The temperature of the liquid will then continue to 
rise with the addition of heat until the boiling-point is reached, 
at which point the temperature will remain constant while 
the heat is added, although the liquid will be changing to a 
vapor. The further addition of heat will increase the temper- 
ature of the vapor. 

The previous operations were supposed to take place at 
constant pressure, because to every pressure there corresponds 
a temperature of fusion and a temperature of vaporization. 
These are fixed for definite pressures, and at these pressures 
and temperatures the amount of heat to fuse i Ib. of sub- 
stance, the heat of fusion, and the heat required to vaporize 
i Ib. of liquid, the heat of vaporization, are fixed. Should the 
pressure change, the temperature of these actions would'change. 



PHYSICAL PHENOMENA AND INTRODUCTION 3 

In the ancient way of producing cool liquids, the evap- 
oration which occurred at the outside of the vessel required 
heat, and this was largely supplied from the liquid within. 
The liquid was cooled by the removal of heat. If this removal 
of heat cools the liquid to its freezing-point (fusion-point of 
solid), any further evaporation of the liquid from the surface 
of the vessel would remove heat from the liquid and cause some 
of it to solidify, forming ice if the liquid were water. In the 
case of salt being dissolved, this same kind of energy is needed. 
In this case it is called the heat of solution. To change the 
condition of the molecules of the salt so that the molecular 
forces are overcome, energy is applied, and as this energy comes 
from the liquid, its temperature is lowered. 

In the case of, the vaporization of a liquid under reduced 
pressure, the object of this reduction is to permit the evap- 
oration at such a low temperature that heat may be removed 
from surrounding objects of low temperatures. Water boils 
at 212 F., but if the pressure were reduced to -^V Ib. the tem- 
perature of boiling would be less than 32 F. and with the 
evaporation of some liquid, ice could form. Of course, it must 
be remembered that the evaporation of a liquid can take place 
only if heat is added to it at the boiling-point. If the liquid 
is at the boiling-point and there is nothing from which heat 
can be abstracted, nothing can happen. If it is in contact 
with substances at temperatures below the boiling-point noth- 
ing will happen. For this reason the pressure on the lower 
side must be such that the boiling temperature is below the 
temperature of the body from which it is to abstract heat, and 
when evaporated, the pressure must be raised to a point at 
which the boiling temperature will be above that of the substances 
used to abstract heat. In this latter condition the substances 
will abstract heat from the vapor and condense it. 

These methods have been used for years to obtain cool 
water, to preserve foods and for other purposes. In many 
places, however, this preservation was carried on by the use 
of natural ice harvested in the winter and stored unti! needed 
in warm weather. 



4 ELEMENTS OF REFRIGERATION 

It was about the middle of the last century that the Carre 
Brothers produced commercial machines for the freezing of 
water. Both machines operated to remove heat by vapor- 
ization of a volatile fluid, Edmund Carre evaporating water 
vapor at very low pressures and Ferdinand Carre evaporating 
liquid anhydrous ammonia. These machines were not used 
to produce large quantities of ice, but they produced com- 
mercial quantities. 

The compression type of machine introduced in 1835 by 
Perkins was further developed by Twining, who took out his 
English patent in 1850 and his U. S. patent in 1853. ^ n this 
machine a volatile liquid such as ether, carbon disulphide or 
sulphur dioxide is allowed to flow through a throttle valve into 
a region of such low pressure that the boiling temperature of 
the liquid is low. This liquid will boil by the abstraction of 
heat from the substance around the walls of the chamber in 
which it is placed. The pressure is maintained at a low point 
by the suction of a compressor which removes the vapor as it 
is formed and compresses it to a higher pressure. This pressure 
is high enough to give a temperature of boiling or liquefaction 
higher than that of a water supply. The water will remove 
heat from the vapor and cause its liquefaction. The liquid 
is then passed through the cycle again. In this system the 
liquid and its vapor are kept separate from everything else by 
being contained in a closed system. Such a machine produced 
commercial quantities of ice. 

There is one other method of abstracting heat, which has 
been used for some time. This is the compressed-air method. 
If air is compressed rapidly, its temperature is increased, due to 
the work which has been done upon it. This air may be cooled 
to its original temperature by being passed through pipes 
over which water is allowed to flow, and if this high-pressure 
air is permitted to drive a piston and do work, the work done 
will cause a decrease in~temperature, so that the expanded 
air will be so cold that it will abstract heat from a space or 
room through which it may be passed in pipes or in the open 
on its way to the suction of the compressor. In this case 



PHYSICAL PHENOMENA AND INTRODUCTION 5 

the heat abstracted in the refrigerator and that equal to the 
difference between the works of the compressor and of the 
expander are taken up by the cooling water. In this machine 
the compressor and expander work on the same shaft. 

In all mechanical refrigerating machines the working sub- 
stance is placed in such a condition that it will abstract heat 
from the material of low temperature and after this absorption 
it is placed in such a condition that it will give up this heat 
and that added to operate the process, to a water supply 
at a higher temperature than that of the refrigerator space. 
This is the general principle of all refrigerating machines. 

In the middle of the last century a development of the 
western part of the United States took place, and with it arose 
a desire to ship fruits from the central parts of the country to 
the East. In 1866 refrigerated boxes holding 200 quart baskets 
of strawberries and 100 Ibs. of ice were built. These weighed 
complete 600 Ibs. They proved that fruit could be shipped 
if kept cool. This was done by Parker Earle. In 1868 Davis 
of Detroit proposed to insulate cars to handle beef and fish, 
and in 1872 there were successful experiments. This was the 
beginning of the refrigerated car industry, which has so extended 
that in 1910 there were over 130,000 cars in the United States, 
although only a little over 1000 in Europe. 

The 'Original refrigeration and even a large amount of modern 
refrigeration have been accomplished by ice. The machines 
for the manufacture of the so-called artificial ice, or better 
manufactured ice, have made possible the refrigerating of stores 
or other houses by the use of this apparatus without the em- 
ployment of ice. In these cold-storage warehouses the vol- 
atile liquid may be passed through pipes in the various rooms, 
from which it abstracts heat and vaporizes, or the evaporation 
of the liquid may abstract heat from a strong brine of a very 
low freezing-point. This cold brine is pumped through the 
rooms, removing heat. This latter method is spoken of as the 
cool-brine system of refrigeration, while the former is called 
the direct-expansion system. The method of mechanical refrig- 
eration has made it possible to care for storage in warm countries 



6 ELEMENT^ OF REFRIGERATION 

at a distance from ice fields. It has permitted the refrig- 
eration of certain portions of vessels during long voyages. It 
has also led to the possibility of the cold storage of food 
products. In 1905 it was stated that the value of food prod- 
ucts in cold storage in the United States amounted to over 
$200,000,000, and the investment in refrigerating apparatus 
amounted to over $100,000,000. 

The first long-distance shipment of meats in refrigerators 
on shipboard was in 1873, but it was unsuccessful. In 1875 
successful shipments were made from America to England, 
and in 1880 Australia shipped meat to England. These ship- 
ments have so grown that in 1910 the United Kingdom im- 
ported nearly 13,000,000 carcasses of lamb and mutton and 
over 4,000,000 quarters of beef from South America, New Zealand 
and Australia. In 1904 the United Kingdom paid $45,000,000 
for fruit, of which one-ninth came from the United States. 
In 1910 there were more than 800 vessels equipped for the 
transportation of food products in cold storage. 

From the above the original importance of this mechanical 
refrigeration is seen, but with its development further applica- 
tions have been made and at the present time its use enters 
into many industries. 

Cut flowers are kept for a considerable time, and even trees 
may be held dormant for weeks to prevent budding before trans- 
planting in the spring. Milk and cream may be kept sweet for 
some time by means of refrigeration. In the manufacture of 
wine and beer this apparatus is used to prevent the rise of tem- 
perature as well as to cool hot liquids. In the refining of oils 
the apparatus is used for the removal of certain paraffin products. 
In the ventilation of buildings in warm weather, cooled brine 
may be employed to cut down the humidity of the air as well 
as the temperature. This is applied also in metallurgical oper- 
ations to remove the excess moisture from the air entering a 
blast furnace, as well as to make the air of uniform quality. 
In the manufacture of textiles, in the curing of tobacco and 
in cigar making, in the making of perfumery, in the manu- 
facture of photographic films and other products, as well as 



PHYSICAL PHENOMENA AND INTRODUCTION 7 

in developing, the use of the refrigerating machine or its product 
is indispensable. Even in mining and in excavating the re- 
frigerating machine has been applied: in the first case to cool 
warm excavations, and in the second to freeze a ring of quick- 
sand so that an excavation could be made through this treacher- 
ous material. In theraputics, the value of refrigeration is being 
seen. Mr. W. T. Robinson has stated that he has known of 
hay fever patients being relieved by visiting cold-storage ware- 
houses. 



CHAPTER II 
METHODS OF REFRIGERATION 

THE commercial -methods of refrigeration or the cooling 
of materials and spaces are as follows: 

1. Natural ice; 

2. Air machines; 

3. Compression machines using volatile liquids; 

4. Absorption machines using volatile liquids; 

5. Evaporation; 

6. Chemical methods. 

In describing these methods and in illustrating them, the 
endeavor has been made to show certain well-known types of 
apparatus so that the student may study actual forms of 
machines. The peculiarities of the apparatus must be noted 
and studied in the examples chosen, since these are found 
in most apparatus for this purpose. The examples taken are 
those known to the author, and represent good practice. There 
are many machines built of value equal to that of those shown, 
and in buying machinery comparison must be made between 
all parts before deciding which machine is the best. 

In the application of natural ice, which is that employed 
in the common refrigerator, the ice is used to cool the air in 
contact with it, and then this air, becoming heavy, drops to 
the bottom of the refrigerated space, displacing warmer air, 
which rises to the ice chamber, where it is cooled by the melt- 
ing of a proper amount of ice. Fig. i illustrates the form 
of refrigerator built by the McCray Company. The ice is 
introduced on one side of the ice box and the air is circulated 
downward to the lower part of that side, rising to the provision 
side of the refrigerator. The walls of the refrigerator are 

8 



METHODS OF REFRIGERATION 



9 



made of several thicknesses of materials. As shown, it con- 
sists of oak, sheathing paper, poplar or some other lumber, 
sheathing paper, mineral wool, sheathing paper, lumber, felt 
and opal glass, nine layers in all. This makes a well-insulated 
box. 

In Fig. 2 the Jackson system of cold storage is shown. In 




U 

FIG. i. McCray Refrigerator. 

this the cold air falls around the ice and drops into the cold- 
storage room, after which, on being heated, it ascends to the 
ice room. The ice is supported on a slat floor and the drip is 
caught in the necessary pans, from which it is removed by 
pipes. The columns are properly protected against this drip. 
The air leaving the ice chest is saturated with moisture at the 
temperature of the ice, and as it descends into the warmer 
portions of the box its moisture capacity is increased, so that 



10 



ELEMENTS OF REFRIGERATION 



there will not be any deposit of moisture from the air. As 
the air passes over the goods, there is, if anything, a tendency 
to take up moisture, and when the air enters the ice chest this 




FIG. 2. Jackson System of Cold Storage. 

moisture is removed as the temperature falls. This means 
additional ice melting. This is not a loss, as the evaporation 
in the box abstracts heat and this increases the cooling effect 
at this point, for which, of course, ice is melted later. The 



METHODS OF REFRIGERATION 



11 



methods of insulating floors, walls, and ceilings are to be exam- 
ined by the student in the figures shown. 

In Fig. 3 the arrangement of the Dexter system, in which 




FIG. 3. Dexter System of Cold Storage. 

the air from the ice room does not enter the cold-storage room, 
is shown. This drawing is self-explanatory. In all these 
arrangements the water from the melting ice may be taken 



12 



ELEMENTS OF REFRIGERATION 




METHODS OF REFRIGERATION 13 

through pipes placed in the cold-storage room. This water 
is cold and will remove some heat by being warmed to the 
temperature of the storage room. In this way the apparatus 
is made more efficient. Fresh air for ventilation may be intro- 
duced by a duct leading to the outside through the ice room. 

Fig. 4 illustrates the method of cooling refrigerator cars. 
In these ice is introduced at each end of the car, and the cir- 
culation of air, in at the top and out at the bottom, cools the 
air and maintains a low temperature. The refrigerator car 
shown has been recently built by the American Car and Foundry 
Co. for the Illinois Central R. R. for their express service. The 
cars are 50 ft. long and have a capacity of 40 tons. They weigh 
75,700 Ibs. each. They are supported on steel frames. The 
car proper is built of yellow-pine framing supported on steel 
under-framing. The insulation is made up of lumber, insulating 
material and spaces arranged as shown in the figure. The 
door section is shown on the right of the cross-section as well 
as the ice chute on the left. The ice is packed in collapsible 
compartments at each end of the car, and rests on a rack or 
support at the bottom. This is the Bohn collapsible ice box. 
From it the air is deflected by curved slats into the refrig- 
erated space. It passes through a screen to prevent the en- 
trance of solid bodies. The rack at the bottom folds up into 
the end of the car and the slatted front folds up to the roof. 
The end of the car is protected from the ice by the horizontal 
strips shown in the cross-section. Ice is charged through the 
upper doors. Sometimes the ice is broken in a crusher before 
being introduced and sometimes ice blocks are used. The space 
for ice is about 3 ft. long, 6| ft. from ice support to roof, and 
8 ft. wide. This would hold about 3 tons of ice at each end. 
There is an insulating plug in each of the four ice hatches, 
and the covers are]equipped with adjustable latches to give ven- 
tilation when needed. The water is drained from the bottom. 

In the above installations, temperatures of 36 to 38 may 
be obtained in warm weather. When lower temperatures are 
desired, resort must be made to mixtures of salt and ice. The 
following table, given by T. Bowen in Bulletin 98, U. S. De- 



14 



ELEMENTS OF REFRIGERATION 



partment of Agriculture, gives the temperature resulting from 
mixtures of ice and salt: 



Per cent salt in mixture by weight . . o 5 
Temperature of mixture 32 27 



10 15 20 25 
20 ii 1.5 10 



60 


























































\ 






























\ 


























B.tu.perLb.ofSalt. 

fe & 






\ 






























\ 






























\ 


X, 




























X 


X 
















Heat of Solution, 

S 8 I 
















\ 


\ 






























^ 


^ 






























" 


^--^ 


^-^ 






















































































5f 10* 15* 20* 25* 30* a 
Weight of Salt aa a* of Ice used 



FIG. 5. Curve of Heat of Fusion of One Pound of Salt for Different Amounts 
of Salt. (J. T. Bowen.) 

The heat of solution of the salt varies from 58 B.t.u. to 
16 B.t.u., depending on the concentration of the salt. On 
melting the ice, which requires 143.4 B.t.u., and dissolving 
the salt, which requires a variable amount, the total heat 
required will be the sum of that due to the salt solution and the 
melting of the ice. 



METHODS OF REFRIGERATION 



15 



For different percentages of salt added to water the heat 
of solution is given by the curve of Fig. 5. Since the heat 
of solution of salt is less than that of ice, the heat of 
melting of a mixture of ice and salt per pound of mixture 



B.t.u. per Pound of Mixture of Ice and Salt 
1 g g S g 














































































































































\ 


^X, 






























\ 


^ 






























\ 


Xs 






























\ 


^ 






























\ 


^ 






























^ 


x^ 






























"^ 


\ 


























































5* 10* r>* 20?< 25* 30* 38 



Weight of Salt as a Percentage of the Ice used. 

FIG. 6. Heat of Melting One Pound 'of Ice and Salt in Different Proportions. 
(], T. Bowen.) 

decreases as the amount of salt increases. This is shown in 
Fig. 6. 

The specific heat of the salt brine and of ice must be known 
to make the necessary calculations for the heat removed and 
the temperature of the mixtures. The specific heat of the 
brine for different percentages of salt is given in Fig. 7. 



16 ELEMENTS OF REFRIGERATION 

The specific heat of ice at absolute temperature T, is given by 



as determined by Dickinson and Osborne. 



i.oo 



0.90 



10* 15* ).; 25# 

Salt as a Percentage of the Water used. 



30 J f 



35* 



FlG 7 Specific Heat of Salt Brine for Different Amounts of SaH.) (Bowen.) 

By mixing ice and salt together low temperatures may be 
obtained for chilling or freezing. The ice must be brought 
into intimate contact with the salt, and for that reason the 
ice is broken into small pieces. This of course necessitates 
the ice filling a containing vessel, which is placed in the storage 
room, although in some cases air is drawn through the mix- 



METHODS OF REFRIGERATION 



17 



ture. This is difficult, as the mixture sometimes freezes into 
a solid mass. Then it becomes necessary to increase the 




FIG. 8. Diagram of Cooper Gravity Brine Circulating System. 

'surface used to refrigerate the room. Certain patented methods 
have been proposed. 



18 ELEMENTS OF REFRIGERATION 

The Cooper gravity brine circulation system is shown 
diagrammatically in Fig. 8. In this ice is broken in a crusher 
and delivered to the top of the storage house, or it may be 
crushed at the top after it is delivered. Here it is mixed 
with salt and introduced into the ice tank. 

This tank contains a set of coils filled with brine, and con- 
sequently the mixture of ice and salt removes heat from the 
brine, cooling it to the temperature of the mixture. After 
this is done there will be no further melting except that due 
to the heat loss from the tank. When, however, the valves 
controlling the brine system are opened, the heavy cold brine 
will tend to fall to the lowest part of the. system, bringing 
warm brine to the top and producing a strong circulation. 
The brine then removes heat from the refrigerator rooms, 
being passed through coils on the walls or ceiling. The ice tanks 
are about 10 ft. high. The lower part is not very active, as 
the brine in the coils is cooled by the time it reaches this 
point, and the salt brine from the melting ice cannot take up 
any more salt, as its temperature is too low. The ice and 
salt must be thoroughly mixed before introduction, as the 
salt is apt to cake. When a new charge is to be introduced, 
the ice in the tank should be stirred with a stick to prevent 
any caking. The brine formed from the ice melting, is of 
value for cooling in that it is at a low temperature. It may 
be passed through the refrigerated rooms in pipes, or it may 
be used at other points. Cooper claims that two men can 
handle 4 tons of ice per hour in charging this system and 
that 4 tons per day will cool a storehouse of 40 cars capacity 
in average summer weather. The amount required in any 
case may be computed from the heat losses in the storage 
house. 

Air machines are operated in the following manner: Air 
is compressed in a cylinder A from a pressure pi to a pressure 
p 2 . The air is discharged from the compressor through a set 
of self-acting mushroom valves or by a slide valve, and is 
passed into cooling coil B, which is surrounded by water. In 
this coil the air which has been heated by the compressor is 



METHODS OF REFRIGERATION 



19 



cooled almost to the temperature of the water, and by this 
cooling it is reduced in volume and is passed into the expansion 
cylinder C This is mounted in tandem with the compressor, 
as in the Lightfoot machine, or beside the compressor attached 
to the same shaft as in the Allen Dense Air machine. The 
air-expansion cylinder is arranged in the same manner as the 
cylinder of a steam engine. It has a slide valve or valve gear, 
which cuts off the air supply at the proper point and permits 
expansion to occur. This expansion should be complete (re- 




FIG. 9. Closed and Open Air Refrigerating Machines. 

duced to back pressure at the end of expansion). This is 
accomplished by having the cut off occur at the proper point. 
As this air expands, doing work at the expense of its intrinsic 
energy, its temperature is decreased so that when the exhaust 
pressure is reached the air may be at some temperature between 
-50 F. and -100 F. The temperature is fixed by the 
amount of expansion. This cold air is now discharged into 
a coil D or a room E, and it removes much heat before it is 
brought up to the temperature at which it enters the com- 
pressor cylinder to repeat the cycle. 

The system on the left is known as a closed system, while 



20 



ELEMENTS OF REFRIGERATION 



that on the right in which the air is discharged into the room 
E is known as an open system. 

The air occupying less volume in the air expander than 
it does in the compressor on account of lower temperature, 
means that there will be less work returned by the expander 
than that required by the compressor; hence power must be 
supplied by an external motor of some form. 

This may be a steam engine as at F, Fig. 9, or an electric 
motor may be applied. 

To show the work done by indicator cards the compressor 




FIG. 10. Cards from Air Refrigerating Machines. 

and expander cards are shown in Fig. 10, assuming zero clear- 
ance. This may be assumed, since clearance does not affect 
the work of a card. These cards may be superimposed and 
the area 2356 shows the net work which must be supplied 
if friction be disregarded. This is the work that the motor 
must supply. The real work, of course, if / is the percentage 
friction, is 

, /loo+A /loo A 

Net work=( ^-larea 1234 area 4^67. 

\ 100 / V ICQ / 



METHODS OF REFRIGERATION 21 

In this machine, air, by compression, is put into such a 
condition that the water supply will abstract heat and then, by 
expansion, it is put into such a condition that it will abstract 
heat from a place of low temperature. 

The advantages claimed for these machines are: the use 
of no chemical which might lead to explosions or loss of life 
due to accidental escape of gas; the possibility of very low 
temperatures; simple construction and the accessibility of 
all parts. 

The first air machine was designed by Gorrie in 1849. Kirk 
designed one in 1863. In 1877 the Bell-Coleman improvements 
made the machine practical, and the application of this machine 
to ocean steamships made possible the cold-storage shipments 
of meat. The machine was improved by a number of later 
inventors. 

There are few air machines used to-day, owing to the greater 
efficiency of types of apparatus using other working substances.- 
But efficiency is not always the criterion by wfyich to judge 
of the advisability of using a certain form of machine. Reli- 
ability, ease of operation, small maintenance cost, and absence of 
poisonous substances may be important factors to consider in' 
making a selection. For such reasons air machines are still 
in use. One of the most common forms of air machines used 
in the United States is the Allen Dense Air Machine, shown 
in Fig. ii. -In this the three cylinders, steam, compressor 
and expander, are placed beside each other, and are connected 
to three cranks of a common shaft. The cylinder A in the 
front of the figure is the expansion cylinder, the second is the 
compressor cylinder, and the back cylinder is that of the steam 
engine. Between the compressor and expander is seen the 
plunger of a small air pump used to maintain the air pressure 
in the system and make up for any leaks. This is driven 
by an extension from the cross-head of the compressor. A 
similar extension on the other side of this cross-head drives 
a plunger of the circulating pump which forces water through 
the cooling chamber B placed on top of the machine. Two 
eccentrics on the shaft control the various valves. The pipe 



22 



ELEMENTS OF REFRIGERATION 



C takes the cool compressed air from the coils in the water- 
cooler to the expansion cylinder A, and after expanding, the 




air is passed through pipe D to the refrigerator, and then 
returned to the compressor through E. 



METHODS OF REFRIGERATION 23 

This apparatus is known as a dense air machine. The 



air is at 60 to, 70 Ibs. gauge pressure on the low-pressure side, 




the high pressure ranging from 210 to 240 Ibs. As will be 
seen later, the refrigerating effect is due to the ratio of these ^ 
two pressures and not to the absolute value of each. By ^ l 
using a high pressure on the lower side, the displacement of 



24 ELEMENTS OF REFRIGERATION 

the cylinders for a given amount of refrigeration is materially 
decreased. v 

The diagrammatic arrangement of the machine is shown 
by the maker, H. B. Roelker (Leicester Allen, 1879, inventor) 
in Fig. 12. F is the compressor cylinder, in which a special 
pair of valves, driven by eccentrics G and H through rock 
shafts, give ample outlet area at the proper time. The com- 
pressed air is then passed through the copper coil /, placed 
in the water-cooler B, where it is cooled down almost to the 
temperature of the water entering at / from the pump K. 
The pump is driven from the cross-head of the compressor. 
The water used in the cooler passes through the jacket of the 
compressor before being discharged. The cooled air passes 
through the pipe C to the expander A, which is controlled 
by a riding cut-off valve gear as shown. After expansion the 
cold air leaves by D and passes through an oil and snow trap 
L, entering an ice-making box M, or that part of the system 
in which the lowest temperature is required. The ice box 
may be a steel brine tank containing coils for the passage of 
the air, or it may be a double-walled casting containing cells 
for the ice-making cans. These cells are supplied with brine 
to fill the space between the casting and can, thus conducting 
heat from the can to the air at a higher rate than that at which 
it would otherwise pass through an air space. The hollow 
part of the casting is that through which the air passes. The 
air is next conducted to the refrigerating room, where the 
temperature need not be so low as that required to make ice. 
If a low temperature is desired in a room, some of the low-tem- 
perature air will have to be taken directly to that room. The 
air is distributed through the room in coils of pipe N and then 
is taken to a water butt, where it cools drinking water to 40 
F. or 50 F. The air is then returned to the compressor through 
the pipe E. If the air is still at a low temperature, it is some- 
times passed around the pipe C, and this cools the air going 
to the expander so much that a very low temperature is ob- 
tained. The pump O is the air-charging pump driven from 
the cross-head of the compressor. This pump draws air through 



METHODS OF REFRIGERATION 25 

its plunger, and after compression the air is delivered to the 
trap P, which is surrounded by cold water. This cools the air 
and causes a large part of the moisture brought in from the 
atmosphere to be separated and drained off. This air is then 
delivered to the pipe E and is. mixed with the air going to 
the compressor. The valves Q and R cut off the low-temper- 
ature parts when it is desired to operate the by-pass S. The 
valve T allows hot air to enter the expander from the com- 
pressor and thus pass into the trap L, removing grease and snow 
from it. The trap or separator!, has a double bottom or steam 
jacket which may be used to melt any congealed oil or water, 
and so open up the line if closed. 

To start this machine, the blow-valve on the expander 
and petcocks on the traps are kept open until no more grease 
passes through. Then the valves Q and R are opened and S 
closed. After this T is closed. The circulating water is then 
turned on, and gradually the low-pressure side should be 
charged by until a pressure of 60 Ibs. is reached. The high- 
pressure will then be 210 Ibs. The petcock on the water trap 
P should be opened to keep the water level below the half-full 
point. The stuffing-boxes, which contain three or four metallic 
rings, an oiling ring and three or four rings of soft packing, 
should be supplied with oil. This oil keeps the packing tight 
with little tightening of the gland, and consequently little 
friction. These stuffing-boxes are placed at places where the 
greatest loss of air occurs. The sight-feed lubricators are con- 
nected to the stuffing-boxes. The air pistons are packed with 
cup leathers which last about two months for steady work. 
They are made of ^ in. thickness and are kept flexible 
by soaking in castor oil. Once or twice a day the machine 
is cleaned of oil and grease by opening S and closing Q and 
R, and then opening T, T' and T" . After this, steam is passed 
into the jacket of L and the petcock is opened. A blow-off 
from the expander is also opened. This is done for about 
one-half hour. A change in the ratio of the two pressures is 
due to leaky pistons, while a drop in the low pressure is due to 
leaky stuffing-boxes. These machines are made in small sizes; 



26 



ELEMENTS OF REFRIGERATION 



the largest are of 3 to 4 tons capacity. They are used chiefly 
for marine work. There are a number of foreign air refriger- 
ating machines. Such firms as Haslam & Ccx., J. & E. Hall, 
and I. & W. Cole are engaged in making these. They vary 
only in "theTHatfer of details from the machine just outlined, 
and for that reason these will not be described. 
/ The system of refrigeration using a volatile liquid is shown 
in Fig. 13. To be a little more definite, assume that anhydrous 
ammonia is used as the working substance. The compressor 
A relieves the pressure in the coil B by drawing vapor from 




FIG. 13. Compression Refrigerating Machine. 

the coil, since the coil is connected to the suction side of the 
compressor. The vapor thus removed is compressed by A 
and delivered under pressure into a condenser coil C. The 
vapor will be compressed in C until the pressure is such that 
the temperature of saturated ammonia vapor at that pressure 
is slightly higher (about 10 to 20) than that of the water 
coming from the supply D. When this pressure is reached, 
the water, having a lower temperature than that of saturation 
of the ammonia, will abstract heat from the ammonia and cause 
it to condense so that liquid ammonia will flow into the receiver 
E. If now the pressure in the coil B is such that the tempera- 



METHODS OF REFRIGERATION 27 

ture of boiling for ammonia at that pressure is above the 
temperature of the substance around the coil B, the ammonia 
gas and liquid in the coil will give up heat to the substance 
through the coil and will be cooled off, but nothing further 
can happen. If, however, the boiling temperature corresponding 
to the pressure is less than that of the substances around the 
coil B, then heat will flow from them into the ammonia in the 
coil and cause the liquid to evaporate, requiring the further 
action of the compressor to keep the pressure low enough to 
remove heat from the substances near the pipe. Of course, if the 
first condition were true, no vapor would form and the action 
of the compressor would reduce the pressure so that the boiling 
temperature would at least be low enough to remove heat from 
the substances. The supply of liquid ammonia is regulated 
by the valve F, known as anjexgansion valve. It is in reality 
a throttle valve, throttling the liquid ammonia from the high 
pressure in C to the low pressure in B. The coil B may be 
placed in a room to be refrigerated or it may be placed in a 
tank G, containing brine of a low freezing-point. This brine 
is cooled and sent out to rooms which are to be refrigerated, 
or to ice tanks, and after receiving the heat, the warm brine 
is returned to the tank to be cooled again. The first system; 
is known as the direct-expansion system, while the latter is 
called the brine system of refrigeration. 

The various types of compressors used will be described 
in a later chapter. At this point, however, one form of com- 
pressor will be shown in Fig. 14. This is a steam-driven com- 
pressor of the Frick Co. 

A Corliss steam cylinder A drives a shaft B with two 
cranks. To the steam-engine crank is connected the rod of 
one ammonia compressor, while on the other crank at 180 
is attached the connecting rod of the other compressor. Thus 
one steam piston operates two ammonia pistons. In some 
cases the crank to which the two connecting rods are attached 
is of the center type; three bearings are then used. This 
compressor is single-acting. Low-pressure ammonia enters at 
C and passes into the cylinder on the up-stroke of the piston 



28 



ELEMENTS OF REFRIGERATION 



D. The long stuffing-box E is quite a common feature of all 
compressors, as is the long piston with a number of piston 
rings. These are necessary to prevent the escape of ammonia, 




which is poisonous and expensive. On the down-stroke of the 
piston, the large suction valve in the center of the piston is opened 
by the vacuum produced on the upper side of the piston, and 
vapor is drawn over to that side. On the return stroke of 
the piston, the vapor is compressed in the cylinder until the 



METHODS OF REFRIGERATION 29 

pressure is slightly above that in the discharge space E, when 
it opens the valve F at the center of the head of the cylinder. 
This valve is forced down by a small spring so that there is only 
a slight increase in pressure above the line pressure before 
the valve opens. The vapor pressure in the discharge holds 
it to its seat on the down-stroke of the piston. The cylinder 
head G is not bo'lted fast to the cylinder barrel. It is held 
down by the springs H which press against the main head /, 
attached to the barrel. The purpose of the safety compressor 
head is to avoid the danger of blowing off a head if anything 
should lodge on top of the piston. If the suction or discharge 
valve should break, or if scale should accumulate and, lie on top 
of the piston, the small clearance which exists in this com- 
pressor would not be large enough to care for this material, 
and with a rigid head the cylinder would break. With the 
safety head the springs would yield and permit the head to 
lift. If for any reason liquid ammonia were to collect and 
the discharge valve would not relieve it, then the head would 
rise. Around the cylinder is a water jacket / for the removal 
of some of the heat of compression. The value of the jacket 
is questioned by some. If too much water is not used, the 
heat removed will not have to be taken out in the condenser, 
and so nothing is lost. Moreover, any heat removed during 
compression decreases the work, so that there is some saving 
by the judicious use of the jacket. If much water is used, 
there will be a loss due to the cost of water being greater than 
the saving due to the jacket. K is an indicator valve and 
L is a purge valve used to manipulate the compressor. 

The layout of a plant using the De La Vergne apparatus 
is shown in Fig. 15. In this the vapor, or, as it is usually called, 
the gas, enters from the refrigerating rooms or brine tank, 
and passes to the suction side of the compressor. This line 
is connected to the gauge board, where a suction gauge is in- 
stalled. This gauge is, of course, controlled by a valve to 
permit of its removal and repair. The suction is sometimes 
connected to the liquid line by an equalizing pipe for manip- 
ulation of the plant. The compressed gas then passes over 



30 



ELEMENTS OF REFRIGERATION 




METHODS OF REFRIGERATION 3l 

to the condenser. This is a coil of pipe made of return bends. 
The hot gas enters at the bottom and as it passes upward it 
is condensed, special bends being used to remove the liquid 
at different places. These various drip lines are connected, 
and finally the liquid is delivered to the storage tank B, from 
which it discharges through the expansion valve C into the 
expansion coil D. The various euqalizing pipes serve to equalize 
pressures at various points of the system, so that syphonic 
action may not be set up. The liquid after entering the re- 
frigerator is changed into vapor and returned to the compressor. 
The passage through the scale separator E removes the danger 
of scoring the cylinders. The valves^at the top of the'oil sep- 
arator A and condenser are to rid the system of non-condensible 
gases which collect there. These gases are due to air which 
may be drawn in, or from the oil which may be decomposed. 
In some cases ammonia may be decomposed. The cooling water 
is discharged from the pipe F. 

There are other substances used in compression systems. 
^Sulphur dioxide, carbon dioxide, and methyl chloride are the 
common ones spoken of to-day. Various ethers and alcohols 
have been used and certain mixtures of liquids, such as C02 
and 862, have been tried. On account of cost, danger from 
use, pressures demanded, and sizes of parts, some prefer one 
substance and some another. The theory underlying all of 
these is the same, and the description given above would apply 
to any of them. In all machines the ammonia is raised by 
compression to such a pressure that the water supply can 
remove heat from the ammonia and condense it, and by use 
of the throttle valve it is reduced to such a pressure that it 
will remove heat from a place of low temperature. 

The absorption machine depends for its action on the 
fact that for every concentration of aqua ammonia, or for 
every per cent of a solution of ammonia and water, which is 
anhydrous ammonia, there exists a certain temperature at 
which the solution will boil under a given pressure. Thus, 
if 35% by weight of a solution of aqua ammonia is NHa, this 
will boil at 227 F. under a pressure of 170 Ibs. gauge, and the 



32 



ELEMENTS OF REFRIGERATION 



same solution will boil at 110 F. if under 15 Ibs. pressure. 
Now ammonia under 170 Ibs. pressure would boil at 91 F., 
and at 15 Ibs. gauge pressure it would boil at o F. If water 
were available at 80 F. and steam at 235 F. or 10 Ibs. gauge, 
the following might be done: 

If the aqua ammonia or liquor of 35% concentration in the 
generator A be heated by the steam at 235 F. in the steam 
coil B, the solution will boil and the ammonia and water vapor 
will produce a gauge pressure of 170 Ibs., and this is sufficient 
to have the ammonia condense in the condenser C if water 
at 80 F. is passed over the pipes. If the ammonia collected 




FIG. 1 6. Elementary Absorption Machine. 

in the receiver D is passed through the throttle valve E into 
the coil F, where it may abstract heat from brdne, it will boil 
at o F., if the pressure is maintained at 15 Ibs. If an aqua 
ammonia solution in the tank G, called an absorber, is not 
allowed to get above 1 10 F. by the cool water coil H, and is 
not allowed to get stronger than 35% concentration, it will 
absorb ammonia and keep the pressure in the absorber and 
the line leading to F at or below 15 Ibs. gauge. To keep the 
solution in the absorber in condition to absorb ammonia, the 
weak liquor in the generator, from which the ammonia was 
removed, is allowed to flow into the absorber, the pump 7 
forcing the strong liquor from (7 to A. 



METHODS OF REFRIGERATION 33 

This is the explanation of the simple absorption machine, 
but there are several refinements which are used. Certain 
phenomena will have to be described. When an aqua solution 
boils, not only ammonia escapes, but also water vapor. More- 
over, the heat supplied will have to be not only that required 
to drive off the ammonia (heat of solution) and that required 
to evaporate the moisture, but also enough to superheat the 
ammonia vapor and water vapor, since these leave the gen- 
erator in a superheated condition. This excess of superheat 
must be removed and to reduce the amount of heat to be taken 
out by cooling water, and to reduce the heat supply to the 
generator, the cool strong solution coming from the absorber 
is caused to flow over trays through which the heated gases 
pass from the generator A . In this way the liquor is heated 
and economy effected. This apparatus is known as the an- 
alyzer, K. 

The water vapor condensing in the condenser would absorb 
some ammonia and reduce the efficiency of the apparatus. 
To reduce this loss it is customary to pass the vapors leaving 
the analyzer through tubes L over which the cool, weak solu- 
tion from the absorber, or water from the condenser, flows. 
In this way the temperature of the mixture of ammonia and 
water vapor is so reduced that most of the water vapor is 
condensed and separated by the separator M , and sent back 
to the analyzer. L is known as a rectifier or dehydrator. 
Of course, this water absorbs ammonia and reduces the amount 
sent to the condenser, but it is not delivered to the condenser 
and so causes no trouble. The last change which is introduced 
ior economy is to pass the warm, weak solution, which is to 
go to the cooled absorber, around pipes carrying from the 
absorber the cool, strong liquor, which has to be heated. This 
interchange saves much heat. The apparatus is known as 
the interchanger, /. 

Before passing to the actual arrangement, one other point 
must be mentioned. The solution is changed from one con- 
centration to another in the absorber and in the generator, and 
it must be remembered that it is the weak concentration which 



34 



ELEMENTS OF REFRIGERATION 



fixes conditions in the generator and the strong concentration, 
those in the absorber. 

The heat of solution when aqua ammonia changes from 
one concentration to another must be cared for by the cooling 
coil in the absorber, so that there is no increase in tempera- 
ture, which would cut down the possible concentration. The 
computations for this system will be given in the next chapter. 

Fig. 17 shows the absorption machine diagrammatically. 
In this arrangement the strong solution in A is boiled by the 
steam in B. The vapor passes through the analyzer K, where 




FIG. 17. Complete Diagram of the Absorption Machine. 

it meets the down current of warmed strong liquor coming 
from the exchanger /. This cools the vapor and warms the 
liquor, and, it may be, drives off some ammonia. The vapor 
then passes to the rectifier or dehydrator, L, which is cooled 
by the strong h'quor pumped by pump 7 from the absorber. 
This solution is cool enough to condense most of the moisture 
in the vapors. The water formed absorbs ammonia, and this 
liquor is removed by the separator M, and is passed back 
to the analyzer. The liquid from the condenser C passes to 
the receiver D and through the valve E to the expansion coil 
F, in the brine tank. From the absorber G with its cooling 
coil H the liquor is pumped by / to L and then to the inter- 



METHODS OF REFRIGERATION 



35 




ELEMENTS OF REFRIGERATION 




METHODS OF REFRIGERATION 37 

changer or exchanger /, after which it enters the analyzer. 
The weak liquor from A passes through the exchanger J to the 
absorber G. 

Fig. 1 8 illustrates the construction of an actual absorption 
machine made by the York Manufacturing Company. The 
condenser, absorber, and expansion coils are all of the exposed- 
coil type. The water lines going to condenser, dehydrator, 
and absorber are not shown. Purging valves are shown at 
various high points. They are connected by purge lines which 
are not shown. For purging this system the best location is at 
the absorber, for here all of the ammonia is absorbed, and the 
gas remaining is true non-active gas. The various parts of 
the apparatus, especially the expansion coils, should be purged 
into the absorber, so that any ammonia coming over may be 
condensed. 

Fig. 19 shows the equipment of an absorption plant as 
made by the Carbondale Machine Co. This differs from that 
of Fig. 18 in that a double-pipe condenser is used, instead of 
an atmospheric one; the absorber is a tubular absorber; the 
weak liquor is cooled before entering the absorber and the 
expansion coil is in a brine cooler. The action of the apparatus 
can be followed from the description above. 

The evaporation of a portion of a body of water, so as to 
freeze the remaining portion, has been used in a natural way 
for centuries. One of the first successful machines acting on 
this principle was made by Edmund Carre about the middle 
of the last century. The apparatus consisted of an air pump 
attached to a cylindrical vessel containing sulphuric acid. 
A carafe containing water was attached to the vessel by a hose 
and then the air pump was started. As the pressure was re- 
duced, the water in the carafe would boil, due to its own heat, 
and the sulphuric acid would absorb the water vapor, lower- 
ing the pressure still further. The heat of vaporization of 
the vaporized water would be taken from the water in the 
carafe until finally this removal of heat would cause the re- 
maining water to be frozen. 

This invention has been followed by a number of patents, 



51162 



38 ELEMENTS OF REFRIGERATION 

and. some actual installations. John Patten has invented 
apparatus for ice manufacture on a commercial scale, but the 
value of such installations has not been proven. A. J. Stahl 
has used a Patten plant at South Bend, Indiana, for the pro- 
duction of 30 tons a day. The drawback is to obtain the high 
vacuum necessary for freezing. Water boils at 32 F. when 
the pressure is less than 0.08 lb., or 0.16 in. of mercury. A 
still lower pressure is required to freeze ice in a short time. 
That such ice is pure is assumed, because the expansion of 
the gases within living organisms at this low pressure causes 
the organism to rupture. Under very low pressures the evap- 
oration is so rapid that the ice forms immediately. 

In one type of machine, patented by J. H. J. Haines in 
1901, an air pump was attached to a vessel containing water 
to be frozen, to the space outside this vessel and within an iron 
receptacle, and to a vessel containing sulphuric acid. As the 
air pump was operated, the whole system was exhausted. The 
space outside the water vessel being exhausted, prevented 
heat from passing across and so, when the pressure was low 
enough for the water to boil by its own heat, this heat could 
come only from the water, since the vessel was well insulated 
from the outside by the vacuum space. This abstraction of 
heat caused the remaining water to freeze. The acid in the 
third vessel absorbed the water vapor formed and thus reduced 
the pressure. 

In the apparatus patented by W. T. Hoofnagle in 1903, 
water to be made into ice passes through a vessel A , Fig. 20, 
which may be used to clear the water or filter it. It enters 
the chamber B, in which it is sprayed over a series of trays; 
the fan at the bottom keeps up a circulation. The chamber 
is connected to the intermediate cylinder D of a three-stage 
compressor or air pump. This reduces the pressure in B to 
such an extent that the water is de-aerated, and a small amount 
v of evaporation cools the water. This is admitted from the 
pipe E into a chamber F by two valves. The chamber F is 
connected to the low-pressure cylinder G of the three-stage 
vacuum pump or compressor. The air and water vapor drawn 



METHODS OF REFRIGERATION 



39 



out by.G is sent to D and after compression it is finally delivered 
by H. In the chamber F are two trays which are oscillated 
by rods operated by cams. When in the position shown, 
water is discharged from the nozzles on these trays, and as 
it flows along the tray the evaporation of water under the 
very low pressure causes the remaining water to freeze, making 
a cake of ice. 

It is considered advisable in all these machines to spread 
the water in a thin layer so that freezing may take place readily, 




FIG. 20. Hoofnagle Vacuum System of Ice Making. 

as evaporation can occur over a large surface. Patten sprays 
his water from a movable head. 

Another machine for which claims are made is that due to 
Le Blanc. In this the vacuum is obtained by steam aspirators 
in series, each compressing the air exhausted by the previous 
one. By using the Le Blanc condenser pump, this apparatus 
is used to advantage. In this country the development of this 
machine is being made by the Westinghouse-Le Blanc interests. 
This apparatus is being developed for use on ships of the French 
navy, on some of which serious accidents occurred by the 



'40 ELEMENTS OF REFRIGERATION 

bursting of the parts of other forms of refrigerating apparatus. 
The description of these machines is found in Ice and Refrig- 
eration, for July, 1912, and Aug., 1910, and Power, Jan. u, 1916. 
The chemical process refers to the cooling of water by the 
addition of some soluble chemical. If ammonium nitrate is 
added to water, the temperature of the solution is much lower 
than that of the water, a temperature decrease of 40 being 
obtainable in this way. If the vessel containing the solution 
surrounds some object, heat will be abstracted and even ice 
may be formed. If calcium chloride is dissolved in water, a 
reduction of 30 can be obtained in the temperature of the 
water. After this the salt may be recovered by evaporation 
and used again. This principle has been used for actual appa- 
ratus to produce low temperatures. 



CHAPTER III 
THERMODYNAMICS OF REFRIGERATING APPARATUS 

WHEN ice is made it is difficult to tell at just what tem- 
perature some of the ice forms, and also, after forming, it may 
be possible to reduce the temperature of some of the ice. Hence 



11 10 

5. ,6 




FIG. 21. Cards from Air Machine. 

the amount of heat required to form a pound of ice is not 
definite. However, if ice melts, the melting does not begin 
until 32 is reached, and it continues at this temperature until 
all of the ice is melted. For these reasons the amount of 
heat required to melt a pound of ice is used as a unit rather 
than that removed to make a pound of ice. 

Refrigeration is usually measured in tons of ice-melting 
capacity per twenty-four hours. Since the latent heat of 
fusion of ice is 143.4 B.t.u. per pound, according to the latest 

41 



42 ELEMENTS OF REFRIGERATION 

experiments, this unit means the removal of 286,800 B.t.u. 
per twenty-four hours, or 199. 2 -B.t.u. per minute. 

The air refrigerating machine has a compressor and an 
expander, the indicator cards of which are shown in Fig. 21. 
The expansion and compression curves are of the form pv n = 
const., and the compression is from the pressures p\ to p2. 
The cards are shown with no clearance. The area of the 
card is 

Area 3-2-10-1 i+area 10-2-1-9 area 4-1-9-11 
or 

rn . 

I pdvpiVi=a.rea,, . . . . (i) 
Jht 

pv n = const. =piVi n = p2V2 n (2) 

const. v 1 ~ n 



r* rm 

. pdv = const. I v~ n dv 

Jvi Jn 



Hence Area = (^22-/>ii) i -- -J .... (4) 



(p2V2-plVl) ...... (5) 

ft - I 



K/TT%\T* T 1 1 ( ' f\\ 

ni 



since pv = MBT for perfect gases, 

where p = pressure in Ibs. per sq.ft.; 

v = volume in cu.f t. ; 
M = Ibs. of gas; 

B = constant = , 1544 ; 
mol. wt. gas 

T = absolute temperature in deg. F. 



THERMODYNAMICS OF REFRIGERATING APPARATUS 43 

k I 
By the thermodynamic theory B=Jc p . 

Hence 

2 -ri]. ... (7) 



The temperature T\ is fixed by the temperature desired in 
the refrigerator. If the system is open (air discharged from 
expander into cold room), T\ is the temperature of the room, 
while if a closed system is used, T\ must be about 10 below 
the cold room, or the warmest place refrigerated, since 



T2fr" = Tlpi n , (8) 

or 

(9) 



The work of the expansion cylinder is 



-:"". . (10) 



In this TQ is fixed by the cooling water* being about 10 F. 
above the water on the opposite side of the cooler metal at 
the point where the air leaves. 

In most compressors and expanders the action is so rapid 
that the compression is adiabatic and n equals k. This gives 



p=/c p (r 2 -r 1 ), . . . . (n) 

Workexp =Jc P (T 6 -T 7 ). . . .7. . (12) 

If there is friction of 100 / per cent, the net work required 
to drive the machine is 

Net work =MJc p [(i+f)(T 2 -T 1 )-(i-f)(T Q -T 7 )]. (13) 



44 ELEMENTS OF REFRIGERATION 

With no friction the work is 

Net work = MJc p [(T 2 -T 1 }-(T Q -T 7 )], . 



(14) 



The expander cylinder should always be carefully lagged 
to prevent the entrance of heat, but in the compressor the use 
of the water jacket reduces the compression line by abstracting 



heat and thus saving work. If it is assumed that the exponent 





FIG. 22. Card with Clearance. 



w = i.35 in the compressor, while = 1.4, the expression for 
net work with friction becomes 

Net work 



-r 7 (16) 

(17) 
(18) 



(19) 



The effect of clearance is seen from Fig. 22, in which the 
compression 1-2 is followed by the discharge 2-2', and then 



THERMODYNAMICS OF REFRIGERATING APPARATUS 45 

the air 2^, which is retained in the clearance space, expands 
frorri 2' to i'. The net work is 1-2-2'-!', and the net amount 
of air drawn in is I'-L The temperature at 2' is thatjit^2, 
hence that at i' is the same as at i . 



1 JT "- 1 A IV T i T* T* \ 1 ,*/ /v A fg> T fmi rr^l 

= Mi Jc p (T 2 -Ti)-M i Jc P (T 2 -Ti 




(21) 



where M=M\M f i, or the weight taken in from i to if. 

This expression is the same as that in Eq. (7) without 
clearance. There is no effect of clearance on the work of a 
compressor for which the expansion and compression lines are 
complete, and have the same exponent. This may be said 
of an expander also, when the cutoff is such that the expansion 
is complete or just reaches the back pressure at the end of the 
stroke, and the point of compression is such that the compres- 
sion is just carried to the initial pressure. 

The above is true as far as indicated work is concerned, 
but the work required to drive the compressor is slightly greater 
with clearance, as displacement must be increased for a given 
discharge if clearance is present, and there is consequently 
more friction. Let the clearance 2' 3 be / times the dis- 
placement Vi V f 2 or D. 

That is, let 



The volume of air taken in is V\ V'\, or 



46 ELEMENTS OF REFRIGERATION 

The expression within the bracket is known as the clear- 
ance factor. 

V MET i 



For the expander with complete expansion and compression 



The refrigeration is produced by adding heat to the air, 
increasing the temperature from TI to the original Ti, at 
constant pressure. Hence 

Refrigeration = JlfCp(ri TV) = 199.2 Xtons of ref.; . . . (25) 
M = weight of air required per minute; 
c p = specific heat at constant pressure = 0.24 for air. 

The heat removed in the cooler is given by 

T 6 }=G(q' oM -q' la ). . . (26) 



M = weight of air per minute; 
G = weight of cooling water per minute; 

liquid of cooling water at outlet temperature; 
of liquid of cooling water at inlet temperature. 



-r, , Refrigeration . , 

The expression, in B.t.u. s, - ^ - - is known as the 

Work 

refrigerating effect. With no friction this becomes 



Now 

T 2 - 
T 2 



THERMODYNAMICS OF REFRIGERATING APPARATUS 47 
since 

Ti. Ti \pv 

.'. Ref. eff. = -^ =-^ . 

1 2 1 2 -tl 

This shows that as T 2 Ti becomes smaller the refrigerating 
effect or the refrigeration per unit of work increases. 
The general expression is 

rrt rrt 

Ref ' eff - == [(i.io)(r 2 -r 1 )(i+/)-(r 6 -r 7 )(i-/)] > ' (28) 

If a problem is given the following steps are taken: (a) 
TI is fixed by the temperature of the room or place to be cooled 
and TQ by the temperature of the cooling water. Of course 
the coldest water should be brought in contact with the coldest 
air, or the air and water must flow in opposite directions along 
the cooling surface, giving a counter-current flow, (b) By 
(18) and (19) the temperatures T 2 and T^ are found after 

assuming the ratio . It will be noted that T 2 and Tj depend 
Pi 

upon the ratio , and not upon the actual values of the pres- 
sures, (c) By (25) M, the weight of air per minute, is found 
for a given number of tons of refrigeration, (d) G, the amount 
of cooling water per minute, is found by (26). (e) The dis- 
placement of the compressor per minute is found by (23). 
(/) The displacement of the expander per minute is given by 
(24) and the horse-power is given by dividing (17) by 33,000. 
H.P. to drive machine = 



(29) 



33,000 



There are some change^ to be noticed before proceeding 
with a problem. If in the expander the cutoff is too late 

\ 



48 ELEMENTS OF REFRIGERATION 

the areas 7-10-9 and 11-12-13 will be lost, decreasing the 
work done by the expander and increasing the net work done 
by motor which drives the machine. Moreover, TV is now 
higher than it was when the air was expanded down to the 
lowest pressure. This gives less refrigeration, since the free 
expansion 7 to 9 is throttling action ad will not cool the air. 
The temperature at 13 is higher than the temperature TQ 
of the incoming air, because T'i is higher than TV would have 
been if the expansion were complete. This even makes TQ 




FIG. 23. Incomplete Expansion and Compression in Expander. 

higher than it should have been, increasing TV and still further 
cutting down the refrigeration 

Mc 9 (Ti-T 7 ). 

This incomplete action makes the displacement Vg V\% 
less than it would be with complete expansion and compres- 
sion, FIO Fi 3 . This is the only advantage. 

Since one would be foolish to design an expander with 
incomplete expansion and compression, this will not be further 
investigated although by calculations the various temperatures 
may be found for any conditions. 

Note. The following discussion gives the temperatures, assuming no 
compression, with expansion such that fr-=ip\. 

Air entering at temperature T 6 must compress the clearance air ID, 
at temperature Tr, from pi to pi. 



The energy in the air contained in the cylinder is 



pJD 
k-i 



THERMODYNAMICS OF REFRIGERATING APPARATUS 49 

The air brought in from the storage tank to bring this up to the pres- 
sure p 2 is m Ibs., and the energy entering from the tank at constant pressure 

is mc p T 6 . The energy after mixing is -^ . 



Hence 



JcpTt 

Now the weight of air in the clearance space is 

m '=^T (3i) 

DL T 

The temperature of the mixture in the clearance space, after the air 
enters to fill the space, is given by 

p 2 lD p 2 lD p 2 



(m+m'}B \ ID (p 2 -p l )B p l 



Jc p T< 



When the remaining air (Mm) passes into the cylinder, the following 
equation is true: 



- - 

K I 

....... (33) 

(M-m)T t +(m+m')T v . 

T "=- -^^n> -- ...... (34) 

In this TV is higher than T 6 and T 6 is higher than T 6 . If now the air 
at volume Vy expands from pressure pz to a pressure 2p\, the temperature 
of discharge will be 



50 ELEMENTS OF REFRIGERATION 

This will be the temperature of discharge, since the free epxansion 
is a throttling action of constant temperature. Even if T<> were equal 
, n-i 

to T t , Ti would be higher than it should be by the factor 2 n . This 
means that the refrigeration is decreased. 

The work returned by the expander in this case is 

BT '-(p,- Pl)I D. . (35) 



These quantities may all be computed. 

The compressors, as usually constructed and used, operate in such a 
manner that complete expansion and compression result, and conse- 
quently there is no effect, due to clearance space, on the temperature 
or work of that part of the apparatus. 

The effect of moisture in the air is to reduce the refrigerating 
effect and increase the net work. Of course, this moisture 
effect is not felt if the same air is used over and over 
again, since the first chilling dries the air and removes the 
moisture. 

Air contains a certain amount of moisture. The amount 
is told by a hygrometer. One form of this apparatus consists 
of two thermometers, one of which has a wet wicking around 
it. If now, these two thermometers are whirled in the air, 
it will be found, usually, that the wet-bulb thermometer will 
read less/ than the dry one. The amount by which the wet 
bulb is lowered depends on the moisture present in the air. 
If the air is saturated with moisture, there will be no difference, 
while if the air is dry, there is a large difference in the tem- 
peratures recorded by each. The amount of moisture is desig- 
nated by relative humidity. Relative humidity is the ratio 
of the amount of moisture, m a , in a cubic foot of air compared 
with the amount of moisture, m s , to saturate it, or 



p = relative humidity; 
m a = amount of vapor in i cu.ft. ; 
m t = amount of vapor to saturate i cu.ft. 



THERMODYNAMICS OF REFRIGERATING APPARATUS 51 

If the vapor pressure (vapor tension or steam pressure) at 
a given temperature is p s , the actual pressure, p a , exerted by 
the vapor of relative humidity p is 

pa = Pp- 

Now, if the wet bulb reads t 9 and the dry bulb h, and the 
barometer reading is given by Bar, then according to Carrier 

fr_Bar-fr fc-l , 

P* P* 2755-I.28A/ 

where p = relative humidity ; 

p w = steam pressure corresponding to t w ; 
pa = steam pressure corresponding to /; 
Bar = barometer reading; 
ta = dry-bulb reading; 
/, = wet-bulb reading. 

If the air of relative humidity p and temperature T\ enters 
the compressor, the moisture and air during compression will 
act as a single gas and the temperature T% will be found as 
before. 



The work of compression will be 

7[M^+mc' p ][r 2 -r 1 ], (39) 

M= (pl-pp) 1 ? ( 40 ) 

BL i 

or 



m t = weight of i cu.ft. of saturated steam at temperature T\; 
pi = saturation pressure of steam at temperature T\ ; 



52 ELEMENTS OF REFRIGERATION 

When this air is cooled to temperature T 2 , an investigation 
must be made to see if any of the moisture is condensed. If 
none is condensed the mixture acts as a gas and 



If now VQm S Q>m no moisture is condensed and 

(42) 



for low pressures, and then m m s sVs = amount 
condensed in the cooler. 

In the first case m Ibs. enter the expander and in the second 
case m^Vs enters the expander. 

This moisture is condensed and frozen as soon as it enters 
the expander. It then gives up the heat 
-I ^ \ 

m( q ' & +rf+i 4 4)=c,* U . . . . (43) 
to the cylinder walls and leaves the volume of the air 

'/.,. -...,.... (44) 

2 

The heat c c taken up by the cylinder walls may be assumed 
to be gradually restored during expansion. If this is divided 
between the temperatures T& and T 7 , it might be assumed 
that the amount returned from the walls per dt degrees is 



1 6 Ll 

where a is the value of the fraction. 

Hence the equation for work at the expense of internal 
energy and the heat returned is 

Jmc t dt+JMcdt+madt=-pdV, . . . (45) 



THERMODYNAMICS OF REFRIGERATING APPARATUS 53 

J[mc i +Mc,+ma] = M 

T 6 . V 7 , ,. 

** (46) 



+logege (47) 

From this T 7 may be found. 
The work done is 

W^ = p2 V & +C'pdv -piV 7 

=MBT 6 +J(mc i +Mc v +ma)(T 6 -T 7 )-MBT 7 

=J[mc i +M(c+AB') +ma][T 6 - T 7 ] 

= J[mc t +Mc p +ma][T 6 -T 7 ] ....... (48) 

The net work is 
Work n = J [[Mc v + mc' p ][T 2 - 



-rT][i-/i. . (49) 

The refrigeration is 

JMcATi-T,] ....... (50) 

The refrigerating effect is 



Work n 



, . 



From the expression for refrigeration it is noted that only 
air is considered to be delivered back to the compressor, and 
consequently unless this air received moisture from the space 
through which it was passed, this problem is of little value. 

If a large quantity of water is injected into the cylinder 
during compression to reduce the amount of work by cooling, 
of course the above discussion of the expander would be im- 



64 ELEMENTS OF REFRIGERATION 

portant, and of course some means would have to be used to 
remove the ice formed constantly in the cylinder. 

If the water injected into the cylinder at each stroke is 
m pounds, the following equations should hold for the com- 
pression stroke. 



-pdV, . (52) 
J[Mc4t+mdq'+mpdx+mxdp] = -pdV- (P-p}dV, 



^ dq' = dt, approximately; $~ 

dV = m[(v"-v'}dx+xd(v")]. 
/. Jmpdx+pdV=Jm[p+Ap(v"-v')]dx+mpxdv" 

= Jm(rdx+Apxdv") ........ (53) 

Now 

dp = dr-Apdv"-A(i)"-D f }dp y 

xdp=xdr-Apxdv"-Ax(v"-v'}dp. . . . (54) 
But 



lp = jdt (55) 

Hence 

')" = xdr-^ (56) 



xdr 

- = ~T ' 



[Mc,+m] loge ^+m\ ^- 2 -^- 1 1 =AMB log e ^. . (57') 



THERMODYNAMICS OF REFRIGERATING APPARATUS 55 
MBT 2 f N 

^2=5 - -, ...... (59) 



(60) 
(61) 



[Mc,+m] log e +-L - =AMB leg, . . (57") 

1 1 1>1 ./ 2 Vl L 1 K2 

Equations (59) and (57") will give V 2 and TV They are 
to be solved by trial. p 2 and r 2 are fixed by T 2 . The work 
done in the compressor is given by 

W c = Mc P (T 2 -T 1 )+m(q 2 +x 2 r 2 -q l -x l r 1 }, 

= Mc p (T 2 -Ti}+m(i 2 -ii) ....... (62) 

The remainder of the problem is worked out in the same 
way as in the previous case. 

To apply these formulae, it is desired to cool a room to o 
with cooling water at 60 F., and the data for i ton of refriger- 
ation is to be found. With a 10 rise in the water, a 10 
difference between air and cooler and a counter-current air- 
cooler, the temperature of the air will be reduced to 70 F. 
The air in the refrigerator will be 10 F. Hence 

Ti = - 10+459.6 = 449.6, * ft / 
T Q = 70+459-6 = 529-6. ' 

Suppose this to be an open system and pi is 14.7 Ibs. per 
square inch absolute, and pz is 44.1 Ibs. per square inch gauge. 

-Q o\ 1.35-1 

-o5^ 449 . 6 = 449 .6Xi.432=645 = i85 F, - 



56 ELEMENTS OF REFRIGERATION 

The refrigeration per pound is given by 

356] = 22.6 B.t.u. 



The weight of air per minute per ton = l^Q^ _ g g ^ s 

22.6 

Cooling per minute per ton = 8.83 X .24(645 530) = 244. B.t.u- 
Amount of water per minute per ton = = 24.4 Ibs. 



The work with 15% friction is given by f>, 

Vi< 

Net work per minute per ton 

= 8.83Xo.2 4 [i.ioXi. 15(645-450) -o.85X(530-356)] 

= 209.5 B.t.u. 

Horse-power per ton of refrigeration = : 



42.42 

Clearance factor in compressor with 2% clearance 

i 
= i +0.02 0.02 X (4) 1 - 35 =0.964. 

Clearance factor in expander with 2% clearance 

j_ 
== i +0.02 0.02 X (4) 1 - 4 = 0.966. 



Displacement per minute per ton for compressor 



I4.7Xl44XO.964 

Displacement per minute per ton for expander 



= I 



14.7X144X0.966 
Refrigerating effect 

= 450-356 = 94 

i. loX 1 15 X (645 -450) -0.85(530-356) 99 



THERMODYNAMICS OF REFRIGERATING APPARATUS 57 



DENSE AIR MACHINE 

In the dense air machine, or closed system, the initial gauge 
pressure is taken as 44.1 Ibs. per square inch and the pressure 

p2 is 220.5 Ibs. per square inch gauge. The ratio is then 

pi 

2 2 C 2 

' or 4. Hence, if computations are made as above there 

50.0 

will be no change in any results until the displacement is reached, 
when it will be found that these quantities are reduced to 
} of their previous values, giving 



Displacement per min. per ton for compress* 
Displacement per min. per ton for expander 



ton for compressor = 2 6.0 cu.ft. 
'--'--- ~-'-- 10.5 cu.ft. 



The low performance of the air machine coupled with the 
large size of the cylinders of open systems has caused this machine 
to give way to the vapor machines. Since air, however, costs 
nothing and will not spoil substances nor poison persons if 
the system leaks, and since machines built for air are reliable, 
these machines are found in use to a certain extent, especially 
on vessels. 

The thermodynamics of vapor machines is best studied 
from a temperature-entropy diagram. This diagram is formed 
by plotting the entropy of the liquid s' against absolute tem- 
perature, getting the curve AB which cuts the zero entropy at 
32 F., since that is the point from which entropy is measured. 
The value of s' has been found by plotting the specific heat 
of liquid c against log e T and finding the area to any point. 



(63) 



For temperatures below 32 F. the value of s' is a negative 
quantity as is the heat of the liquid q r which is given by 

q'= Ccdt (64) 



58 ELEMENTS OF REFRIGERATION 

From this curve AB, known as the liquid line, the entropy 
of vaporization, is laid off, giving the line CD, the saturation 

line. 

If the distance EF is now divided into proportional parts, 
and this is done with lines at other temperatures and corre- 
sponding points are united, the light dotted lines shown in the 
figure are obtained. These are lines of constant quality. On 
these the quality or the amount of vapor in one pound of vapor 
and liquid is constant. For that reason these are also called 
lines of constant vapor weight. It is known that the entropy 
of vaporization for a quality x is 





For this reason the ratio -^^=x. 
Lr 

From the quality x the volume of i Ib. of mixture, v, may 
be found since 

!>=(i-*XW. (65) 

D = vol. of i Ib. of mixture; 
v" = vo\. of i Ib. of saturated vapor; 
' = vol. of i Ib. of liquid. 

Now (i x) is the amount of liquid present in i Ib., since 
x is the weight of the vapor. The volume of i Ib. of liquid is v' 
cu.ft, and the volume of i Ib. of dry vapor is v" cu.ft. In 
general the quantity (i x)v f is so small that it may be 
neglected, giving 

v=xo" (66) 

The quantities v' and v" are found in the tables of the 
properties of vapors, and for any quality x at a given tem- 
perature, the volume may be found. Conversely, if the volume 
be known, the quality at any pressure may be found by 



THERMODYNAMICS OF REFRIGERATING APPARATUS 59 

and from this equation the values of x for the same volume 
at different temperatures may be computed, and on joining 
these points, lines of constant volume, shown dotted in the 
figure, may be drawn. 

One other thermodynamic quantity which is of great value 




FIG. 24. T.S. Diagram for Ammonia with Thermal Lines. 

may be found from the quality x. This is the heat content i, 
which is defined by 

(67) 



u = intrinsic energy of i Ib. of substance; 
p = pressure in pounds per square foot; 
v = volume of i Ib. in cubic feet; 



60 ELEMENTS OF REFRIGERATION 

For a mixture of a liquid and a vapor 

Au = q'+x P ...... . . (68) 

u = intrinsic energy of i Ib. of substance in foot-pounds; 

*& 

(?' = heat of the liquid of i Ib. in B.t.u.; 
p = internal heat of vaporization of i Ib. in B.t.u. 

Hence 

i = q'+xp+(i-x)Apv'+xApv", 

= q'+xp+xAp(v"-v'}+Apv'. 

By definition the heat of vaporization, r y is equal to the 
internal heat of evaporation p plus the external work when 
i Ib. of liquid is changed into vapor. 

r = P +Ap(v"-v f ). 
From this 

i = q+xr+Apv' ....... (69) 

Since Apv r is a very small quantity, it is customary to 
consider the approximation 

....... (70) 



as true. 

Since in most problems the value of one i is subtracted 
from another, the small term which is almost the same in each 
heat content would be canceled out, and for that reason, al- 
though an approximation, the use of Eq. (70) would lead to 
no large errors as it is ordinarily employed. 

Since 

i=q'+xr, 



and for any given value of i at any given temperature the 
quality x may be found and by connecting the points of the 



THERMODYNAMICS OF REFRIGERATING APPARATUS 61 



same i at different temperatures, lines of constant heat content 
may be found. These are shown by dotted lines. 
The above equations may be written for mixtures: 




0.25 0.50 0.75 1.00 1.25 1.50 

Entropy 

FIG. 25. Heat Content-Entropy (I.S.) Diagram. 



xv, 



(66) 
(70) 



For M pounds of substance 

or 



-si), . . (71') 



62 



ELEMENTS OF REFRIGERATION 

= Mxv" or &V 

or Al 



. (66') 
. (70') 




0.60 



0.50 



0.10 0.10 0.20 0.30 

Entropy 

FIG. 26. 7.5. Diagram with Inclined Co-ordinates. 



It should be remembered that in this saturated region the 
pressure is fixed for any temperature, by the characteristic 
equation of the vapor, and when the words " any temperature " 
were used above, the words " any pressure " could have been 
used. 



THERMODYNAMICS OF REFRIGERATING APPARATUS 63 

Since i is an important quantity in most problems relating 
to refrigeration, and since entropy is needed in discussing 
adiabatics, the coordinates i and 5 are often used for a diagram, 
shown in Fig. 25. This is sometimes called a Mollier diagram. 
In it the line of any temperature or pressure is found by com- 
puting the i and s for a given x. If the points of the same 
quality are united, lines of constant quality may be found, while 
points of the same pressure give lines"of constant pressure. 

This diagram as drawn with the axes of coordinates at right 
angles is such that for a given range of temperatures, there 
is much of the figure which is of no value. To correct this 
the angle between the axes is made much smaller than 90 
by some authors and constructors of charts, giving Fig. 26 
for the Mollier chart. 

If a mixture is heated until all of the liquid is evaporated, 
the further addition of heat at constant pressure will increase 
the temperature of the substance above its saturation tem- 
perature, or it will superheat it. The difference between the 
temperature of the substance and its saturation temperature 
is known as the degrees of superheat. 

Deg. superheat = T mp - T aAt . 

Tsap = absolute temperature of the superheated substance; 
Tsat = absolute temperature of saturation corresponding to 

the pressure; 
/sup = T sup 459.6 = Fahrenheit temperature of the substance ; 

/sat = T Blit 459-6- 

If the entropy and heat content are increased, their values 
will be given by 



/*sup r T au 

( Cj4t+Apv'=tf+r+ I 

JTszt jTnt 



c p dL . (70") 



64 



ELEMENTS OF REFRIGERATION 



The specific heat of superheated vapor is given by the 
letter c p . This may be a constant or a variable. In most 
vapors used for refrigeration, the value of C P is considered 
constant for lack of better information. The value of v is 
found from the characteristic equation of the superheated vapor, 
which is usually taken in the form 



p(v-c)=BT+ap a . 



(72) 



FIG. 27. Cards from Vapor Machines. 

Using these equations, Figs. 24, 25, and 26 are carried out 
beyond the saturation line into the superheated region as 
shown. 

The p-v diagram from the vapor machines with an expander 
is shown in Fig. 27, considering no clearance, as compression 
and expansion are complete. The vapor is drawn into the 



THERMODYNAMICS OF REFRIGERATING APPARATUS 65 



490 32"F 



Abs. Zero 




75V 




0.20 



10" F 




0.25 



0.50 0.75 

Entropy 



FIG. 28. r.S. Diagram of Cycle of Refrigerating Machine Using a Volatile 

Fluid. 



66 



ELEMENTS OF REFRIGERATION 



compressor from 4 to i and is compressed from i to 2. This 
compression not only raises the pressure, but also the tem- 
perature at which the liquid will boil or the vapor will con- 
dense. Hence, if sufficiently high, the pressure will have a sat- 
uration temperature above the temperature of a water supply, 
and if passed through condenser tubes with water on the out- 




Entropy 



FIG. 29. 7.5. Diagram of Cycle of Refrigerating Machine Using a Volatile Fluid. 

side, the vapor will condense. The vapor is driven out from 
2 to 3 into the condenser in which heat is removed to condense 
the vapor. The liquid, which occupies a very small volume 
3-5, is admitted to the expander and expands from 5 to 6, 
after which it is allowed to enter the expansion coils, where it 
abstracts heat from the cool material outside of the coils because 
its pressure has been so reduced that the temperature of boiling 
is lower than the low temperature of the substance around 



THERMODYNAMICS OF REFRIGERATING APPARATUS 67 

the coils. The liquid boils and finally occupies the volume 
4-1. The combination of these two cards gives the net card 






Constant Heat Content 





FIG. 30. 7.5. Diagram of Cycle of Refrigerating Machine (Inclined Axes). 

1-2-5-6, in which 1-2 and 5-6 are adiabatic, and 2-5 and 6-1 
are constant-pressure lines. 

This figure may be placed on the temperature-entropy 
diagram, Fig. 28, or on the i-s diagram, Figs. 29 and 30. 

On the line 1-2 the compression carries the vapor into a 



68 ELEMENTS OF REFRIGERATION 

drier region, as drawn x% = i , so that the vapor is always sat- 
urated and some liquid is present. This is known as wet 
compression. If, however, x\ as at i' were unity, the com- 
pression i '-2' would carry the vapor into the superheated 
region. This is known as dry compression. The compression 
from i to 2 would require work shown by the area 1-2-3-4 
on Fig. 27. 

( Work per po\ind = q2+x 2 p2-qi-Xipi+Ap 2 V2-ApiVi 

= q2 +X2P2 +Ax 2 p2v" 2 - [qi +SIPI +Axipiv"i] 

i2-ii ..... (73) 



In the superheated region the work per pound would still be 
j given by 

W r = i 2 -ii, 

W, = M(i 2 -ii), ..... . (73') 

In the same manner the expression for work in the expander 
is 

W. = M(i&-it). ...... (74) 

Now the work required in the expander is so slight that 
this part of the apparatus is omitted, the complication and 
friction being of greater value than the work regained. In 
that case the net work per minute becomes 

W u = M(i2-iiKi+f)- ..... (73") 

This expression for work is shown by the area 1-2-5-4 
on Fig. 28, since, 

Area (6-^-5-2) = q' 2 +x 2 r 2 = i 2 , 
Area (a-4-i-/) area (a-4-h-b) = x\r\-\-q'\=i\. 

(q'l is a negative quantity.) 

Area (6-^-5-2) area (a-^-i-f) +area (a-^.-h-b}=i2ii 
=Area (1-2-5-4). 



THERMODYNAMICS OF REFRIGERATING APPARATUS 69 

On Figs. 29 and 30 there is no area equal to this work, 
but the difference between the coordinate values of i at 2 and 
at i will give (2*i) or the work. 

In these figures the lines 1-2 represent wet compression, 
while i '-2' represent dry compression. 

The pressure is actually reduced from p2 to pi through a 
throttle valve. Throttling action is of constant heat content. 
Hence the line 5-6 must be changed to 5-6', or from a reversi- 
ble adiabatic or constant entropy line to a non-reversible 
adiabatic or constant heat-content line. This makes 



The heat removed from the refrigerator is that to pass 
from 6' to i, and hence this heat is 



.... (75) 
= M(ii-i 5 ) =MXareaO-6'-i-/). 

By this equation the quantity M per minute is found. 

The heat removed from the ammonia in the condenser is 
given by the heat under the line 2-5 or 2 '-5. This is the 
area (c-$-2-f). In any case this is given by 

i ) ) . . . (76) 



G=lbs. of cooling water per minute; 
<?' = heat of the liquid of cooling water at outlet; 
q\ = heat of the liquid of cooling water at inlet. 

These formulae hold for wet or dry compression. The 
points i and 2 are on the same adiabatic, and hence the values 
of i\ and i% are found in the same entropy column. 

At times after the ammonia is condensed the liquid is 
passed through pipes surrounded by cold water and the liquid 
is cooled down the liquid line to 5'. This is known as after cool- 
ing. This increases the amount of cooling, and if the water is 
available this gain will increase the refrigeration, as % is equal 



70 ELEMENTS OF REFRIGERATION 

to {5 or iy, whichever represents the condition of the liquid 
entering the throttle valve. It will be seen that throttling 
action has changed i& to i v , thus losing the refrigeration 



The quantities may all be found on the I-S diagrams as 
coordinates of the points. The lines are of peculiar shape. 
Adiabatics are lines of constant entropy and throttling lines 
are lines of constant heat content. Constant pressure lines 
are straight lines in the saturated region, but curve when the 
superheated region is reached. 

The loss of refrigeration due to the elimination of the expander 
referred to above, and that of the work of the expander are 
considered to be offset by the simplicity of the apparatus. 

The refrigerating effect is given by 



(77) 



The displacement per minute of the compressor is given by 

' (78) 



n = i.2 for wet compression or 1.33 for dry NHs. 

The clearance factor given in the denominator of this 
expression is the same as that in any compressor for the lines 
1-2 and i'-2 r . are similar lines of the form pv n = const. There 
is no reason why the quality at 2 and that at 2' should be 
different, and if they are the same the lines are the same. 

The volumetric efficiency of a compressor is the ratio of 
the free substance actually pumped to the displacement. 



LT = f , + /- 

D L 



vol. Es. - 

pi 

Voorhees has patented a scheme by which certain savings 
may be effected when there is a chance to use two different 



THERMODYNAMICS OF REFRIGERATING APPARATUS 71 

temperatures of cooling. In most cases there are certain sub- 
stances or spaces to be cooled to temperatures not as low as 
those of other parts of the system, and for such he proposes 
to expand part of the ammonia to one pressure, and another 




FIG. 31. Effect of Clearance. 

part to a lower pressure. If, now, the compressor is large 
enough to displace the proper amount of vapor at the lower 
pressure and at the end of the suction stroke a valve is opened 
to a place of higher pressure, the spring suction valve to the 




FIG. 32. Multiple Effect Indicator Cards. 

low-pressure place is closed and vapor rushes in from the place 
of higher pressure and fills the cylinder to that pressure before 
the return stroke is started. Voorhees calls this a multiple 
effect. The indicator card is shown in Fig. 32. The advantage 
of this apparatus is that for the part of the heat abstracted 



72 ELEMENTS OF REFRIGERATION 

at higher temperature, less work has to be done. 1-2 would 
be the line for the low-pressure compression. i'-2 / is the 
combined line. The work done is 4-1-1 '-2'-$. The saving 
has been i'-6-i. Voorhees accomplishes this by allowing the 
piston of the compressor to override a port at the end of the 
stroke, the port leading to the space carrying the high-pressure 
vapor. 

All of the data for any compression machine using a volatile 
liquid and its vapor can now be applied. Several problems 
will be worked out. 

PROBLEM 

As a problem in the above theory, suppose it is desired 
to keep a room at o F. with water at 60 F., and the amount 
of refrigeration is to be i ton. Investigate for wet and dry 
compression with ammonia and for wet compression with CO2 
and SO 2 . 

The temperature of the vapor in the condenser for a 10 
rise and a 10 difference will be 80 F. The temperature of 
boiling with a 5 rise in brine temperature and a 10 difference 
in temperature between brine and room and brine and vapor 
will be -25. 

AMMONIA WET 

pz corresponding to 80 

#2. . 

S2 1.0354 

*2 557-o 

*'a 53-6 

i-y (if after cooled to 70) 42.1 

pi corresponding to 25 15.61 

i. 03 M- -(-.oi 290) R R 

x\= 0.555 

1-3599 

si T-0354 

ii=g'+*r=- 59.8 +0.858X591. i =447 -2 
21=0.858X16.95 14.5 



THERMODYNAMICS OF REFRIGERATING APPARATUS 73 
Refrigeration perlb. of NHs = ii * 3 / = 447.2 42.1 =405.1. 

Weight of NHs per min. per ton of ref. = =0.49. 

405.1 

Cooling per Ib. of NH3=?2 ?V = 557-~4 2 - 1 = 5 I 4-9- 

Lbs. water per Ib. NH 3 = ^P = 5i.5 Ibs. 
10 

H.P. per Ib. NH 3 per min. = **"** = 557 ~ 447 = 2.9. 
42.42 Xeff. 42.42X0.90 

Volume per Ib. of NH 3 = 14.5 cu.ft. 

Cooling water per min. per ton = 5 1.5X0.490 = 2 5. 2 Ibs. per 

min. 

H.P. per ton of capacity = 2. 9X0.490 = 1.42. 
Displacement of piston per min. per ton with no clearance 

= i4.5X-49 = 7.i cu.ft. 

Clearance factor with 2% clearance = i +0.02 0.02 ( I "- Q |r2 

\ 15.67 

= 1.020.135=0.885. 

Displacement per min. per 'ton = -^~ =8.0 cu.ft. per min. 

0.885 

per ton. 



Refrigerating effect with friction = ^' Z =3.32. 



AMMONIA DRY 

15.6 

I.O 

1.2310 

*1 .............................. 531-3 

*>i .............................. l6 -95 

M8oF.) ....................... 153-9 

$2 ......................... ..... I.23IO 

quality .......................... 201 sup. 

2 .............................. 680 . i 

i* .............................. 53-6 

iy .............................. 42.1 



74 ELEMENTS OF REFRIGERATION 

Refrigeration per Ib. of NH 3 =z'iz 3 / = 531.3 42.1 =489.2. 

Weight of NH 3 per min. per ton of ref. = =0.407. 

489.2 



Cooling per Ib. of NH 3 = J2 ^V = 680.142.1 =638.0 B.t.u. 

Lbs. water per Ib. NH 3 =^? = 6 3 .8 Ibs. 
10 



H.P. per Ib. NH 3 per min.= 2 ~ 1 = -~- 
42.42 X. 90 42.42 X. 90 

Volume per Ib. of NH 3 = 16.95. 

Cooling water per min. per ton = 0.407X63. 8 = 25. 9 Ibs. 
H.P. per ton capacity = 0.407X3. 90 = 1.585 H.P. 
Displacement per min. per ton, no clearance 

= 0.407X16.95 = 6.9 cu.ft. 

Clearance factor with 2% clearance 



= i +0.02 0.02 ( -^^) L33 = 0.91 



Displacement per minute per ton= ^- =7.59 cu.ft. 
Refrigerating effect = 



148.8 

CO 2 WET 

pi (at -25F.)... 201. 3 Ibs. 

p 2 (80 F.) 967 Ibs. 

X2 I . O 

52 0.1508 

5l 0.1508 

Xi o. 706 

0.2927 

ii = 26.99+0.706X127.28.. 63.0 
Vi =0.451 X. 706 0.318 

iy = 26 . 21 



THERMODYDAMICS OF REFRIGERATING APPARATUS 75 

Refrigeration per Ib. of C02 = ii 4' = 63.0 26.2 = 36.8. 

Weight of CO2 per min. per ton of ref. =-2^- = 5.42. 

30.8 



Cooling per Ib. C0 2 = Z2 Z3' = 8i. 52 26.21 = 55.31. 
Lbs. of water per Ib. of CO 2 =^^ = 5.53. 

TT -r. 11 /-./-, 81X26^.0 18X2 

H.P. per Ib. CO 2 per mm. = 2 - ? = = 0.547. 

42.42X0.80 42.42 X.8o 

(80% eff. due to high pressure.) 
Cooling water per minute per ton = 5. 42 X5-53 =30.0. 
H.P. per ton capacity = 0.547X5.42 = 2.96. 
Displacement per min. per ton, no clearance 

= 5.42X0.318 = 1.72 cu.ft. 
Clearance factor i% clearance 

= i +0.01 -o.oi X ( ) 1^ = 0.076. 

\20I/ 

Displacement per minute = ^ = 1.76 cu.ft. 
0.98 



Refrigerating effect = = 2. 48. 

18.52 

This low effect is due to the peculiar properties of CO 2 
at the temperature used. At other pressures the properties 
are such that CO 2 gives a much higher refrigerating effect than 
other substances. The temperature of 85 F. is not far from 
the critical temperature of CO 2 and for this reason the results 
are as above. On the T-S diagram of Fig. 33 this is shown 
clearly by 1-2-5-6'. Plank in the Zeitschrift fur der Gesamte 
Kalte Industrie proposes that if the critical temperature is 
passed, the cooling of the superheated vapor in the condenser 
should be followed by a further compression, after which 
a second cooling is resorted to, and that this reduces the 
entropy so that the state after throttling is changed to give 
greater refrigeration. The results are shown in the table 
on the following page. 



76 



ELEMENTS OF REFRIGERATION 



Condenser Pressure, 
Atmospheres. 


Temperature of 
CO 2 at Exit from 
Condenser. 
Deg. F. 


Gain in 
Refrigeration. 
Per cent. 


Performance. 
Per cent. 


80 


91 


48 


28 


90 


101 


46 


32 


100 


III 


44 


35 



Fig. 33 shows the compression beyond the critical pressure. 
The use of the figure is similar, however, to that of the regular 




Entropy 

FIG. 33. CO2 Diagram on T.S. Co-ordinates Showing Plank's Duplex 
Compression. 

T-S diagram. i-2 II -5 II -5 ra -5 IV -6 m is the Plank cycle. The 
refrigeration under 6"'-6' is gained by the compression 5"-$'" 
and the cooling 5"'-5 IT . The cycle i/-2 / ~5 / -6 / is one near 
the critical temperature in which the refrigeration under 6 / -i / 
is small when compared with the work 7-i/-2 / -5 / -7. 

SO 2 WET 
p2 for temperature 80 59 . 7 

X2 I 00 

5 2 ! 0.3020 

iz 162.08 

iy 12.62 



THERMODYNAMICS OF REFRIGERATING APPARATUS 77 

pi for - 25 ...... . . .......... '. . . 4.98 

Si .............................. o . 3020 

.?O2O + O.CU7O 

xi=^ = .............. 0.835 

0.4062 

*i = 17.15 +176-5X0.835 ........ 130.1 

^1 = 14.13X0.835 ................. 1 1. 8 

Refrigeration per Ib. of SO2 = (^i *V) = 130.1 12.62 = 117.5. 
Weight of 862 per min. per ton of ref. = =1.695. 
Cooling per Ib. of 802=22 23' = 162.08 12.62 = 149.46. 
Lbs. of water per Ib. 802=^^ = 14.95. 



10 

H.P. per Ib. of S0 2 per min. = l62 ' o8 ~ I3 - 1 =0.84. 

42.42 X. 9 

Cooling water per min. per ton = 1.69X14.95 = 25.3. 
H.P. per ton of ref. =0.84X1.69 = 1.42. 
Clearance factor, 2% clearance 

= i +0.02 -0.02(^^)1^6 = 0.88. 
\4.98/ 

Displacement per ton of refrigeration, no clearance 

= 1 1 .80 X i .69 = 20.00. 

Displacement per ton of ref rigeration = = 22.7. 

O.oo 

Refrigerating effect = 5 = 3 .3 1 . 

With the ammonia system it was seen that 1.42 H.P. is 
required to produce a ton of refrigeration. If this engine is 
assumed to use 30 Ibs. of steam per H.P. hour and if auxili- 
aries require 20% of the steam of the main engine, while the 
boiler evaporates 9 Ibs. of steam per pound of coal, the coal 
required would be 

1.42X30X24X1.20 lbs> 



78 



ELEMENTS OF REFRIGERATION 



492 3/F 



Abs. Zero 





'"20 If'Q b' 5 Entropy 6 6' 

FIG. 34. Effect of Temperature Range on Refrigerating Effect. 



THERMODYNAMICS OF REFRIGERATING APPARATUS 79 

For ice making it takes if to 2 times the tons of ice in re- 
frigeration units, or 272 Ibs. of coal would be required per ton 
of ice. This gives practically 7! tons of ice per ton of coal. 
This is quite a common figure and one to keep in mind. Of 
course, as can be seen from the diagrams, the temperature 
range, or particularly the temperature of the cooling water, 
plays an important part in the economy of a station. Thus in 

Fig. 34 if 1234 represent a cycle, the performance is 

If, now, the temperature of the cooling water can be lowered 
to 2 '-3', the work 1-2-3-8 is decreased to i / -2 / -3 / -8 and the 
refrigeration is increased to 5 '-4'-! '-6'. The same effect on 
work is noticed if the lower temperature can be made higher. 
Thus, if the back pressure is raised to i"-8", then the work is 
decreased materially and there is an increase in refrigeration. 
Hence the refrigerating effect is increased. Before telling the 
refrigerative performance or the cost of producing ice or re- 
frigeration, the temperature range must be known. The smaller 
the range of temperature the more effective the apparatus. 
Thus 7^ tons of ice per ton of coal is often reduced to 6 and 
may reach 15, depending on the temperature ranges. More- 
over, if the engine driving the compressor be very efficient, 
and use 12 Ibs. of steam per H.P. hour instead of 30 Ibs., the 
output would be increased very materially. Reports have been 
made that in Europe results as high as 28 tons of ice per ton 
of coal have been obtained. This is a matter of temperature 
range and efficiency of engine. In many cases the steam of 
the engine is used to give distilled water for ice making, and 
unless evaporators, which complicate the apparatus, are used, 
a low-grade engine is required to give the necessary amount 
of water. The usual amount in such plants is 6 to 9 tons 
of ice per ton of coal. If raw water is used, then an engine 
of greater efficiency may be used, and the result will be in- 
creased to 10 or 15. With a gas-producer engine this figure 
is raised to 20 tons of ice per ton of coal. 

The common form of absorption apparatus is that using 
aqua ammonia. Before considering the operation of the 



80 ELEMENTS OF REFRIGERATION 

apparatus, certain physical phenomena must be noted and 
quantitative relations given. A solution of 30% NHs and 
70% water is said to be of 30% concentration. The temperature 
at which a solution of liquor of given concentration will boil, 
depends upon the pressure on the liquor. The relation between 
the pressure and temperature has been determined experi- 
mentally by Mollier and plotted in curves and tabulated, 
The results may be closely approximated in the form of an 
equation similar to the method used by Macintire. 

-^ = 0.00471^+0.655 (80) 

/sol 

Tsat = temp, of saturated ammonia corresponding to the 
pressure; 

Tsoi = temp, of boiling; 
#=per cent of NHs in solution = per cent concentration. 

This equation has been derived from the results of exper- 
iments of Mollier and Perman as given by Lucke. The tabular 
values given do not give uniform changes in certain increments, 
so that there must be some error in these values. The equation 
will give results within i% of the tabular values. 

When the liquor is heated to drive off the ammonia, both 
ammonia vapor and water vapor leave the liquor. The partial 
water vapor pressure has been assumed by Spangler to be the 
steam pressure at the temperature considered, multiplied by the 
ratio of the number of mojecules of water in a certain amount 
of liquor to the total number of molecules of liquor. Thus 

= relative number of NHs molecules, 
' - = relative number of IbO molecules. 

Io 

Hence 

100 x 

Partial steam pressure = p = p -2?, (81) 

* x ioo-a r 1700+* 

17 18 
p = steam pressure at given temperature. 



THERMODYNAMICS OF REFRIGERATING APPARATUS "81 

The values given by this method of computation agree well 
with the results of Perman as stated by Lucke. 

If i Ib. of ammonia vapor be absorbed by 200 Ibs. of water, 
it will be found that 893 B.t.u. of heat are developed. This 
would be the same if more water were used, and it is called the 
heat of complete absorption. If, now, a smaller quantity of 
water were used, it would be found that less heat would be 
liberaced. This is known as the heat of partial absorption. 
If this solution be added to enough water to make the dilution 
one in two hundred, the remaining heat of the 893 heat 
units would be liberated. This is called the heat of complete 
dilution. 

Berthelot has found that the heat of complete dilution 
in B.t.u. is 142.5 times the weight of ammonia per pound 
of water. This has been checked by Thomsen with a wider 
range of experiments. This gives, then 

Heat of complete dilution = 142.^ - . 

* 



This gives for the heat of partial absorption 



= 893- 142.5 (82) 



This is the heat when i Ib. of ammonia is dissolved in 
sufficient water to bring the concentration to x%. 

If - Ibs. of ammonia are absorbed, 
100 



is the heat generated in producing i Ib. of solution of strength 
x by adding ammonia to water. 

The amount of water in i Ib. of mixture of strength x is 



-' and the amount of ammonia is . 

JOO 100 



82 ELEMENTS OF REFRIGERATION 

The amount of water is - , and the ammonia weighs 
100 

x' 

- if the i Ib. of mixture is of concentration x'. 
loo 

The amount of ammonia to bring the water in the first 
case to concentration x' is 



100 X 100 



100 100 x' loo o/ioo' 

1 00 

or the additional ammonia to change strength from x to x' is 



- x V = addition of NH 3 . (84) 



IOO X IOO IOO 



The heat produced by this is the difference in the two 
heats of partial absorption. 



ioo-x 



If this is divided by the weight added, the heat per pound 
of NHs added to change the strength from x to x' is given. 



. . (85) 



When i Ib. of ammonia is liberated to change the con- 
centration from x' to x, more heat is required than that given 
above, because the water vapor is driven off with the ammonia 
and, moreover, the vapors are superheated when driven off 
from a liquor. 

The 893 B.t.u. is the heat developed from the absorption 
of the vapor. If a liquid is used, 530.7 B.t.u. above 32 F. 
will have to be added to the heat to care for the generation 
of the vapor. This would mean that the heat developed 



THERMODYNAMICS OF REFRIGERATING APPARATUS 83 

would be less, by this quantity, if liquid ammonia is added 
to water. 

The specific heat of aqua ammonia will be taken as unity. 

The specific gravity of aqua ammonia is given by 



. . . . (86) 



100 io,ooo 



The weight of weak liquor to absorb i Ib. of ammonia vapor 

and change its strength from x to x' is given as follows: 



100 "100 



PROBLEM FOR ABSORPTION APPARATUS 

Suppose the water available for cooling is at 60 F., and it 
is desired to operate the absorption machine with steam at 5 
Ibs. back pressure. 

The temperature of condensation with a 15 rise in temper- 
ature of the cooling water and a 10 temperature difference 
would be 85 F., and this would give an absolute pressure 
of 167.4 Ibs. per square inch for the ammonia. The pressure 
in the generator to allow for the pressure drop in the separator, 
rectifier and analyzer would be 169 Ibs. 

The temperature corresponding to an absolute steam pres- 
sure of 20 Ibs. is 228 F. Allowing 6 difference in the coils of 
the generator would give a boiling temperature of 222 F. 

The minimum concentration under 169 Ibs. and 220 F. 
would be given by (80) : 

8s. 6+459. 6 

= 0.004712+0.655, 
222+459.6 

2 = 30.7%. 



84 ELEMENTS OF REFRIGERATION 

If higher pressure steam were available, say 25 Ibs. gauge, 
the minimum value of x would be 20.4%. 

85.6+459.6 
267.2+459.6 



This would increase the ammonia yield and cut down the 
amount of liquor to be handled. 

If the cold room is desired at o F. with a 10 fall in the 
brine temperature and 10 temperature differences, the brine 
would have to be at 20 and the ammonia in the expansion 
coil would be at 30 F. This means an absolute pressure of 
13.56 Ibs. per square inch. The absorber pressure would then 
be a little lower, about 13 Ibs. If it is desired to get a solution 
of 40% concentration in the absorber, the limiting temperature 
is found as follows: 

-31.5+459.6 = .oo 47I X40+o.6ss, 

'sol 

^-0.843, 



Since it is not possible to maintain this temperature with 
cooling water at 60 F., a lower concentration must be carried. 
Assume that a temperature of 80 F. could be maintained. 
Then 

428.1 



It is, of course, impossible to have this, as the absorber would 
not operate to give the proper concentration. 

Suppose then that a 5 rise is permitted in the brine and 



THERMODYNAMICS OF REFRIGERATING APPARATUS 85 

5 drop in heat transfer. This would mean a larger brine pump 
and larger coils. The temperature of the ammonia would 
then be 15 F., and the pressure would be 20.46 or 20.00 
in the absorber. 

This gives for 40% concentration. 

- .5.9+459.6 



This might be possible. It will be required, however, to 
use 70, which gives, as the limiting value of x, 



The amount of weak liquor allowed to flow per pound of 
ammonia absorbed is, by (87) 

= 7.25 Ibs. 



39-1-30-7 

The amount of strong liquor pumped will be 8.25 Ibs. per 
pound of anhydrous ammonia absorbed or evaporated in the 
refrigerator or expansion coil. This quantity is a little high, 
due to the fact that the limits of pressure are close. The 
usual practice is to have between 7 and 8 Ibs. pumped per 
pound of ammonia. From the specific gravity of aqua ammonia, 
the volume of the liquor for a given amount of refrigeration 
could be found and from this the displacement of the pump. 

It will be well to find the temperature of boiling for a 39.1% 
solution under the pressure of the analyzer to see if some of 
the liquor will boil on entering this part of the system. At 
the top of the analyzer the pressure may be taken as 169.5 
Ibs. The temperature of boiling is given by 



651 = 191 F. 



86 ELEMENTS OF REFRIGERATION 

As soon, then, as the strong liquor is heated to 191 F., 
vapor will begin to come off. 

Another computation, which can be made now, is the 
possible rise of temperature of the strong liquor in passing 
through the interchanger ; 8.25 Ibs. of strong liquor pass 
one way, while 7.25 Ibs. of weak liquor pass the other way. 

If the efficiency of the interchanger is assumed to be 90% 
and the strong liquor is not passed to the rectifier before entering 
the interchanger, it will be seen that the interchanger will cool 
off the weak liquor so that there is no need of a weak liquor 
cooler. The temperature of the weak liquor entering is 222 
F., and that of the strong liquor is 70. The weak liquor is 
assumed to be cooled to 76 F. 

0.90[222.0- 76] X 7- 25 = (^-70)8.25, 



Radiation, io% = 95.4 B.t.u. 

Of course, if 76 is assumed to be too high a tempera- 
ture at which the weak liquor enters the absorber, with 
water in the coil at 60, this may be cooled down to 65 in 
a weak liquor cooler before entering the absorber. In any 
case this heat will be removed by the cool water in the 
absorber cooling coil or in this coil and the weak liquor cooler 
coil together. 

The various conditions will now be investigated, starting 
with the entrance into the condenser. At this point it is found 
by some engineers that the best results are obtained if the 
ammonia is superheated about 20 to 30. This means that 
the temperature of the ammonia is 105 F. at this point and 
that the total pressure is 167.4 Ibs. The strength of a solu- 
tion boiling under these conditions is given by 

^4^6=0.00471^+0.655, 
105+459.6 



THERMODYNAMICS OF REFRIGERATING APPARATUS 87 
By (81) the partial steam pressure is 

1700 17X6^ 

/> = i.ioiX -^ -=0.371 lb. 

170x5+65 

The ammonia vapor pressure = 167.03 Ibs. 

The saturation temperatures are 71 and 84.9, given 
34 F. of superheat for the water vapor and 20.1 for the 
NH 3 . 

The volume of i lb. of superheated NHs is 1.89 cu.ft. and 
the weight of the superheated steam for this volume is about 
0.002 lb., a negligible quantity. 

For convenience in parts of the problems it will be well 
to tabulate these conditions in the following form: 

CONDITIONS AT ENTRANCE TO CONDENSER 

Concentration, x 65% 

Temperature 105 F. 

Pressure steam 37 

Pressure ammonia 167 . o 

Saturation temperature, steam 71 F. 

Saturation temperature, ammonia 84. 9 F. 

Superheat, steam 34 F. 

Superheat, ammonia 20. i F. 

Specific volume, steam 842 cu.ft. 

Specific volume, ammonia i . 89 cu.ft. 

Heat content, steam 1 102 . o B.t.u. 

Heat content, ammonia 573 . 3 B.t.u. 

Weight of water vapor per lb. of ammonia =0.002 lb. 

842 

If a temperature of 105 F. is used in the rectifier the water 
coming from the condenser at 70 would be amply cool for this 
work. The amount of supply must be regulated to bring 
the temperature to 105. 

The vapors entering the rectifier will be assumed to be 
a little lower than 185.5, as tne rectifier liquor may reduce 



88 ELEMENTS OF REFRIGERATION 

this temperature. Take 180 as the first assumption. The 
pressure here may be 168.5 Iks. an d x is given by 



The partial steam pressure'is 



CONDITIONS AT ENTRANCE TO RECTIFIER 

Concentration ............................. 41.8 

Temperature .............................. 180 F. 

Pressure, steam ........................... 4.27 

Pressure, ammonia ......................... 164. 23 

Saturation temperature, steam ............... 155 . 5 F. 

Saturation temperature, ammonia ............ 83 .9 F. 

Superheat, steam .......................... 24 . 5 F. 

Superheat, ammonia ....................... 96 . i F. 

Specific volume, steam ...................... 89 . 7 cu.f t. 

Specific volume, ammonia ................... 2 . 29 cu.ft. 

Heat content, steam ........................ 1140.4 B.t.u. 

Heat content, ammonia ............... ..... 621 .4 B.t.u. 

Weight of water vapor per Ib. of ammonia |^ = 0.026 Ib. 

89.7 

It is seen that there has been some condensation in the 
rectifier, as the moisture per pound of ammonia at entrance is 
0.026 Ib., and at exit it is 0.002 Ib. This condensation leads 
to the formation of liquor, as the water will absorb ammonia 
to 65% concentration. To find the amount of ammonia M 
entering the rectifier the following equation is used: 

[(o.o26)M-o.oo2 X i] = M- 1, 



M => = 1.045 Ib. 
.9516 



THERMODYNAMICS OF REFRIGERATING APPARATUS 89 

The absorption of 0.045 lb. f ammonia will yield 

0.045 X-^^ = 0.07 Ib. of solution of 65% concentration and 
65 







temperature 105. 

The moisture with 1.045 Iks. f ammonia is 1.045X0.026 
= 0.027 lb. 

The rectifier has the following weight balance: 

Weight Balance Rectifier 
Entering: 

Ammonia vapor ................ 1 . 045 Ibs. 

Water vapor ................... 0.027 

1.072 Ibs. 
Leaving : 

Ammonia vapor ................ i . ooo Ibs. 

Water vapor ................... o . 002 

Liquor ........................ o. 070 

1.072 Ibs. 

The best way to study the heat required in any part of 
the apparatus is to find the sum of all the heats entering and 
leaving. The heat entering with a vapor would be the intrinsic 
energy plus the work done in forcing the vapor in. The sum of 
these two would be the heat content. Where there are several 
vapors together, the sum of the heat contents will give the 
heat entering or leaving. 

For liquids the heat of the liquid must be considered. In 
addition the heat of absorption must be considered as a neg- 
ative amount of heat, because the heat generated by this 
absorption has been removed before the solution reached this 
point. 

Since the heat content is figured above liquid at 32 and 
the heat of absorption is for the absorption of gas, the liquid 
may be changed to a 32 liquid datum plane by adding to 
the negative heat of absorption MXiu.7 or 530.7^ as the 
heat of atmospheric pressure. 



90 ELEMENTS OF REFRIGERATION 

The sum of these will give the total heat at any point. 

Thus, if M a , M s , and MI are the weights of ammonia vapor, 
steam, and liquor, and the strength of the liquor is x, the fol- 
lowing is the scheme for the heat at this point: 

Energy in ammonia = M a i ; 
Energy in steam =M s i; 

Heat of absorption = M ,( 8.93* Ll^L j . 
\ " loo */ 

Heat of atm. pressure = 530. 7 MX; 
Heat in liquor =Miq f . 

The following heat balance will then be found: 

Heat Balance Rectifier 
Entering : 

Energy in ammonia .............. 1.045X621.4= 649/0 

Energy in steam ................. 0.027X1140.4= 30.8 

679.8 
Leaving: 
Energy in ammonia ............... 1.000X573.3= 573.3 

Energy in steam ................. 0.002 X 1 102.0 = 2.2 

Heat of liquid of liquor ......... 0.07 X (105 32) = 5.1 

580.6 
Heat of partial absorption 



Heat of condensed vapor at atmospheric pressure 

= 0.045X530.7= 24.1 
Heat removed in rectifier 

= 679.8-580.6+28.3-24.1 = 103.6 B.t.u. 

Lbs. of water from 68 to ioo = I 3 ' . . . . . . = 3 . 24 

32 

Now, if 8.25 x lbs. of liquor of strength 39.1% be mixed 
with 0.070 Ib. of strength 65%, the mixture will be of strength 

8.25X39.1 +0.070X65 = ~ 
8.32 



THERMODYNAMICS OF REFRIGERATING APPARATUS 91 

The heat generated by the dilution of the stronger liquor 
and the concentration of the weaker is given by 



8,48,3x3,3-1 






= 2620 (2575 + 28.6) = 16.4 B.t.u. 

The temperature of the mixture is then found as follows: 
t 8.25X153.5+0.070X73 + 16.4^ o F 

t = 186.5 F. 

Although 1 80 was assumed as the temperature at entrance, 
there will be no recomputation of this point, as the temperature 
186.5 may be decreased by radiation. The value 0.9 taken 
as the efficiency of interchange is not known close enough to 
warrant recomputing this. The temperature of the liquor of 
strength 39.3 will be taken -as 180 F. This will not begin to 
boil until it reaches a lower point in the analyzer. The addi- 
tional radiation will equal 6.5X8.32 = 54.1. In the analyzer at 
the upper end there are 1.045 Iks. f superheated vapor leaving 
with 0.027 Ib. of water vapor, and entering at this point are 
8.32 Ibs. of liquor of 39.3% concentration. At the lower end 
of the analyzer the conditions of temperature and pressure are 
as follows: 

CONDITIONS AT ENTRANCE TO ANALYZER 

Boiling temperature ..................... 222 F. 

Concentration .......................... 30 . 7% 

Pressure, total .......................... 169 Ibs. 

, 1700 17X^0.7 
Steam pressure ....... 17.86 '- = 12. 15 

I730-7 
Ammonia vapor pressure ...... 169 12.15 = 156.85 

Sat. temp, of steam ..................... 202 . 5 F. 



92 ELEMENTS OF REFRIGERATION 

Sat. temp, of ammonia 81 . i F. 

Steam superheat 19 . 5 F. 

Ammonia superheat 140. 9 F. 

Volume of i Ib. of ammonia 2 . 59 cu.ft. 

Volume of i Ib. of steam 33 - cu.ft. 

Heat content, ammonia 646 . 2 B.t.u. 

Heat content, steam H57-4 B.t.u. 

Weight of steam with i Ib. of NH 3 ^. . . = 0.0785 Ib. 

33- 

In passing up through the analyzer the vapor is changed, 
so that per pound of NHs passing there is 0.026 Ib. of water 
vapor present at outlet. The original amount was 0.0785 Ib. 
of vapor per pound of ammonia. This condensation absorbs 
enough ammonia to make the strength 41.7%. By the method 
used with the rectifier the amount of ammonia absorbed is 
0.04 Ib. per pound of ammonia leaving, and the amount of 
liquor formed is 0.0957. The steam condensed is 0.0557 Ib. 

The total amount of ammonia at entrance being M, the fol- 
lowing holds: 

M 0.04^ = i .045 , 

M = 1.085. J 

At entrance there are 1.085 Ibs. of NHs. The liquor formed 
is 0.0957 Ib. Hence the liquid dropping back into the analyzer 
will be 

8.25 Ibs. of strong liquor of strength 39.1%, 
0.07 Ib. of strong liquor of strength 65%, 
0.096 Ib. of strong liquor of strength 40.7%. 
This gives. 8.416 Ibs. of liquor of strength 39.3%. 

If there were no evaporation in the analyzer, this liquid 
would fall into the generator, but because there is heat added 
to liquor by superheated vapors passing upward some ammonia 
is driven off. Assume that the temperature of the liquor is 
raised to 192 F. There must be a balance if this is the 
case. 



THERMODYNAMICS OF REFRIGERATING APPARATUS 93 

CONDITIONS AT 192 F. AT BOTTOM OF ANALYZER 
Pressure .............................. 169 Ibs. 

Temperature, assumed. . . ............... 192 F. 

Concentration 



Steam pressure ...... = 5.84 



Ammonia pressure ............ 169 5 . 84 = 163 . 16 

Saturation temperature, ammonia ...... . . 83. 5 F. 

Saturation temperature, steam ........... 169 F. 

Superheat, ammonia .................... 108 . 5 F. 

Superheat, steam ...................... 23 F. 

Specific volume, ammonia ............... 2 . 36 cu.f t. 

Specific volume, steam .................. 66.3 cu.ft. 

Heat content, ammonia ................. 628 . 5 B.t.u. 

Heat content, steam. ... ................ 1145 . 5 B.t.u. 

Weight of water vapor per Ib. of NH 3 . . |^- = o . 035 

00*3 

The ammonia set free, M, in changing from 39.3% to 
38.8%, is given by 

(8.39X0.393-^)^ = 8.416-1.035^, 

M ^8.42(0.393-0-388) ^0.421 __ Q 
i -(1.035)0.388 0.598 

The amount of water vapor leaving is 
0.070X0.035 = 0.002. 

The amount of liquor falling into the generator equals 
8.4160.0700.002 = 8.348 Ibs. 

The amount of ammonia vapor coming from the generator 
amounts to 

1.0850.070 = 1.015 Ibs. 



94 ELEMENTS OF REFRIGERATION 

The water vapor leaving amounts to 

1.015X0.0785=0.080 Ib. 

The weak liquor left in the generator is equal to 
8.348-1.072 = 7.253. 

This should amount to 7.248, since 0.002 Ib. of water enters 
the absorber with the ammonia. 

Weight Balance for Analyzer 
Entering: 

f ammonia 1.015 

From generator \ 

( water vapor 080 

From rectifier, liquor 070 

From interchanger, liquor 8. 250 

' 9-4I5 
Leaving : 

.- f ammonia.. . 1.04^ 

To rectifier ' 



water vapor 0.027 

To generator, liquor 8 . 348 

9-418 

Heat Balance for Analyzer 
Entering: 

ammonia. 1.015X646.2= 656.0 



From generator . 

' steam. . .0.080X1157.4= 92.6 

From rectifier and interchanger 
Heat of liquid of liquor 8. 320 X (180 32) = 1230.0 



1978.6 
Heat of partial dilution, 



= 2620= 2620 
Heat of vapor atm. pressure 

8.32X0.393X530-7 



THERMODYNAMICS OF REFRIGERATING APPARATUS 95 

Leaving: 

,._ f ammonia 1.045X621.4= 640.0 

To rectifier \ 

(steam 0.027X1140.4= 30.8 

To generator, 

Liquor, heat of liquid 8.348[i92 32]. =1335.0 



2014.8 
Heat of partial dilution 

-8. 3 48[8.93X 3 8.8- 1 -^** 8 - 8 '] = -2518 



Heat of vapor atm. pressure 

8.348X0.388X530-7 = 
Heat to drive off ammonia 2620 2610= 10 B.t.u. 

Excess leaving 1991.8 1957.3 = +34. 5 B.t.u. 

Heat of atm. pressure .... 17101740= 30 B.t.u. 

In other words there is an excess of 26.2 B.t.u. and con- 
sequently the liquor cannot be warmed to 192. 

Try 188. 

Pressure 169 Ibs. 

Temperature assumed 188 F. 

Concentration 39-9 

This is stronger than the original liquor, so there can be 
no evaporation. 

Try 190. 

Pressure 169 

Temperature assumed 190 

Concentration 39.3 

This is possible, as the liquor is just heated to its limit. 
Hence all will fall into the generator giving as- the weight balance 
the following: 



96 ELEMENTS OF REFRIGERATION 

Weight Balance for Analyzer 
Entering: 

From generator, 
Ammonia. . . ; ........................ i . 085 

Water vapor ......................... o . 083 

From rectifier and interchanger, 
Liquor .................. ........... 8.320 

9-488 
Leaving: 

To generator, liquor (8.32+0.096) ....... 8.416 



To rectifier aramona 



[ steam .................... 0.027 

"9^88 
Heat Balance 
Entering: 

From generator { ammonia. I .o8 5 X6 4 6. 2 = 700.0 
[steam.. 0.083X1157.4= 96.1 
From rectifier and exchanger, liquor 



2026 . i 
Heat of partial absorption ........... = 2620.0 

Heat at atm. pressure, 



Leaving: 

To generator, liquor ...... 8.42(i92--32) = 1329.0 

To rectifier I ammonia ..... 1.045X621.4= 650.0 

j steam ....... 0.027X1140.4= 30.8 

2009.8 
Heat of partial absorption 

-^X 2620.0 =-2650 
8.32 

Heat at atmospheric pressure 

8.42X0.393X530.7 = 1760 

There are 12 B.t.u. entering in excess and there are 19 
B.t.u. given off to care for the heat in large amounts of liquor. 
To allow for condensation of vapor above atmospheric pressure, 
there will be a deficiency of 25 B.t.u. This gives 22 B.t.u. 
in excess. This would raise the liquor 3 degrees, but this is 



THERMODYNAMICS OF REFRIGERATING APPARATUS 97 

impossible as 192 is too high. Suppose 190.8 is tried. Since 
at 192 there are 26.2 B.t.u. in excess leaving, and at 190 there 
are 22 B.t.u. in excess entering. 

Pressure 169 

Temperature 190.8 

Concentration 39 . i 

Steam pressure.. . . .o.^o ^^= 6.2 

1739 

Ammonia pressure 169 6.2= 162.8 

Saturation temperature, ammonia. ... 83.3 F. 

Saturation temperature, steam 171. 5 F. 

Superheat, ammonia 107 . 5 F. 

Superheat, steam 19.3 F. 

Specific volume, ammonia 2 . 36 

Specific volume, steam 62 .00 

Heat content, ammonia 627 . 6 

Heat content, steam 1 144 . 4 

Lbs. of water vapor per Ib. of NH 3 -^- = .038 

02.0 

NH 3 set free. . .S.J (0-393-0.391) \ = Q O2g 

\i- 1.038X0.3917 
Steam set free ,0.028X0.038= o.ooi 

Weight Balance or Analyzer (^d Assumption) 
Entering: 

From generator, 

Ammonia i .085 0.028 = 1-057 

Steam 0.083 0.001= 0.082 

From rectifier and interchanger, 
Liquor 8 . 320 

9-459 
Leaving : 

To generator, liquor 8.4160.029= 8.387 

T. ,/- I ammonia. . . . = i 04 <c 
To rectifier \ 45 

steam = 0.027 

9-459 



98 ELEMENTS OF REFRIGERATION 

Heat Balance for Analyzer 
Entering : 

From generator, 
Ammonia ............. 1.057X646.2 = 683.0 

- Steam .............. 0.082X1157.4= 94.8 

From rectifier and interchange^ liquor = 1230 

2007 . 8 
Heat of partial absorption 



Heat of atmospheric pressure 

8.32X0.393X530-7= 1735 
Leaving: 

To rectifier, 

Ammonia ............. 1.045X621.4= 650.0 

Steam ............... 0.027X1140.4= 30.8 

To generator, liquor 8.387(192.8 32)= 1330.0 



2010. 
Heat of partial absorption 



Heat of atmospheric pressure 

8.387X0.391X530.7= 1735 
Heat at atmospheric pressure 

i735- I 735= o 

Heat of concentration. . . 2620 2625 = 5 B.t.u. 

Excess heat leaving. .2010.8 2007.8= 3 B.t.u. 

Excess heat, entering .............. = 2 B.t.u. 

If 190 gave 22 B.t.u. excess entering and 190.8 gave 2 
B.t.u. excess entering, the value of 190.85 is probably correct. 
It is not worth working as close as this and the 22 B.t.u. 
excess entering may be assumed to be cared for by radiation, 
giving the second computation as the one required. 

The investigation of the generator now follows. 



THERMODYNAMICS OF REFRIGERATING APPARATUS 99 

Weight Balance for Generator 
Entering: 

From analyzer, liquor 8.416 Ibs. 



8.4i61bs. 
Leaving : 

To analyzer, 

Ammonia i . 085 

Steam o . 083 

To exchanger, 

Liquor 7 . 248 



Heat Balance for Generator 
Entering : 

From analyzer, 

Liquor ............. 8.416(190 32) = 1329 

Heat of partial absorption ......... = 2650 

Heat of atm. pressure 

3.416 Xo.393X53-7 = J? 60 
Leaving : 

To analyzer, 

Ammonia ............. 1-085 ^646.2 = 700 

Steam ................. 072X1154= 96.1 

To interchange'r, 

Liquor ............ 7.248[222.9~32]= 1375.0 

2171. i 
Heat of partial absorption 



Heat of atm. pressure 

7. 248 X. 307X530.7= 1180 
Heat for difference in heats of partial 

absorption ........... 2650 1845 = 805 

Heat excess in leaving. 2171.1 1329= 842.1 
Heat in atm. pressure. ..11801760= 580 

1067 . i 



100 ELEMENTS OF REFRIGERATION 

Pounds of exhaust steam at 20 Ibs. absolute pressure, of 
quality 0.85 required to produce this heat is given by 

Lbs. of steam = * ''* =1.32 Ibs. 
.85X959.4 

If 10% radiation is assumed the steam will be 1.4 Ibs. 

At the discharge of the condenser at 85 F., the pressure 
is 167.4 Ibs. and the strength of the solution that can be formed 
is, by (80), 

1=0.0471^+0.655, 



This result is impossible, and, moreover, the equation is 
not true for more than 50% concentration. The condition of 
the liquor is not known. The quantity formed in any case 
is not large, so it will be assumed that the strength is 50%, 
and hence on the condensation of 0.002 Ib. of water, the liquor 
formed will be 0.004 Ib. This gives the following weight 
balance. 

Weight Balance for Condenser 
Entering: 

From rectifier, 
Ammonia ............................ i . ooo 

Steam ............................... 0.002 

1.002 
Leaving: 

To throttle valve, 
Liquid NH 3 .......................... o. 998 

Liquor .................. . ........... o . 004 

i. 002 
The heat balance is as follows: 



THERMODYNAMICS OF REFRIGERATING APPARATUS 101 

Heat Balance for Condenser 
Entering : 

From rectifier, 

Ammonia I -oooX573-3 = 573.3 

Steam.. ..0.002X1102.0= 2.2 



T . 575-5 

Leaving: 

To throttle valve, 
Liquid ammonia ........... 0.998 X 59.4 = 59 . 1 

Liquor ................. 0.004(85 32) = 0.2 

Heat of partial absorption 



Heat of atm. pressure .... 0.002 X 530.7 = 1.6 



59-4 
Heat removed ............ 575.5 - 59.4 =516.1 B.t.u. 

Lbs. of water heated from 60 to 75 per 
Ib. of ammonia entering condenser 

.'.. -34.46 IDs. 



(If water from 68 to 75 is used, the amount required will 
be 73.7 Ibs., or the water from the absorber could be used in 
the condenser.) 

EXPANSION OR THROTTLE VALVE AND EXPANSION COIL 

This action is constant heat content action. Hence i after 
expansion is that for the liquid at 85 or 59.4 B.t.u. The heat 
content for dry ammonia at 15 is 534.3 B.t.u. Hence the 
refrigeration produced is equal to 

0.998(534.3 - 59.4) -0.004(85 - (- 15)] =473-5- 

If 10 B.t.u. 's are assumed for leakage, this gives 463.5 
B.t.u. of heat abstracted in the expander per pound of am- 
monia entering the condenser. 



102 ELEMENTS OF REFRIGERATION 

The number of pounds of ammonia per minute per ton 
of refrigeration is 

^ 2 =0.430 lb. 
463-5 

ABSORBER 

Weight Balance for Absorber 
Entering: 

From Expander, 

Ammonia o . 998 

Liquor o . 004 

From interchanger, 

Liquor 7 . 248 

- 8.250 
Leaving: 

To jnterchanger, 
Liquor 8 . 250 

8.250 

Heat Balance of A bsorber 
Entering: 

From expander, 

Ammonia 0.998X534.3 = 533.2 

Liquor. . o.oo4X( 15 32) = o. 2 

Heat of partial absorption 



Heat at atm. pressure ................ = 1.6 

From interchanger, 

Liquor ............... 7.248x(y6 32) =319.0 

Heat of partial absorption ............ = 1845 

Heat of atm. pressure ................ 1180 

Leaving: 

To interchanger, 

Liquor ................ 8.25 X(yo-32) =313 

Heat of partial absorption 



Heatof atm. pressure 8.25 Xo.39i X 530.7 = 1708 



THERMODYNAMICS OF REFRIGERATING APPARATUS 103 
Heat entering -heat leaving 



+[2580- 1845 -I- 5] -[1708-1180- 1.6] 
-5-526.4 = 746.i B.t.u. 



If 60 water enters and is raised to 68 F. in the cooling 
coil, the cooling water required will be 

G = ^ = 93-25 Ibs. per Ib. 

This is excessive and in practice a greater range of tem- 
perature would be used. This would reduce the quantity. 

Work of Pump 
The work done in the pump is given by 



778 



(169 20.00)144X8.25 



lOOOX 100 10,000' -I 



= 4.18 B.t.u. 



This heat is added by the pump and is cared for by radi- 
ation. The following heat balance is made: 





Heat Added. 


Heat Taken away. 


Radiation. 


Generator 
Analyzer 
Rectifier 


1067 . I 


103 6 


22.0 






516 T 




Expander 
Absorber 
Pump 


463.0 
4-2 


746.1 


10. 

(-105.8 

1 4 2 








I 54.0 





1536.8 


1365.8 
176.0 


176.0 






1543.8 





104 



ELEMENTS OF REFRIFERATION 



If i tons of refrigeration are required per ton of ice, this 
apparatus would require 

1.5X0.43X24X60 = 930103. 

of ammonia entering the condenser per day. 

The steam needed for this would be 930X1.4 = 1305 Ibs. 
Thfe would require the exhaust of a 21 H.P. engine to supply 
the steam 



If the steam were supplied by a boiler, the coal required would 



be 



1305 
10 



130.5 Ibs. The ice per pound of coal would be 





130-5 



15- 
5 



In practice these plants yield from 9 to 10 tons of ice per 
ton of coal supplied. In a test by N. H. Hiller, 60 tons of ice 
required 3890 Ibs. of steam per hour. Assuming that this high 
pressure steam is made at the rate of 8 Ibs. per pound of coal, 
the coal required for 60 tons of ice would be 11,670 Ibs. or 5.8 
tons. This gives a value of 10.3 tons of ice per ton of coal. 
The steam used for this apparatus could have been .the 
exhaust steam from an engine, and consequently the full coal 
should not be charged to ice-making. 

To give some comparative figures from the problems in this 
chapter, the results have been collected in the following table: 





2 
g.^ 


1 


I 


S3 


M. 





:l 


1 






g 


1 


ID . 


,3 . 


Ill 


Safe 


| 


is 






[itrance 1 
Compre 


;aving te 
Cooler. 


8 


II 


l|l 

.So 


11 
JS3 


? 


OH 

il 


d 

w 

"S 




M 


J 


*j 


< 


Q 


p 




j 


(2 




F. 


F. 












Lbs. 




Air, atmospheric 


10 


70 


58.8 


14-7 


103.9 


82.2 


4-95 


24.4 


o-95 


Air, dense 


10 


70 


235-2 


58.8 


26.0 


20.5 


95 


24.4 


o-95 


Ammonia, wet 


-25 


80 


153-9 


15-6 


8.0 




42 


25-2 


'3-32 


Ammonia, dry 


-25 


80 


153-9 


15-6 


7.0 




-58 


25-9 


2.96 


CO 2 , wet 


-25 


80 


967.0 


201.3 


1.76 




.96 


30.0 


2.48 


SOj, wet 


-25 


80 


59-7 


5-o 


22.7 




43 


25-3 


3-3i 



THERMODYNAMICS OF REFRIGERATING APPARATUS 105 

The refrigerant to be used is determined by the designer 
of the plant. Each has certain advantages. Air is the cheapest 
of all, but its properties are such that large displacements 
are necessary, even with dense-air machines, and for .ordinary 
temperature ranges the refrigerating effect is small. Sulphur 
dioxide and ammonia are objectionable on account of danger 
to life and property in case of breaks in the system. Carbon 
dioxide is not objectionable from this cause. The CCb and 
SO2 are much cheaper than ammonia; when the pressure range 
is considered it is found that carbon dioxide requires excessive 
pressures on both sides of the system, thus necessitating steel 
cylinders, special packings, heavy piping and fittings, but a 
small size compressor. The pressures with sulphur dioxide are 
not great and with ammonia, although the pressure is high 
on the upper side, it is not so high as to require special con- 
structions. The sulphur dioxide compressor is large as com- 
pared with the ammonia compressor. Carbon dioxide is near 
the critical temperature at ordinary water temperatures, and 
this causes certain changes to be made. As was shown on 
Fig. 33, this substance may be operated above the critical 
point: Ammonia is the most common substance employed, 
but there is a tendency to use carbon dioxide to a greater 
extent than formerly. 

Experimental runs have shown that these* substances give 
about the same practical results. The 862 and NH 3 corrode 
metals slightly and C02 and SCb machines being nearer than 
NHa to their critical temperatures, will not cause excessive 
pressure if the condenser-water should fail, as has happened 
with NHs, causing rupture in the system. NHa with oil forms 
a combustible, which cannot be said of SO2 and C02. Carbon 
dioxide can be brought in contact with any metal, while NHa 
and 862 must be kept in contact with iron and steel only. 

Mixtures of CO2 and SO 2 have been tried. 

Methyl and ethyl alcohol and methyl chloride have been 
used as refrigerants. 

In refrigeration, 2 gals, of water per minute are generally 
required per ton of refrigeration. 



106 



ELEMENTS OF REFRIGERATION 



The effect of temperature range is seen by the following 
table, given by Thomas Shipley in the Bulletins of the York 
Manufacturing Co.: 

VOLUMETRIC EFFICIENCY, DISPLACEMENT PER MINUTE PER TON AND COMPRES- 
SOR HORSE-POWER PER TON FOR YORK SINGLE-ACTING COMPRESSOR. 





Suction Pressure and Temperatures of Saturation. 


High Pressure by 
Gauge and Temp, of 


5 Lbs. Gauge or 
-17-5 F. 


10 Lbs. Gaug 
-8.05 F 


e, or 


15.67 Lbs. 
o 


Gauge or 




Disp. 






Disp. 






Disp. 






Vol. 
Eff. 


Min. 


I. H.P. 


Vol. 
Eff. 


Min. 


I.H.P. 


Vol. 
Eff. 


per 

Min. 


I.H.P. 


( 


Cu.ft. 






Cu.ft. 






Cu.ft. 




145 Ibs., 82 F 0.79 


7 


28 


1.65 


0.812 


5-7 


i-4 


0.83 


4 


5 


1.2 


165 Ibs., 89 F 


0-775 


7 


5 


1.83 


0.797 


59 


1.56 


0.815 


4 


6 


i-34 


185 Ibs., 95.5 F.... 


0.76 


7-8 


2.01 


0.782 


6.0 


1.72 


0.80 


4 


8 


1.49 


205 Ibs., 101.4 F. . . 


Q-745 


8 


05 


2.19 


0.767 


6.2 


1.89 


0.785 


c 


o 


1.63 




Suction Pressures and Temperatures of Saturation. 


High Pressure by 
Gauge and Temp, of 


20 Lbs. Gauge or 5.7 F. 


25 Lbs. Gauge or 11.5 F. 


















Vol. Eff. 


Disp. per 
Min. H.P. 


Disp. per 
Vol. Eff. Min. 


H.P. 






Cu.ft. 1 






Cu.ft. 


145 Ibs., 82 F 


0.842 


39 i -06 


O 


855 : 3-4 




0.94 


165 Ibs., 89 F 


0.827 


4-i 


I . 20 


O 


84 


3-5 




1.07 


185 Ibs., 95.5 F.. . . 


0.812 


4-2 


i-34 





825 


3-6 




i . 20 


205 Ibs., 101.4 F. . . 


0.797 


4-3 


i-47 


0.81 


3-7 




1.32 



From the above table it is seen that the range of temper- 
ature has a great effect, the variation in the table being from 
2.19 H.P. per ton to 0.94 H.P. per ton. It is absolutely nec- 
essary to know conditions before a given problem can be 
solved. The smaller the range of temperature, the less the 
H.P. required. The table has been based on tests made 
on compressors with a clearance of not more than -fa" and 
with no after cooling. With after cooling there would be a 
reduction in horse-power. To find the engine horse-power, 
an allowance of 17% must be added for small compressors, 
-and 15% for large compressors to care for friction. 

To utilize the fact that small temperature range means 



THERMODYNAMICS OF REFRIGERATING APPARATUS 107 

an increase of efficiency, Mr. G. T. Voorhees patented the 
application of multiple effect to absorption and compression 
machines, when different temperatures are applicable on the 
lower side of the system. The compressor system and absorber 
system are shown in Fig. 35. In this system the vapor from 
the compressor or rectifier is sent to the condenser and after 
it passes a throttle valve to reduce its pressure to a point above 




Brine Coole 
iHF. 



FIG. 35. Voorhees Multiple Effect Apparatus. 

the lowest pressure used, it is caught in a receiver called by 
Voorhees, a multiple effect receiver. From the receiver some 
of the liquid may pass without throttling to a brine cooler, 
and the evaporation from this passes back into the receiver. 
Some of the liquid from the receiver is passed through another 
throttle valve and is delivered at a lower pressure to another 
brine cooler or refrigerating coil. The low pressure in this 
coil is maintained by a compressor or by an absorber of low 
pressure. In the case shown in the figure, the absolute pres- 



108 ELEMENTS OF REFRIGERATION 

sure is about 15 Ibs. per square inch. The vapor formed in 
the receiver from the evaporation in the first cooler and from 
the throttling of the liquid in the first expansion valve is taken 
to an absorber of 37 Ibs. absolute pressure in one case, or to a 
cavity at the end of the stroke of the compressor, so that when 
the piston overrides a port at the end of the stroke, this vapor 
at 37 Ibs. pressure will flow in, since the pressure inside of the 
compressor at the end of the suction stroke is slightly less 
than 15 Ibs. The ammonia is now compressed and the cycle 
is followed out again. The card from the compressor is seen in 
Fig. 32. In the absorber, the low-pressure absorber receives 
the weak liquor from the interchanger and delivers a stronger 
liquor through the pump to the high-pressure absorber, and 
this delivers its strong liquor to the analyzer through the 
interchanger. 

The purpose of these two inventions is to utilize different 
ranges of temperature where possible, as the efficiency may be 
increased. In cutting down the range for part of the opera- 
tion, this part is done more efficiently and consequently the 
total effect is better. 

There are many cases in which there is some cooling at 
a higher temperature than another, and whenever that is so, 
this method can be used. Thus, to reduce the temperature 
of water to 40, brine at a higher temperature than that required 
to freeze the water could be used. If certain rooms are re- 
frigerated to 35 while others are at 20, this method could be 
employed. One of the latest applications is by the Quincy 
Market Cold Storage Co., of Boston, in their new looo-ton 
compressor, the largest ever built. This compressor draws 
ammonia from two systems, the cold-storage system of low 
pressure and the conduit system at a higher pressure. 



CHAPTER IV 
TYPES OF MACHINES AND APPARATUS 

THE compressor is the important part of refrigerating 
apparatus. Fig. 36 shows a section through the housing of a 
York compressor. The driving of these compressors is accom- 
plished by an engine or electric motor. The former is shown 
in Fig. 14. Fig. 36 shows a section through both cylinders. 
As is true in most large vertical compressors, the two com- 
pressors are connected to a common shaft with cranks at right 
angles. One steam cylinder is usually employed. This is hori- 
zontal and is connected to one of the two crank pins. The 
form of housing is clearly indicated by Figs. 14 and 36. The 
housings must be solid and of proper section to make a rigid 
construction. The box-girder columns are connected at the 
bottom by the casting which carries the main bearing and gives 
a very strong form. The working platforms for large machines 
are carried from the housing or frame. The fly-wheel is placed 
between the cylinders, being supported in a simple manner by 
the two bearings. 

The cylinders are built as shown in the figure. They are 
single acting and are made of close-grain metal. The suction 
enters at the bottom of the cylinder on the up-stroke of the 
piston. The piston is made long and has four piston rings 
to give tightness. The piston casting is carried by a spider and 
hub so that the ammonia may pass through the suction valve 
at the center of it. This valve has a central spindle to which 
is attached a cushion head. This is a plate. A projecting 
cup carried by a spider from the removable seat receives the 
plate. This plate and cup fit so closely that they form a dash 
pot and prevent the hammering of the valve and limit its motion. 
A spring is also used to aid in supporting the valve. 

109 



110 



ELEMENTS OF REFRIGERATION 



The gas is sucked into the upper end on the down-stroke 
of the piston, and when the compressor reverses, the valve is 
closed and the ammonia is compressed until the pressure 




FIG. 36. Cross-section of York Compressor. 

beneath the valve at the center of the head is greater than 
the pressure above. As will be seen, this valve is controlled 
hy a small spring on top of it, but the dash pot into which 
a cylindrical projection on the back of the valve fits, pre- 



TYPES OF MACHINES AND APPARATUS 



111 




FIG. 360. Sectional View of York Compressor. 



112 ELEMENTS OF REFRIGERATION 

vents this spring from slamming the valve down on the 
seat. As is the case with the suction valve, the valve seat 
is removable. The working head of the cylinder is not 
bolted to the cylinder flange, but is held down by heavy 
springs pressing against the outer head, which is bolted fast 
to the cylinder. The joint between the outer head and 
flange is made tight by a lead gasket in a groove on which 
a ring projecting from the head presses. The purpose of 
the inner head is to eliminate the danger resulting from the 
small clearance used in these compressors. The piston is brought 
up so that it practically touches the cylinder head. Any 
incorrect adjustment of connecting rod, or the presence of scale 
would force the piston against the head and break off the 
cylinder were it not for this yielding safety head. 

The stuffing-box is long and contains, in. addition to the 
large amount of packing, a lantern of metal through which oil 
can be forced on the rods. This lantern is composed of two 
rings connected by bars at intervals. A long bushing or gland 
presses against the soft packing. The cap presses this and is 
screwed on the box by means of a gear wheel, the shaft of which 
is led to a convenient point for operation. The lower part of 
the cylinder is a separate casting to simplify construction. 

The thin sheet-metal cylinder covered with wood lagging 
and bolted to a large flange at the lower end of the cylinder 
casting forms a water jacket for the removal of some of the 
heat of compression. It does remove some heat and so reduces 
the work of compression, but the amount is not large. The 
York Company has experimented and found that the jacket 
as originally made is not an element of gain, and for that 
reason their later jackets are placed only at the upper end of 
the vertical cylinder. If heat is removed at all by the jacket 
there should be a gain. It may have been that the lower 
part of the jacket warmed the incoming gas and cut down 
the weight taken in, but as stated above, if the jacket re- 
moves any heat it should be an element of economy. 

All parts of this cylinder and piston are easily accessible. 
This, together with the facts that there is no bottom wear or 



TYPES OF MACHINES AND APPARATUS 113 

friction on the cylinder and stuffing-box, from the piston and rod, 
in the vertical position, and that there is no stuffing-box exposed 
to high pressure, has led to the selection of a vertical single- 
acting compressor. The stuffing-box does not require such tight 
packing and this reduces the friction. In a double-acting com- 
pressor it would be difficult to use safety heads, and so the 
clearance must be greater. Of course this does not increase the 
work of compression except for friction, but it does cut down 
the volumetric efficiency, requiring a slightly larger cylinder. 
The use of two cylinders, whether of double or of single action, 
is advantageous in that if one must be disconnected for repair, 
the other may be operated alone and the plant kept in operation. 




FIG. 37. Indicator Card from Compressor with Guide Lines. 

Fig. 37 shows an indicator card taken from such a com- 
pressor. If the clearance line, absolute zero line, suction-pressure 
line and discharge-pressure line are drawn on this card and then 
the adiabatic is constructed as shown by the method below, 
certain information may be had in regard to the operation 
of the compressor in addition to the knowledge of the power 
taken. The horse-power is worked out in the usual manner. 

If the suction-pressure line is much above the back-pressure 
line, there is excessive valve friction due to the spring being too 
tight or the valve sticking. If the discharge pressure is much 
below the upper pressure of the card, the same may be said of 
the discharge valve. If the adiabatic falls below the compres- 
sion line, there must be a leaky discharge valve, while a com- 
pression line below the adiabatic would mean a leaky suction 



114 ELEMENTS OF REFRIGERATION '_ 

valve or piston. The jacket does remove heat and causes 
the compression line to fall below the adiabatic line in theory, 
but this amount is so small that it can hardly be noticed on the 
card. Hence, when there is a decided drop below the adiabatic,. 
which is what is desired in theory, one must look for a leaky 
piston or suction valve, as the ordinary jacket could not pro- 
duce the result. 

The construction of the adiabatic is one which would have 
to be made by use of an equation of the form 

pv n = const. ... ", . . . . . (i) 
If the compression is dry, the adiabatic is of the form 

/w 1 - 33 = const (2) 

For wet compression the value of n must be computed 
for any given condition. The conditions at the ends of com- 
pression must be known. The quality x at one end is related 
to that at the other by the equation 

, , Xin , . X2T2 

*!+--- =S 2 + (3) 

i 1 -L2 

s' = entropy of the liquid; 
y = entropy of vaporization; 
x = quality. 

In this #1 may be found from x 2 since the two pressures are 
known, or as is usually the case, x 2 is made unity and then 



, x. 
(4) 

1 2 

Having xi and x 2 the volumes per pound may be found by 
vi=xiv"i. ' ". ;'.'.'. . . (5) 

V 2 = X2V" 2 (6) 



TYPES OF MACHINES AND APPARATUS 

i 1 = vol. of i Ib. of mixture ; 
v" =vol. of i Ib. of dry vapor. 

Then n is given by 



115 



n- 



(7) 



After the n for wet compression is found, the equation is 
known. Having the values of n, the volume vi from the zero 
volume line and the pressure pi from the zero pressure line 
are measured in inches and then by assuming other volumes the 
pressures at those points may be found by 



n log Vl 
These are tabulated for n = 1.33 for the card. 



(8) 



Point 


! i 


a 


b 


C i 


Volume in inches 


: 2.16 


I . 20 


' 0.80 


0.70 I 



Pressure in inches . . 



0.24 | 0.53 



0.90 



The motor driving the compressor may be one of various 
types. For large compressors efficient Corliss engines are used 
for refrigeration, although for ice-making where distilled water 
is needed, less efficient engines are used. Gas engines are used 
at times and electric motors are of great value for small plants 
in hotels, hospitals, stores and residences. 

One of the early successful ammonia compressors, used in 
the days of the introduction of mechanical refrigeration, which 
has remained one of the leading compressors, is that built by 
the de La Vergne Machine Company. The cylinder of their 
vertical type is shown in Fig. 38. This is their vertical double- 
acting compressor. The head of the cylinder contains several 



116 



ELEMENTS OF REFRIGERATION 




FIG. 38. De La Vergne Vertical Double-acting Cylinder. 



TYPES OF MACHINES AND APPARATUS 117 

delivery valves placed in a casing. The suction valves are 
placed in casings inserted in the sides of the cylinder. Each 
valve is held to the seat by means of a spring and is arranged 
to be guided by a long sleeve around a central spindle. This 
forms a dash-pot action and prevents slamming. The suction 
valves are in cages forced into radial recesses in the cylinder. 
By removing the cover of the recess, the valves and their seats 
may be removed for examination or repaif since the valve 
cages include valves, seats, springs, and dash pots. The head 
discharge valves are placed in a casing or housing. This is held 
against a projecting part of the cylinder casting making a gas- 
tight joint by the head pressure in addition to the pressure from 
a set screw attached to the main head of the cylinder. This 
set screw has a jamb nut on it and to care for the ammonia 
leakage around the threads, a cap is fastened over the top. 
This cap and the main cylinder head are made gas tight by 
lead-ring gaskets in a groove into which a projecting ring fits. 
These rings and the method of holding the head are made clear 
in the picture. The set screw holding down the valve housing 
is in reality a safety device, for should scale or other obstruction 
fall on top of the piston the bolt would break when the obstruc- 
tion was brought up against the valve housing at the top of the 
stroke. The lower discharge valves are attached to housings 
at the bottom of the cylinder. The stuffing-box gland is shown 
in the figure and owing to the peculiar use of oil in this cylinder 
there is no provision for introducing oil into the gland. 

A peculiar feature of this compressor and that of the de La 
Vergne Company is the introduction of a spray of light paraffine 
oil on each stroke. After spraying this oil forms a thin layer 
over the top of the piston on the down-stroke and one on the 
lower cylinder head on the up-stroke. In this way the piston 
and piston rod are sealed with oil, thus cutting down the tendency 
to leak. This oil also fills up the clearance space at the top end 
of the stroke. The excess oil is driven out through the valves. 
This of course reduces the clearance to zero. At the lower end 
of the stroke the oil would not flow away readily, so valves are 
introduced into the piston allowing oil to enter the hollow part 



118 



ELEMENTS OF REFRIGERATION 




TYPES OF MACHINES AND APPARATUS 119 

of the piston. From this, space the oil discharges through the 
upper discharge valve, when it is connected with this space 
at the lower end of the stroke by an opening in the side of 
the piston. In this way the oil is carried out without the 
danger of breaking the compressor. This injection of liquid 
also absorbs some of the heat of compression and makes the 
work less. 

The piston is fairly deep considering the fact that the 
oil seal cuts down the amount of leakage. This also reduces 
the friction. The piston rod is held to the piston by a circular 
nut and projecting collar. The construction with two parts 
is clearly shown. 

The false cap held on the cylinder head by the tap bolt is 
for finish only. 

The suction and discharge pipes are attached by means of 
flange unions. 

The use of oil requires additional apparatus to recover the 
oil from the discharge. The heated gas is first passed through 
the fore cooler, Fig. 39, and after being cooled it is taken to the 
pressure tank, where the oil separates out and the remaining gas 
goes to the condenser. The oil taken out goes back through 
the strainer to the engine; other oil which enters the condenser 
is finally separated from the liquid ammonia in the separating 
tank. The oil here separates and passes over to the com- 
pressor, being sucked in on the proper stroke. Fresh oil may 
be added to the system by the oil pump when needed. 

The liquid ammonia is taken from the storage and separating 
tanks by the main liquid line to the various expansion coils in 
rooms or brine tank. The suction is brought back to the main 
suction pipe of the compressor. 

Fig. 40 illustrates a horizontal type of compressor brought 
out by this company. The suction valve A opens into the 
passage B, which is connected to the cylinder C. The suction 
valve with its seat, spring and dash pot are in a housing which 
is held in place by a bonnet or cover-plate. The discharge 
valve D is in a similar housing. Either of the valves may be 
examined by simply removing the head. The housings are 



TYPES OF MACHINES AND APPARATUS 121 

arranged with slots so that gas from the suction main E enters 
the space F and goes through the valve from this into the 
cylinder. In the same way the discharge from the valve D 
passes through G into the discharge main H. In this cylinder 
there is no chance for the valves falling into the cylinder and 
any scale or obstruction would tend to fall into the space at 
the lowest point of the cylinder barrel. The piston and its 
attachment to the rod are clearly shown. The double-lanterned 
stuffing-box is shown. This is due to the fact that there is 
no oil lying around the rod as in the former case. The lubrica- 
ting oil enters at 7 and is taken out at /. At K in certain cases, 
a connection is made to the suction pipe to remove any ammonia 
which has leaked past the first set of packing rings. 

The cylinder is surrounded by the jacket M. 

The cylinder of a horizontal double-acting compressor of 
the Frick Co. is shown in Fig. 41. This company builds ver- 
tical compressors which are very similar in general features to 
the compressor of the York Manufacturing Co., so that no section 
of that type will be shown. Tha cylinder is provided with 
valves in the spherical heads arranged in radial lines. They 
are arranged in this manner to increase the valve area for a 
given diameter of cylinder while using a small amount of clear- 
ance. There are usually two suction valves and two discharge 
valves on each end. The two upper valve boxes are con- 
nected, as are the two lower discharge boxes. As shown 
in "the figure, these valves are so arranged that the seats, 
springs and valves may be removed with the valve housings 
by simply removing the bonnets. The long stuffing-box, the 
wide piston, the packing ring for the lead gasket in the heads 
and bonnets, the water jacket and the other peculiar features 
of ammonia compressors are clearly seen. The piston rod is 
properly attached by a nut. Some builders attach the rod by 
peening over the end after forcing the rod on the piston. This 
is not good practice and should not be resorted to unless ab- 
solutely necessary. It is better to use some form of nut or 
cotter pin. The piston is made in two parts, making a simple 
core arrangement in casting. To stiffen the cylinder, long 



TYPES OF MACHINES AND APPARATUS 



123 



through bolts are passed from one end to the other, thus relieving 
the cylinder of strain. The stuffing-box is provided for an oil- 
supply attachment, and an ammonia pipe returns to the suction 
pipe gases which leak out; these features are shown by dotted 
circles at the center of the rods. 

For the proper operation of compressors it is necessary at 
times to remove the vapor from the cylinder. To do this there 




FIG. 42. Frick Manipulating Valves for Small Compressors. 

are certain by-pass arrangements common to most compressors. 
The arrangements used by the Frick Company are shown in 
Figs. 42 and 43. To exhaust the vapor from one compressor 
the machine is shut down and all of the valves are closed. The 
purge valve 10 is opened. This permits gas to escape. The 
machine is now operated slowly. The cylinder head of L may 
be removed. To exhaust R, the same method is used. 

To exhaust the condenser and store the ammonia in the 
expansion coils, close all- valves after shutting down, then open 



124 



ELEMENTS OF REFRIGERATION 



the valves i, 2, 3, 4 and 12 and start the machine slowly. The 
gas for compressors is sucked through valves i, 12 and 2 from 
the discharge main, while after compression it is discharged 
through 3 and 4 into the suction piping. 

To admit air into the high side for testing, close the suction 
valves 5 and 6, and leave the discharge valves 7 and 8 open. 
Open valves i and 2, removing the plug from tee n. Valves 
3, 4 and 12 are closed. Air is then drawn in by i and 2, when 
the compressor is driven slowly. 

To admit air for testing low side, the suction valves 5 and 6 
and the discharge valves 7 and 8 are closed. Valves i, 2, 3, 4 




FIG. 43. Frick Manipulating Valves for Large Compressors. 

are opened and the plug in tee 1 1 is removed. Air will enter i 
and 2 when the compressor is run slowly and the discharge is 
passed into the suction main by 3 and 4. 

Before air is introduced on either side the ammonia is ex- 
hausted from that side by pumping the ammonia into the other 
until a low vacuum exists on the side from which the vapor is 
being pumped. 

For larger compressors a different arrangement of pipes is 
used, as shown in Fig. 43. In this case, valves i and 2 are 
attached to valves 5 and 6 and then valves 9 and 10 are added 
to the pipes running from 4 to i and from 3 to 2, while valve 
ii connects to the suction pipe. 



TYPES OF MACHINES AND APPARATUS 



125 



To exhaust the compressor R, all valves are closed after 
shutting down the compressor. Then stop valve 8 is opened 
with 2 and 3. The valve 10 when closed prevents any con- 
nection to the suction at that point. If the compressor is 
started slowly, the compressor L draws from R and frees it of 
ammonia. Valve 2 opens inside of 6. 

To exhaust the condenser the valves opened are 8, i, 4, 3, 
10 and n. In this case the gas is sucked from the discharge 
pipe through 8, 4, and i into R and then the compressor vapor 
passes over through 3, 10 and n into the suction mains. The 







FIG. 44. Section of Arctic Horizontal Double Single-acting Compressor. 

other compressor could have been used. To empty the suction 
the compressor is operated in the usual way with the reducing 
pressure valve closed. 

One recent improvement in the arrangement of compressors 
is that of the Arctic Machine Co. in their center inlet horizontal 
double-acting compressor shown in Figs. 44 and 45. In this 
compressor the inlet valves in the piston are similar to the 
hurricane inlet valves of the Ingersoll-Rand air compressors. 
To avoid the piston-rod inlet connection, the two piston faces 
are separated a distance equal to the stroke of the compressor 
and the center of the piston barrel is cast with openings leading 



126 



ELEMENTS OF REFRIGERATION 



from a ring passage into the cylinder bore. The suction vapor 
enters this passage and the space between the two piston faces. 
There are a series of openings extending through the piston 
face near the periphery and these are covered by a ring of 
metal. When the piston starts from one end, a vacuum 
forms behind the piston, and the gas between the piston faces, 
being at a higher pressure, forces the ring out against a stop 
and enters behind the piston with little change in pressure. 
At the other end of the stroke, the acceleration of the recipro- 
cating parts when the piston begins the return stroke closes 
this valve and the piston begins to compress. In this way 



m 



Valve Closed 
FIG. 45. Suction Valves and Pistons of Arctic Compressor. 

the compressor acts rapidly on the suction stroke with little 
drop in pressure. 

The discharge valves and housing are connected to the 
lowest part of the cylinder at each end, thus caring for scale 
and liquid. These valves may be examined by removing the 
bonnet. The springs and dash pot are seen in the figure. 

The cold ammonia coming to the center does not affect the 
stuffing-boxes and the jackets are removed from the cold parts 
of the cylinder. An insulating filling is placed at the center to 
cut down radiation. The heads are jacketed as well as the barrel 
ends. The path of the water is seen. 

The stuffing-box is shown with its oil connections. There 
is also a connection leading from the stuffing-box to the suction 
main. 

The piston detail is shown in Fig. 45. The valve disc is 





TYPES OF MACHINES AND APPARATUS 



127 



the ring A , the motion of which^ is limited by the guard ring 
or projection B. The openings C are distributed around the 
periphery of the piston. The method of attaching the piston 
is proper in this case "as the load is taken by a shoulder. 
Each of the piston faces is in reality a single-acting compressor. 
The action of the suction valve is so free that, according to 
reports on the compressor, the suction drop was only i Ib. at 
300 R.P.M. 

The valves of the compressor of the Triumph Ice Machine 




FIG. 46. Valves of the Triumph Ice Machine Co. Compressor. 



Co. are shown in Fig. 46. These valves and their seats are 
held in a housing or cage which is held in place by a nut screwed 
into the valve cavity and containing set screws to hold the cage 
tight against the head casting. The suction valve spindle is 
held up by two springs each with a separate adjusting collar. 
These collars may be held tight by jamb nuts or set screws. 
The small collar at the lower end of the suction spindle acts 
as a dash pot. 

In the discharge valve there are two springs holding the 
valve down and a cup acting on a shoulder or collar on the 



128 



ELEMENTS OF REFRIGERATION 




TYPES OF MACHINES AND APPARATUS 129 

spindle serves as a piston and dash pot. In each case the 
long spindle guide keeps the valves in line. 

The cylinder of a carbonic acid machine will be shown 
because of the special features due to the high pressures carried. 
One of the best known compressors of this type is that of 
Kroeschell & Co. and is shown in Fig. 47. The cylinder is a 
rectangular steel forging in which the ports are drilled from one 
end. The various valves are placed in housings which are held 
in place by bonnets. These valves are operated by springs 
as shown. The suction valves have helical springs while a cap 
on the top of the spindle limits its movement. The discharge 
valves have a spring to support them and a flat spiral spring 
to force them back. The seats are held in by bonnets or cages 
and may be removed readily. The bonnets are made tight by 
fiber washers. 

The piston is packed with cup leathers to sustain the high 
pressure. One end is flat because of the head and the other end 
is spherical in order to place the two suction valves and one 
discharge valve. 

The piston rod is packed with a series of cup leathers with 
provision for circulating oil. 

The two suction passages are connected around the head 
valve, the suction pipe entering one of the passages at the center 
as shown. The discharge passage is connected to the top face 
of the cylinder. Each of these is controlled by a valVe. The 
valves, Fig. 47, have drips or scale chambers at the bottom to 
catch dirt. The discharge passage is connected to an open- 
ing covered by a thin plate which will break when excessive 
pressure is brought on the discharge by shutting off the 
discharge stop valve [or by a stoppage of the system. A 
relief valve is also fixed on the suction side to relieve excess 
pressure. 

The parts of this compressor are made of steel, due to the 
heavy pressures. The remaining part of the compressor is 
similar to any other type. 

Fig. 48 shows one of the Kroeschell marine compressors in 
which the double-pipe brine cooler and double-pipe condenser 



130 



ELEMENTS OF REFRIGERATION 




TYPES OF MACHINES AND APPARATUS 131 

are placed in the base of steel. The steam engine driving this 
is seen at one side of the compressor. 

One of the latest types of machines in which the compressor, 
condenser, brine cooler, and pipe system are contained within 
the same casing is shown in Figs. 49 and 50. This is the 
Audiffren-Singrun Refrigerating Machine, as sold by the H. W. 
Johns-Manville Co. In the spherical case A is a hollow shaft 
J3, supporting as an axis a casting V which is so heavily weighted 
by W that it will not turn. This casting carries the trunnions 
TT of a cylinder C, the piston of which is connected to a rod 
attached to the strap of an eccentric sleeve D on the shaft. 
If the whole casing is turned and with it the shaft, the heavy 
weight remains down and the piston in the cylinder is drawn 
in and out by the eccentric while the cylinder oscillates. Thus 
oscillation of the cylinder between the faces of the suspended 
casting causes the face of the cylinder casting to oscillate over 
the face of the right-hand casting which contains holes. In this 
way the ports of the two ends of the cylinder are connected to 
suction ports N in the hanging casting at the proper time in the 
same way as the distribution of steam is accomplished in the 
oscillating engine. In this way 862 vapor is admitted to th e 
cylinder from the annular space E between the two shafts and the 
space F when the holes at G in the cylinder and face come oppo- 
site. The vapor is compressed in the cylinder and when the 
proper pressure is reached the discharge valves at H open and dis- 
charge the vapor into the casing A . The casing revolves in a tank 
7, Fig. 50, containing the cooling water. This condenses the 
sulphur dioxide and the liquid collects at the outer part of the 
casing A , and is caught up by a scoop M, and is conducted to the 
reservoir /. It is then delivered to a regulating float throttle 
valve after the lubricating oil is removed from the SCV The 
oil flows over at U into the chamber in which the cylinder 
is placed. Thus the eccentric and cylinder are flooded with 
oil. This whole region is under pressure, so that there is no 
leakage from the compressor. There is a tendency for the oil 
to enter around the piston rod and between the valve faces- 
The spring X holds the system against the sliding face. The 



132 



ELEMENTS OF REFRIGERATION 




TYPES OF MACHINES AND APPARATUS 



133 



liquid S02 at low pressure after passing the throttle valve travels 
along the inner pipe extending between the two vessels and finally 
settles to the circumference of the other spherical vessel, due to 
centrifugal force, and it is evaporated as it removes heat from 
the brine in the tank R, Fig. 50. The vapor is returned through 
a space formed between the two pipes between A and Q, and 
passes into the 862 compressor. The complete system is con- 
tained within a tight set of vessels and pipes, and there are no 
moving joints to be kept tight. There is no danger of 
leakage. An extension on the right-hand vessel serves as 
one journal for the system and the intermediate pipe serves 



Refrigerated Box 



FIG. 50. Audiffren Singrun Apparatus. 

as the other. There is little weight on the journals, as the 
buoyancy from the immersed vessels supports much of the 
weight. The gas pressure in A tends to hold the oscillating 
piston against its face in addition to the spring pressure, 
and keeps the sliding joint tight. Should the condensing 
water be shut off and the temperature rise, the high pressure 
developed would finally be sufficient to cause the weight to 
rotate and so prevent a further rise in pressure. The small 
valve at 5" is held down, when the apparatus is in opera- 
tion, by centrifugal force, but upon stopping the machine this 
valve is opened by the weight of the balls, thus equalizing 
the pressure. The following table gives the data for these 
machines: 



134 



ELEMENTS OF REFRIGERATION 



Size of 
Machine. 


Capacity in Tons. 


Power Required. 


R.P.M. 








Refrigeration. 


Ice. 




2 


0.19 


0.13 o.4too.6H.P. 


380 


3 


0.48 


0.32 i to i . <5 


280 


4 


0.96 


0.66 


2 to 2^25 


190 


6 


1.92 


1.32 


4 to 4 . 50 


140 



The great advantage of such a machine lies in the fact that 
there is no manipulation of valves, stuffing-boxes, gauges or 
oiling devices. 

In Fig. 50 the general arrangement of this apparatus is seen. 
The cooling water in / liquefies the 862, while the evaporation 
of the 862 cools the brine in the tank R. If this brine is cooled 
completely there will be no evaporation of SC>2, and there will 
be no gas sent back to the compressor, and consequently none 
will be liquefied in the case in A . Hence, after a short time the 
level of the liquid in / will be such that the float valve K will 
be closed off and no more liquid 862 can pass over to R. The 
motor is attached to the pulley Z. 

The above gives the necessary details of the compression 
machines. The parts of the absorption machine will now be 
considered. 

Generators. In Fig. 19 a cross-section through a generator 
is shown. This is seen to be made of a circular tank with 
flanged ends and dished heads, containing several coils of steam 
pipes connected to manifolds. This is of cast iron, and bolted 
to a T-connection is the analyzer, containing a series of trays 
over which the liquor from the exchanger and rectifier flows. 
The pipes are so arranged that the gases have to pass through 
the liquid. The cast head, dished to give strength, is shown. 

In Fig. 51, the generator of the Henry Vogt Company is 
shown. In this strong liquor flows into the top section of the 
generator from the exchanger. The excess liquor flows from this 
at the left-hand end to the next section, and the excess from 
this might flow into a lower section if used. In this way the 
liquor travels the whole length of the section before leaving it. 



TYPES OF MACHINES AND APPARATUS 



135 



The weak liquor is taken off at the right-hand end of the 
lower section. The connections are made to give a definite 
liquid -level in each section. The vapor formed in each section 
is taken up through a main pipe to the rectifier. The steam 
coils are connected to manifolds which are connected together 




FIG. 51. Vogt Double Cylinder Generator. 




FIG. 52. Vogt Modern Generator. 

on the steam side and at the discharger end. The cylinders 
and heads are made of cast iron and the supports are made to 
carry these from the lower sections. 

The analyzer is arranged at times to cause the vapors to 
travel up through the strong liquor which flows over per^ 
forated plates. The gas is then carried to the rectifier. 

Fig. 52 is a section of one of the later forms of Vogt gen- 



136 



ELEMENTS OF REFRIGERATION 



erator. The generator is made of semi steel pipe with dished 
heads using a tongue and groove packing. The strong liquor 
pipe passes through a stuffing box and is attached to the 
analyzer header A. From this point the liquor is carried into 
a number of tubes forming the analyzer in this case. These 
are in the space through which the heated gases pass on the 
way to the outlet and dry pipe B. 

The weak liquor is taken from C and at DD the glass gauge 
gives the level of the liquor. The evaporation occurs at the 
surface of the closed steam pipes, E, which are screwed into 
the head. The manifold cap has a series of small tubes, G y 




Vqpor 



FIG. 53. Vogt Rectifier. 



attached to it, and taking steam from F to the ends of the 
closed tubes. Then the condensed steam is removed at the 
lower part of the head. 

This construction is quite simple and effective. 

Rectifier. The rectifier is made in several ways. In some 
cases, as in Fig. 19, it consists of a coil of pipe made up of return 
bends, through which the vapors flow to the separator and con- 
denser while cooling water is passed over it. In other cases it 
is formed as a double-pipe condenser, the construction of which 
will be explained later. When this double-pipe apparatus is 
used, Vogt uses the strong liquor as cooling substance, passing 
it directly to the rectifier before it enters the exchanger. 



TYPES OF MACHINES AND APPARATUS 



137 



Exchanger. The exchangers are of various forms. In Fig. 
19 the form is a cast-iron cylinder with a coil within. This 
coil carries the weak liquor and while the strong liquor passes 
around this coil as it goes through the shell. The York Com- 
pany and Vogt use a double pipe construction for this apparatus. 

Weak Liquor Cooler. This is of double-pipe construction. 

Absorber. The absorber is made in several forms. In all of 
them vapor enters at bottom and is distributed through a per- 
forated pipe. The weak liquor is distributed near the top of 
the absorber, the flow of weak liquor being controlled by a 




FIG. 54. Vogt Absorber. 

float shown in Fig. 55. This float is attached to the side of the 
a sorber. The action of the float is to control the admission of 
weak liquor by the valve A. The strong liquor is pumped 
from the bottom of the vessel, which is usually made cylindrical. 
In the absorber there are sets of tubes carrying cold water to 
remove the heat of absorption. 

Fig. 19 gives the construction used by the Carbondale Co., 
while Fig. 54 is the absorber of Henry Vogt & Co. The drawing 
shows the construction and the manner in which there are four 
passes of the water. 

The other parts of the apparatus being used with this and 
compression machines will now be described. 



138 



ELEMENTS OF REFRIGERATION 



Piping. The piping for ammonia should be full weight or 
extra heavy wrought-iron pipe. The pipe is united with 




FiG. 55. Vogt Regulator for Weak Liquor Inlet. 

screwed fittings, flanged fittings and by welding. For use with 
-CO2 extra heavy pipe must be used. This is determined by 
the pressure to be carried and the opinion of the engineer. 



TYPES OF MACHINES AND APPARATUS 



139' 



Ammonia pressures will run as high as 200 Ibs. per sq.in., while 
carbon dioxide may be 1000 to 1200 Ibs. The best method of 
uniting these pipes is by welding, as there is no chance for 
leakage, although they cannot be dismantled easily. Weld- 
ing is done by the use of thermit, the oxy-acetylene torch or by 
electricity. In this work the parts are clamped together tightly 
and thermit is ignited in a crucible, after which the aluminum 
oxide and the hot iron are poured into a mold around the pipe 
and produce a welding temperature. Thermit is a mixture of 
Fe2Os and 2A1. It burns to 2Fe and A^Os, producing a tem- 
perature so high that the molten iron and slag can heat the 
pipe to a proper point for welding. The thermit powder is held 




FIG. 56. Thermit Pipe Welding. 

in a crucible and after ignition is complete it is poured into 
the mold around the part to be welded. 

Before welding the pipe ends are milled smooth by a special 
facing machine and are then clamped and held tightly together. 
An iron mold is then put around the pipe and the thermit 
poured in as shown in Fig. 56. When the operator feels the 
clamp, Fig. 57, yield he knows that the iron has reached a weld- 
ing heat, and by pulling the clamps together and giving four 
quarter turns of the bolt the weld is made. After the weld is 
made the mold should be left ten or fifteen minutes if possible, 
and then removed. The iron and slag will fall away. Thermit 
is placed in bags with the proper amount for a given size pipe. 
In igniting it, it is customary to use about one-half of the package 
at first and then, after igniting it by means of an ignition powder 
and match, the remainder of the package is poured in. The 



140 ELEMENTS OF REFRIGERATION 

slag first forms a coating around the pipe, protecting it from 
the molten iron. The heat is used only to bring the iron to 
a welding temperature. 

Tests of pipes welded in this manner have shown that the 
weld is as good as the pipe in tension, torsion and bending tests. 
The cost of thermit welding amounts to 75% of the cost of 
elbows or flanged joints for small sizes, while for four-inch flanged 
joints the thermit cost is greater than the cost of fittings. 

The use of the oxy-acetylene torch is valuable in cutting 
as well as in welding. C2H 2 is mixed with 62 in the nozzle, 
and if just enough oxygen is introduced, the flame will consist 
of CO2 and H2O. The heat is produced by the breaking down 
of the C2H2 and by the formation of CO2 and H^O. An 




FIG. 57. Thermit Welding Clamp and Mold. 

intense flame temperature is obtained. When welding is de- 
sired the mixture is as given above, and by pressing the parts 
together and melting a stick of steel by the flame to flow into 
the interstices a fixed weld is made. If it is desired to cut the 
metal, a correct burning mixture is used on the outer part of 
the flame and after this heats the metal, a flame rich in oxygen 
is thrown out from the center of the nozzle and burns a groove 
through the metal. This torch is particularly valuable for 
welding plate work. The temperature is so high that the H^O 
is dissociated and the hydrogen burns on the outside of the 
flame. 

In electric welding an alternating current of low voltage 
but great current strength is delivered from a transformer 
through large leads clamped to the pipes to be welded. The 



TYPES OF MACHINES AND APPARATUS 141 




142 ELEMENTS OF REFRIGERATION 

resistance at the butted ends to be welded soon causes these to 
become white hot and the metal is welded. 

The fittings on pipes are usually screwed on. 
thread is~carefully cut and the joint made tight by a mixture 
of litharge and glycerine. This forms a cement and makes a 
good joint if the fittings are made tight. At times, with black 
iron, the threads are tinned over, when the solder makes a 
joint if they are screwed together when hot. This method 
should not be used with galvanized pipe. There are claims for 
each method. 

The flanged unions, Fig. 58, are used for uniting sections 




FIG. 59. Boyle Union. 

which may have to be separated. They are screwed to the pipe 
as shown in the figure or sometimes the type shown at C is 
used. B shows the flange joint of the de La Vergne Co. It 
has a cavity left at the upper end of the screwed portion of the 
flange into which solder may be left as it is forced out from 
the tinned threads when the flange and pipe are heated and 
forced together. This fills the space and threads at one end 
with solder so as to make a solid gas-tight joint. The flanges 
are made of a close-grained malleable iron combining strength 
and toughness, or else drop forgings or steel castings are 
employed. 

The joint between the two flanges is made tight by a lead 
gasket which fits in a groove in one flange and is pressed, down 



TYPES OF MACHINES AND APPARATUS 



143 



by a projecting ring on the other flange. At times lead gaskets 
are placed between flanges as shown in A and C. Fig. 59 







FIG. 60. Elbows. 

illustrates a Boyle union used in refrigerating work. In this 
a change of alignment is possible by properly finishing the ends 
of the nipple. 

Where elbows are needed they 
may be screwed as shown in Fig. 
60 B, and sometimes it may be 
necessary to use a flanged elbow, 
the flange being on one outlet as 
in the figure. Very often both ends 
of the elbow have flanges. A tee, 
Fig. 6 1, is used when it is desired 
to take off a side branch. Return bends are made as shown 



FIG. 61 Tee. 



144 



ELEMENTS OF REFRIGERATION 




TYPES OF MACHINES AND APPARATUS 



145 



in Fig. 62. These tees and bends show different arrangements 
used in ammonia work. Thus one bend B has an extra flanged 
outlet on it. It is a special return bend used on the de La 
Vergne condensers to carry off condensed ammonia. If it is 
desired to connect two sections of a coil, two flange fittings 





FIG. 63. Flanged Return Bend. 




FIG. 64. Branch Tee or Manifold. 

known as return bend flanges are employed. This is shown 
in Fig. 63. 

Manifolds, or headers, for the connections of a number of 
branches, are made by welding. They may take a number of 
special forms, depending on the peculiarity of design. Fig. 64 
illustrates one with fifteen branches for the connection of the 



aafi [-..ELEMENTS OF REFRIGERATION 

different coils 6f a condenser. A cross, Fig. 65, is used at times 
when two lines are to intersect or three branches are to be taken 
from a line. 

:' ; AH of the fittings are extra heavy to allow for the high 
pressures, and after erection the whole system is filled with 
air under pressure. After closing the valves of the compressor 
the system should hold its pressure for hours. Leaks may be 
found by coating jover the pipes and fittings with soapy water. 
In the shop welded joints are tested by immersing the apparatus 
in a tank of water after charging it with air under pressure. 
Since the compression heats the air and the oil vapor from 




FIG. 65. Cross. 

the pipe work might form an explosive mixture which would 
ignite at the temperature due to compression, Block advises 
stopping the compressor for a while after reaching 50, 100, 
150, 200, and 250 Ibs., giving the air some time to cool. 

The pipe hangers for this work must be strong and well 
supported, as many pipes, are filled with brine and loaded on the 
outside with ice and snow. The weight of these must be added 
to the weight of pipe in figuring the strength of the hangers. 
Fig. 66 illustrates several methods of supporting the pipe. 

The valves used as stop valves on the vapor line are of various 
forms with strong flanges and stuffing-boxes. Usually the seat 
has a soft lead ring for giving a tight joint, and the stuffing-box 
is long. The bonnet of the valve is bolted on the main body, 



TYPES OF MACHINES AND APPARATUS 



147 






148 



ELEMENTS OF REFRIGERATION 




TYPES OF MACHINES AND APPARATUS 



149 



using a lead gasket. Two valves are shown in Fig. 67 and each 
of them is provided with flange connections. For angle con- 
nections, valves are built in this form, using an angle body. 
Where liquid ammonia or vapor is to be prevented from return- 
ing, check valves are used. These are made as shown in Fig. 
68, of a lift type known as the cup pattern, due to the guide 
cylinder on the back, or they may be of the swing pattern. 
The massive construction is shown here. For expansion valves 
a small opening which may easily be adjusted for small changes 
is used. This means a needle valve and hence the forms shown 
in Fig. 69 are employed. In each of these the needle valve is 



rm 




FIG. 68. Check Valve. 

raised by a fine-pitch thread so as to give close regulation on 
the amount of liquid discharged. Safety stop valves are built 
for the discharge valves of compressors. These valves are pro- 
vided with a spring-closed by-pass valve which only opens when 
the pressure reaches a high value. 

Condensers. The ammonia condensers are of various forms, 
depending on the plant, its location and size. An open-air 
surface condenser should be used when the cooling water carries 
scale-forming salts which would be deposited at 100 F. This 
condenser may be of several forms. If welded into a continuous 
coil there would be a difficulty in renewing a part of it. Fig. 70 
shows the welded form of Kroeschell & Co. for C0 2 . Welded 
coils are rarely used as condensers. This form is very often 



150 ELEMENTS OF REFRIGERATION 

used as an expansion coil. In Fig. 71, a condenser fitted with 
flange joints between the return bends and pipes is shown, 
while in Fig. 72 screwed joints are used. In Fig. 71 the 




hot ammonia vapor passes through two lower pipes and then 
is taken to the top pipe in contact with the coolest water. 
This water is distributed from the perforated or split pipe 
at. the top of the rack of tubes. In this arrangement there 



TYPES OF MACHINES AND APPARATUS 



isf- 




152 ELEMENTS OF REFRIGERATION 

is a slight counter-current effect, but the main condenser is of 
parallel flow. In Fig. 72 the same general arrangement has 
been used with a change. After the liquid is formed in the 
condenser, it is passed through a small pipe contained in a larger 
pipe, and through the annular space formed between the two 
pipes the coldest condensing water is passed on its way to the 
sprinkling pipe. In this way the liquid is cooled to almost the 
lowest temperature of the cooling water. The condenser shown 
in Fig. 73 is one in which vapor enters at A , which is cooled by 



Water Enters 



Purge Valve 




FIG. 71. Ammonia Condenser with Flange Joints. 

the warmest liquid, and any condensation which occurs is taken 
off at B, C and D, and is passed to the storage tank. Other 
liquid is taken off at E. The cooling water enters at F and flows 
over the slot in the top of the distributing pipe and falls over the 
pipes. At times plates are placed between successive pipes so 
that water will follow from pipe to plate to pipe and will not 
be blown off by a light wind. Flanged joints between elbows 
forming together a return bend permit an easy method of con- 
struction. The drips at certain return bends are cast in the 
bend. The connections between the pipes and fittings are 
screwed joints. 



TYPES OF MACHINES AND APPARATUS 



153 




154 



ELEMENTS OF REFRIGERATION 



Of course, all of these condensers, known as atmospheric 
condensers, have the water sprinkled over the surface so that 
when the' wind blows the water may be blown away from the 
pipe surface and the condensers are therefore placed in shallow 
tanks so that the water may be caught. It is quite customary 
to shield them from the direct action of the wind by the use of 




~il IT ir 

FIG. 73. Sectional Diagram of De La Vergne Condenser. 

slatted blinds. By inclining these properly the water striking 
them will be sent back to the tank. 

The condensers utilize the cooling action of cool air blowing 
against them and hence in cold weather the supply of water 
is decreased. 

In small plants or in places where there would be trouble 
from the falling water, a submerged condenser, Fig. 74, is used. 
In this the vapor is admitted at the top and flows downward. 
Cooling water enters at the bottom of the tank and flows to the 



TYPES OF MACHINES AND APPARATUS 155 

sewer from the top. A drain placed at the bottom will remove 
all water when necessary to break off the scale. This is of the 
counter-flow type. 

One of the best forms of condenser in which the use of free- 




Liquid Outlet 

FIG. 74. Frick Submerged Ammonia Condenser. 

falling water is inadvisable and also where there is little danger 
of scale forming, is the double-pipe condenser, Fig. 75. In this 
one pipe is placed inside of another one, heavy fittings being 
used to connect the ends so that cooling water may be passed 
through the inner pipe while ammonia is condensed in the 
annular space between the two pipes, thus using the air as a 



156 



ELEMENTS OF REFRIGERATION 



heat-absorbing medium as well as the water. The ammonia 
vapor enters at the top at A. The inner pipe passes through 
this special casting having a lead packing-ring stuffing-box. 
From the end B the warmest cooling water leaves. The am- 
monia passes through the annular space between the two pipes. 
At the end C, the water pipes are connected by the return 
bend, while the special casting supporting the two successive 
sets of pipes are connected and the ammonia passes to the 
next level and at the other end this run is connected to the 
next lower. The ammonia and water pipes are connected in 
this way until D is reached, from which the liquid ammonia 




FIG. 75. Frick Double Pipe Condenser. 

passes out. The cold water enters at E. The special return- 
bend castings are arranged so that the water pipe is held in 
place by a stuffing-box and by means of a properly packed joint 
a projection of one box fits into a groove of a lower one and thus 
connects the ammonia channel of two successive lines. The 
bends are held together by bolts. By using the flanges ori the 
outside pipe and the special casting F, any pipe can be 
removed with little work. 

In this double-pipe condenser the velocity of water may be 
increased to a high value, thus increasing the value of the 
coefficient of heat transfer K. This is one of the important 
features of the double-pipe condenser. Its main use has been, 



TYPES OF MACHINES AND APPARATUS 



157 



however, to remove the free water from the installation which 
results in dampness. This is also advisable when the water is 
to be used for other purposes, because the water, which is under 
pressure, may be delivered to any point after warning. 

Fig. 76 shows the method of forming double-pipe condensers, 
as recently suggested by the Philadelphia Pipe-Bending Co. In 




FIG. 76. Philadelphia Pipe Bending Co. Double Pipe Condenser. 

these condensers a tight joint is made by packing being forced 
against the pipe by pressure. 

The latest improvement in condensers is to have a liquid 
coating on the ammonia side of the pipe, as it has been the 
experience of those familiar with this apparatus that if the pipes 
are covered with liquid ammonia they will transmit more heat 
per degree difference per hour per square foot than they will if 
not wetted. The York Manufacturing Company obtains this 
wet condition by injecting a certain amount of condensed liquid 
from the condenser back with the compressed vapor on its way 
to the condenser, using an injector nozzle to take up the liquid 



158 



ELEMENTS OF REFRIGERATION 



and introduce it into the condenser with the vapor. Block 
accomplishes the same thing by casting a ridge in the return 
bends of his condenser, forming a dam which retains a certain 
amount of liquid in each pipe. In this way increased duty from 
a given amount of surface is made possible by the presence 



Block Type 





Shipley Type 
FIG. 77 Block and Shipley Condensers. 

. of liquid inside. This liquid is carried along by the vapor 
flow, i.i; '.-' 

The condenser pipes are supported by vertical pipe supports 
shown in Fig. 78. The pipes are either held between the sup- 
ports or on brackets projecting from the side. Bolts are used 
as the supporting element in the right-hand type, while in the 



TYPES OF MACHINES AND APPARATUS 



159 



middle form the pipes are held by the castings when they are 
held together by bolts. 

Separators. The separators used in the ammonia systems 
for scale or oil separation should be of the same form as those 
used in engine work, but with heavy walls and flanges and a 
strong gasket packing. Fig. 79 illustrates the Triumph Ice 
Machine Co. oil separator. The incoming vapor and oil are 




FIG. 78. Condenser Pipe Supports. 

discharged by means of a cone against the side walls of the 
separator and the oil will cling to the wall while the vapor rises 
slowly through the large cross-section of the cylinder and passes 
a strainer A and leaves at the outlet B. The oil and water may 
be drawn off at the drain valve. 

Liquid Receiver. Liquid receivers are usually made of 
pieces of extra "heavy wrought-iron pipe with flanged heads 
welded in. They are strong and durable. These are usually 
tested to 500 Ibs. air pressure. The outlet from these is con- 



160 ELEMENTS OF REFRIGERATION 

nected to the bottom, the inlet being at the top. In some cases 
the discharge from the condenser enters at the outlet pipe, and 
if there is more liquid coming from the condenser than that 
required by the expander, the liquid can collect, since the two 
valves are connected by an equalizing pipe. 




FIG. 79. Triumph Oil Separator. 

Brine Cooler. The brine cooler is an apparatus in which 
heat is abstracted from the brine by the evaporation of the 
ammonia. Usually the liquid ammonia is admitted at the 
bottom of a coil of pipe and the vapor resulting from the evap- 
oration is taken off from the top. Around this coil the brine 
is circulated, or in some cases the brine is in the coil while the 
ammonia is on the outside. In Fig. 19, the brine cooler is 



TYPES OF MACHINES AND APPARATUS 



161 



equipped with a brine coil, the liquid ammonia being carried 
about one-third of the height of the chamber of the cooler. It 
is always well to have the liquid ammonia in contact with the 
metal of the coil. It would probably yield a larger heat trans- 
fer in Fig. 19 if the liquid ammonia were sprayed over the 
brine coil from the top of the chamber. After the vapor is 
formed there can be little if any further heat removed, so that 
all surface in contact with vapor alone is of little value. 




FIG. 80. Liquid Receiver. 

In the Vogt brine cooler, Fig. 81, the brine is passed through 
the horizontal tubes running between the two head plates in 
a four-pass course, while the liquid ammonia is introduced at 
the center of the shell. In this there is ample heat transfer and 
the surface is efficient. 

Fig. 76 would represent a double-pipe brine cooler as well 
as a condenser if the liquid ammonia were placed on the inside 
of the coil and the brine were on the outside. 

Fig. 82 illustrates a triple-pipe brine cooler. In this, liquid 
ammonia enters the annular space between the two inner tubes 



162 



ELEMENTS OF REFRIGERATION 



of a set of three consecutive tubes at A . This space of one line 
is connected to the space on the next level by the special return 
bend B in the same manner as was used in the double-pipe con- 
denser. This is then repeated at alternate ends until the outlet 
C is reached. At this point is the suction pipe leading to the 
compressor. The brine enters at D and passes through the special 
casting into the outer annular space and then by similar castings 
at E it enters the second row, finally reaching F, at which point 
it is connected to a return bend and enters the center of the 
middle tube. Finally, by pipes and return bend it reaches the 

i Outlet for NH 3 Vapor' 




FIG. 8 1. Vogt Shell Brine Cooler. 

point of outlet G. Of course this appears to be partly counter 
current and partly parallel flow, but it must be remembered 
that the ammonia at all parts is at practically the same tem- 
perature, since there is little drop of pressure through the cooler. 
The brine cooler shown in Fig. 83 is that built by the Baker 
Co. The ammonia lies in the inclined inner tubes and is intro- 
duced at A , passing down to the various pipes. The vapor is 
drawn through the nozzle B, and up to the separator C to the 
outlet D. Any liquid taken up is removed by the separator 
and sent back .through E. Brine enters at F and leaves at G. 
The connections are made by return bends. 



TYPES OF MACHINES AND APPARATUS 163 




164 



ELEMENTS OF REFRIGERATION 




TYPES OF MACHINES AND APPARATUS 



165 



Steam Condensers. The ordinary forms of steam con- 
densers can be used when desired, but because of scale troubles 
and because so much condensation is demanded for distilled 




FIG. 84. Arctic Oval Flask Steam Condenser. 

water in ice plants this is done at atmospheric pressure in 
flask condensers. Fig. 84 is made of sheet iron. Water is dis- 
charged over the surface of the flask and condenses the steam 
within. The outside and inside surfaces of the condenser may 




FlG. 85. York Steam Surface Condenser. 

be cleaned easily. In Fig. 85, the regular shell type of steam 
condenser is shown. The tubes are of brass and although 
usually held in place by soft packing they are expanded in the 
brass tube sheets in the figure shown. The left-hand tube 



166 



ELEMENTS OF REFRIGERATION 




TYPES OF MACHINES AND APPARATUS 167 

plate with the water head is allowed to expand back and forth, 
thus caring for expansion. The steam fills the whole inner 
chamber of the shell and passes around the left-hand tube 
sheet and cap. 

One of the latest developments of refrigerating machines 
is the Westinghouse-LeBlanc evaporative refrigerating machine 
shown in Fig. 86. This was described by Mr. J. C. Bertsch 
before the American Warehouseman's Association in December, 
1915, and reprinted in Power for January n, 1916. In this 
a high vacuum is maintained in the evaporator A by means of 
a series of steam nozzles B, from which steam at a high velocity 
issued, entraining with the jet any air or vapor which may be 
around the steam jets in the space C. By making the nozzles 
long enough and of proper shape the final pressure of the steam 
will be low at the end of the nozzle. The jets of steam and 
entrained air and vapor enter a diffuser D where the velocity 
is decreased and the pressure increased to such a value that 
the steam and vapor may be condensed by the water supply 
in the condenser E. This is supplied by the circulating pump F, 
the water coming from the cooling tower G which has received 
the warmed circulating water from E. The air pump H is 
a Westinghouse-LeBlanc centrifugal air pump and withdraws 
the condensation and air from E. The water of condensation 
is discharged into / and is cooled by a coil and flows back as 
sealing water for the pump. 

A high vacuum existing in B means a high vacuum in A , 
and consequently the brine in the tank J is sucked up into 
this vessel and passes through the perforated plate K into 
an inner chamber, where it is broken up into a number of drops 
which, falling through the space of low pressure, are subject to 
evaporation of part of the water content. This of course 
cools the brine ojfcftecarii^^bihe heat of evaporation coming 
from the liquid, and by the time it reaches the bottom of the 
evaporator it is cool enough to be circulated by the brine pump 
L through the brine system M, after which the warmed brine 
is discharged into the surge tank or receiver /. The brine 
has been concentrated in A by evaporation and consequently 



168 



ELEMENTS OF REFRIGERATION 



water must be added in / to reduce the concentration by the 
proper amount. This is done by the float valve. The various 




pumps are operated on the same shaft by a steam turbine. 
The stuffing-boxes of the brine pump are water sealed to keep 
out the air. 



TYPES OF MACHINES AND APPARATUS 169 

The ejector B, composed of nozzles and the diffuser, are such 
that the vacuum earned h^is a temperature of boiling of 50 below 
the temperature of the cooling water used in the condenser. If 
a lower temperature is desired, say 70 to 100 below the cool- 
ing water, two of these are used in the series, as shown in 
Fig. 87. 

Binary refrigeration is the name given to the use of a mix- 
ture of two different refrigerating media such as CO 2 and 
SO 2 . There has been no gain shown from the use of these. 
The late Mr. E. Penney reports in the Transactions of the 
American Society of Refrigerating Engineers experiences of 
himself and others in this field. 

In all refrigerating apparatus the use of thermometers is 
important. By their use combined with that of the pressure 
gauge the action of the apparatus may be known. Thus the 
condition of the vapor entering the compressor may be known 
by the temperature of the vapor at suction pressure, and by 
thermometers in the discharge pipe the quality of the suction 
vapor may be known by the amount of superheat in the dis- 
charge gas. The water and brine temperatures tell whether 
the surfaces are dirty. All instruments are of value in the 
proper operation of a plant. 

Cooling Towers. Where water for condensing is scarce 
some method of cooling is necessary. Cooling towers are used 
for this purpose. In these, water is allowed to flow over screens 
of galvanized wire, glazed tiles, wooden slats or some other form 
of baffle to break the water up into small particles, and while 
in this condition it is brought in contact with air, which will be 
heated and absorb some moisture. The heating of the air 
cools the water and the evaporation of the water taken up by 
the air removes more heat. This is the principle of the cool- 
ing tower: the heating of air and the evaporation of part of 
the water removes sufficient heat to cool the main body of the 
water so that it may be used again. Of course the only place 
from which the heat of vaporization and heat for the air can 
come is the water. 

Fig. 88 illustrates one form of cooling tower. In this hot 



170 



ELEMENTS OF REFRIGERATION 



water is pumped through the pipe C to the boxes D D arranged 
at the top of the tower on the sides. This water then flows 
into a series of pipes E, which are slotted on top, from which 
it flows over the mats B. made of wire screens. The air 




. Cooling Tower. 



blown in by four fans F meets the water falling in small drops 
over the screens. Here it is warmed and as its moisture capac- 
ity increases there is some evaporation. The tower proper 
is made of sheets of steel stiffened by angle irons. 

If a sheet metal top is placed above the top in the form of a 



TYPES OF MACHINES AND APPARATUS 



171 



chimney, the fans may be 
omitted, as the chimney 
effect is sufficient to cause 
the proper circulation of air. 
In some of these cooling tow- 
ers glazed tiles on end form 
the surface over which the 
water is discharged. Such 
a tower will require about 
0.2 sq.ft. of ground area per 
gallon of water cooled pei 
minute. 

In the Hart Cooling Tower 
shown in Fig. 89 there is no 
fan. The tower consists of a 
series of cooling decks C, D, 
E, F, spaced from 3 to 7 ft. 
apart, depending on the 
amount of cooling and the 
quantity of water to be 
cooled. The cooling decks 
are made up of trays placed 
in a staggered position on the 
upper and lower flanges of 
the I-beam supporting the 
deck. The water from the 
supply pipe A is delivered 
through a set of spray noz- 
zles B above the first set of 
trays and there falls over the 
successive trays, a total drop 
of from 20 to 50 ft. The 
splashing of the water as it 
strikes ths tray causes it to 
fall in drops. To prevent 
the spray from being lost 
the projecting shields G are 





FIG. 89. Hart Cooling Tower. 



172 ELEMENTS OF REFRIGERATION 

added. These not only catch the water blown away but they 
drive the air down into the tower when the wind is blowing, 
causing it to rise through the center or on the other side. In 
this way the wind is applied to operate the tower and in calm 
weather the chimney effect from the heated air causes a cir- 
culation. The moisture in windy weather is usually caught on 
the leeward shield and delivered to the next deck. This and 
other atmospheric towers occupy from i to i| sq.ft. of ground 
area per gallon of water per minute. 

In Fig. 90 the Thomas nozzle, used to spray water over 
a basin, is shown. In this the hot water is pumped to the 
nozzle and is delivered in a fine spray. The discharge orifice is 
made by the helical opening between the edges of a strip formed 
into a helix. The amount of opening may be regulated by 
the central spindle operated by a rod which controls all of the 
nozzles as shown. This spray of water warms the air and 
permits evaporation, so that the water falls to the tank or 
pcnd in a cooler condition. These ponds into which the spray 
falls should have about 2 sq.ft. of area for each gallon per minute 
flowing. 

Another method of cooling water is to discharge it into a 
cooling pond and to cool it by surface evaporation, the hot 
water entering at one end. If the pond is sufficiently large the 
water is cooled by the time it reaches the other end of the 
pond or reservoir from which the cooling water is taken. 
These ponds should have about 70 sq.ft. per gallon of water per 
minute or 9 sq.ft. per horse-power hour per day. 

In all of these arrangements the cooling has been done 
by the heat utilized to warm air and evaporate water. The 
heat to do these two things has to come from the water and hence 
the water is cooled. The amount of moisture which the air 
will carry is called the amount to saturate it. The air will 
carry no more moisture at a given temperature, but since the 
amount to saturate it varies with the temperature the capacity 
is increased by warming the air. Thus if at 75 i cu.ft. of air 
will carry 9.4 grains of moisture, the quantity is increased to 
14.9 grains if the temperature is increased to 90. If air at 75 



TYPES OF MACHINES AND APPARATUS 173 





174 ELEMENTS OF REFRIGERATION 

contains only 4-7 grains per cubic foot it is said to be one-half 
saturated and it could take up 4-7 grains more before satu- 
ration is reached. If at the same time the temperature were 
raised to 90 it would take up 10.2 grains before reaching sat- 
uration Now this evaporation removes heat and it is one of 




FIG. QI. Wet and Dry Bulb Hygrometer. 

the important methods of removing heat in a cooling tower. 
That cooling towers may evaporate water on rainy or freez- 
ing days when the air is saturated is seen to be possible by the 
figures above, when it is remembered that the air is raised in 
temperature and with it the capacity for moisture. Thus air 
entering at 75 and saturated will require an evaporation of 
5.5 grains per cubic foot of air to saturate it at 90 if this is 



TYPES OF MACHINES AND APPARATUS 175 

the temperature of leaving. In most cases the air will leave 
at or near the temperature of the hot entering water and hence 
the capacity for moisture is increased. 

The amount of evaporation per cubic foot of air will depend 
on the amount of moisture in the air at entrance. The condi-- 
tion of air is given by its relative humidity. This is the ratio 
of the amount of moisture in a cubic foot of air to that required 
to saturate it, as was stated on page 50. The instrument used 
to determine this is called a hygrometer, and the simplest form 
is the wet and dry bulb thermometer type shown in Fig. 91. In 
this instrument one thermometer has a wet wicking around 
its bulb and on whirling these in the atmosphere the amount 
of evaporation from the wicking is fixed by relative humidity 
and is shown by the drop in temperature. By reading the 
wet and dry bulbs and the barometer Carrier's equation (38) 
on page 51 may be used to find the relative humidity. This 
formula has been used to form the chart of Fig. 92, so that the 
figure may be used to find the relative humidity for different 
temperatures of wet and dry bulb, since barometric changes 
are not sufficient to produce much variation. The chart also 
gives the amount of moisture per cubic foot at any condi- 
tion. 

The air required by a tower for a given amount of water 
is found by equating the energy in the substances entering 
and leaving. It is found that the water may be cooled to 
a temperature much below the atmosphere in dry weather, 
the final temperature being about 5 above the wet bulb 
temperature. In times of high relative humidity of 70 or 
75% the water will leave at about the atmospheric tem- 
perature, but when the relative humidity is 40% it may be 
from 10 to 15 below the atmosphere, showing that the evap- 
oration of water has produced the principal cooling. The 
leaving temperature may be taken at about 5 above the wet 
bulb, although this may be i, 2 or even o above the air for 
high humidity. 

To compute the amount of water cared for by i cu.ft. of 
air entering the following method is used: 



176 



ELEMENTS OF REFRIGERATION 



150 




Relative Humidity 
FIG. 92. Relative Humidity and Moisture according to Carrier's Formula. 

Let t ua = temperature of dry bulb in air entering ; 
t,. w = temperature of wet bulb in air entering; 
t t d = temperature of dry bulb in air leaving; 
t'aw = temperature of wet bulb in air leaving; 

/ = temperature of water at exit; 

/' = temperature of water at entrance; 

P = relative humidity at entrance of air; 

p = relative humidity at exit of air; 
Bar = barometric pressure in pounds per square inch; 

p = steam pressure at temperature ^; 



TYPES OF MACHINES AND APPARATUS 177 

p' = steam pressure at temperature /'<. d ; 
m = weight of i cu.ft. saturated steam at .<*; 
m' = weight of i cu.ft. saturated steam at i' a(t ; 
M = weight of water entering per cubic foot of air at 

entrance; 
Assume: 



or 



Then 

Moisture per cubic foot of air at entrance = mp; 

Volume of air at exit per cubic foot at entrance 
i44(Bar p/>) 53-35 



i44(Bar-/') 
Moisture in air at exit per cubic foot at entrance 

Bar pp /' o 
- 



, , 



f , 
= -r ....... (10) 

Bar-/? /<i+46o 

Moisture absorbed = m" mp = m'" ..... (u) 
Energy entering tower: 
With i cu.ft. air 

p). (.2) 



With m Ibs. moisture = mpiJ ..... (13) 
WithMlbs. of water =Mq'.J ..... (14) 
Energy leaving tower: 
With air of V cu.ft. 



178 ELEMENTS OF REFRIGERATION 

With m" Ibs. of moisture =m"'i'J (16) 

With (M-m'"} Ibs. of water = (M-m'")q'J. . . (17) 

In these i' is the heat content of vapor in saturated or super- 
heated condition and q' is the heat of liquid. 

By equating these the quantity M may be found. This 
gives the amount of water per cubic foot of air entering, or the 
reciprocal will give the cubic feet of air per pound of water 
entering. In this way the air for a given amount of water may 
be found and the fan to introduce this air or the chimney to 

suck this air may be computed. The evaporation per pound 

in 
entering, -77-, will give the amount of make-up necessary. 

In designing nozzles for cooling fountains the assumption 
may be made that the evaporation will reduce the temperature 
provided the final temperature is above the wet bulb tem- 
perature. The number of nozzles may be found from the 
quantity of water by using the following data: 

The capacity of the spray nozzles of the Thomas form is 
150 gallons per minute under 4 Ibs. 'per square inch pressure. 
For ordinary spray nozzles the discharge in gallons per minute 
is given by the table: 



e, inches. 


5 Ibs. pressure. 


10 Ibs. pressure. 


I -S 


15 


21 


2.O 


40 


60 


2-5 


70 


QO 


3- 


1 2O 


140 



A velocity of 5 ft. per second at the entrance to the nozzle 
will give the discharge at 5 Ibs. pressure. The tank or reser- 
voir used with these nozzles should have about 2^ sq.ft. of sur- 
face for every gallon per minute. When the weather is warm 
a second spraying is necessary in successive nozzles over 
separate reservoirs. 

The cooling pond may be made of such a size that i sq ft 
will care for 3^ B.T.U. per hour per degree difference in tern- 



TYPES OF MACHINES AND APPARATUS 179 

perature between air and water; 70 sq.ft. per gallon per min- 
ute of water to be cooled has been suggested for the area of the 
pond. 

Safety Devices. There are several devices which are in- 
stalled in all plants using poisonous or suffocating gases to pre- 
vent loss of life and make the operation of the plant possible. 
One of the important ones is a helmet to wear over the head when 
it is necessary to enter a room filled with fum.es to repair a break, 




Fro. 93. Improved Vajen Helmet. 

to shut a valve, or to rescue a person. There are several of these 
in use. One of them is shown in Fig. 93. The Vajen helmet 
weighs 10 Ibs. and fits over the shoulders, being strapped tight 
on a wool gasket. The weight is carried by the shoulders, leav- 
ing the head free to turn. The air contained in the reservoir 
under pressure is sufficient for one-half to one and one-half 
hours' use. The helmet is made of fire and water-proof mate- 
rials, and by the large double-plate mica-covered openings 
guarded by cross bars one can easily see to work. Rotary 
cleaners are provided to clean these if obscured by smoke or 



180 ELEMENTS OF REFRIGERATION 

moisture. Telephonic ear pieces with special sounding dia- 
phragms enable the operator to hear distinctly and a whistle 
on front of the helmet makes it possible for the operator to 
signal others. 

The air reservoir is charged in two minutes by an air pump, 
and although this is a short time the reservoir should be kept 
charged. By opening the valve on the top reservoir air is 
discharged into the helmet in front of the nostrils of the wearer. 
This is above atmospheric pressure and forces the gases from 
respiration through the absorbent lambs-wool collar gasket and 
prevents the entrance of other gases. 

The top of the helmet is braced to protect the wearer against 
danger from falling objects, as the helmet is intended for use 
in fires or in chemical works. 

To guard against fatal results from accidents rules are 
made for the management and installation of refrigerating 
plants in large cities. Among certain rules formulated by the 
city of New York the following are noted: 

It is unlawful to operate a plant with gases under pressure 
without a license from the fire commissioner. 

An emergency pipe with valve outside to discharge gases 
into water sufficient to absorb full charge is to be installed. 

All refrigerating machines must be equipped with safety 
valves to discharge at 300 Ibs. per square inch pressure for 
ammonia, 1400 Ibs. for carbon dioxide, 100 Ibs. for sulphur 
dioxide and 100 Ibs. for ethyl chloride. These are to discharge 
into emergency pipes or to the low-pressure side of the system. 

There must be provisions for exit into the outside air or to 
a hall from which gas can be excluded for all rooms when the 
pressures are above the following limits: 

Ethyl chloride 40 Ibs. per square inch 

Sulphur dioxide 60 ' ' 

Ammonia 100 ' ' 

Carbon dioxide 500 ' ' 

All fittings are to be tested to twice the maximum pressure 
and pipes to three times the maximum. 



TYPES OF MACHINES AND APPARATUS 181 

No open flames are allowed in any rooms having pressure 
pipes. 

Helmets must be installed in all plants. 

Pipes are to be tagged showing kind of substance within. 

Storage of extra refrigerating substance will not amount 
to more than 10% of capacity. The cylinders cannot be kept 
in the boiler room but in some cool place. 

When the plant has a capacity of more than 3 tons the 
operator must have a certificate. 

The United States Interstate Commerce Commission has 
provided certain rules relating to the cylinders for the ship- 
ment of gases under pressure. Some of these are as follows: 

Cylinders must comply with requirements and be made of 
lap-welded pipe of soft steel of best welding quality. They 
may be made seamless. The heads should be welded in. The 
carbon is limited to 0.20%, phosphorus 0.11%, and sulphur 
-5%- The .cylinders must stand 1000 Ibs. per square inch 
in a water jacket to give extension which must not be over 
10% of volume. Cylinders must stand flattening out. They 
must be annealed. The cylinders must be stamped with name 
of owner. Gases which combine may not be shipped in one 
cylinder. Each cylinder must be tested once in five years 
under pressure. Test pressure is one and one-quarter times 
the pressure of vapor at 130 F., except for carbon dioxide 
cylinders, which are tested to 3000 Ibs. per square inch. 



CHAPTER V 
HEAT TRANSFER, INSULATION AND AMOUNT OF HEAT 

HEAT is transferred by radiation, convection and conduc- 
tion. In the first method a body starts a vibration in the 
ether, which is transmitted by it to another body which 
receives this energy of vibration and changes it into heat 
energy of the body. This form of transmission depends on the 
difference of the fourth powers of the temperatures of the two 
bodies. Although important in some cases, radiation does 
not play an important part in refrigeration. In the second 
method, particles of some medium, as air, are heated by a hot 
body and then by the bodily transfer of these heated particles 
the energy received by them is carried to a cooler body, which 
abstracts the heat. This method of heat transfer is one used 
for some types of refrigeration. The third method is that 
in which heat energy is applied to the molecules of one part 
of a body, and then by transmitting this energy to adjacent 
molecules the energy is gradually conveyed through the body. 
It is in this manner that heat is taken from cold storage rooms 
by the brine or ammonia, or heat is added to the room from 
the atmosphere. The last two methods of heat transfer must 
be examined in detail. 

If M Ibs. of substance are heated at constant pressure 
from a temperature t\ to h when the specific heat is c p , the heat 
required to do this is 

Q = Mc p (h-h) ....... (i) 

or 



(2) 



The first is correct if c p is constant, or is the mean value 
of c p , and. the second is correct if c p is a variable. The substance 
182 



HEAT TRANSFER, INSULATION 183 

usually employed is air, and although c p for air is not constant, 
the variation for the temperature ranges used in refrigerating 
problems is negligible. Hence the first formula may be used 
with a value of 0.24 for c v . If now the air is conducted to a 
room or cooler and is brought back to the temperature t\, the 
same amount of heat must be abstracted, and so the heat Q 
taken from the first body has been given to a second body 
and the air or carrying medium has been left in its original 
condition. This heat has been carried by convection. 

In conduction the heat transmitted depends on the mate- 
rial, the temperature, the cross-section of the material and 
the length of the path. The equation for conduction is similar 
to that for the flow of the electric current. 



F = aiea. of cross- section in square feet; 

/ = length of path, or thickness, in feet; 

/ = temperature on either side in deg. F.; 
C = constant of conduction, or B.t.u. per hour per square 
foot per degree for i ft. thickness. 

The value of C has been determined by various experiments, 
and by its use the amount of heat conducted can be predicted. 

When heat is transmitted through partitions, it is difficult 
to compute the amount of heat transmitted because it is hard to 
determine the temperatures at the edge of the plate on account 
of films of fluid which cling to the surface and make heat trans- 
mission difficult. Thus, if heat from the gases of a boiler 
is to be taken into the water in contact with the tube, and 
Eq. (3) is used to compute the probable heat transfer, using 
the C for steel of thickness /, and substituting the temperatures 
of the gas and boiling water, the heat would be equal to more 
than 250 times the amount actually transmitted. The great 
reduction is due to the effect of the films of gas and water 
which cling to the sides of the tube and cut down the heat trans- 
mitting power. A thin film of gas or water has a much greater 



184 ELEMENTS OF REFRIGERATION 

resistance than a thick wall of metal. The transmission through 
the gas or water film could be computed if the thicknesses were 
known, but these are quantities which vary, depending largely 
on the velocity of the fluids over the surface, and also upon 
the viscosity of those fluids. On account of this action exper- 
iment has been resorted to to determine a constant K, which 
is the amount of heat transmitted per square foot per hour 
per degree difference in temperature for the surfaces trans- 
mitting heat. Since in many cases the surface effects are the 
controlling factors, and not the main body of the partition, 
the thickness of the partition will not enter into the expression. 
With K the equation for heat transmitted becomes 



(4) 



A>B.t.u. per square foot per hour per degree; 
F = area in square feet; 
t = temperature in degrees F. 

The value of K is now determined experimentally for the 
transmission of heat through metal walls in condensers, 
absorbers and such apparatus, and it is found that as the veloc- 
ity of the liquids on either side increases the value of K 
increases. It is also found that for greater differences in 
temperature the value of K changes, becoming less usually 
as the temperature difference increases. For the temperature 
differences usually found in ammonia and steam condensers, 
brine coolers, feed-water heaters and such apparatus, the 
value of K found in experimental work with a given set of 
temperature conditions may properly be used with other tem- 
perature conditions since there would not be enough change 
in temperature difference to affect the value of K. 

If K is a constant and the temperatures on one or both sides 
change along the length of the surface it is necessary to find 
the mean temperature difference in terms of the temperatures 
at the ends of each surface. -Suppose that t hl and t hl are the 
temperatures on the warm side at entrance and exit and that 
t Cl and tet are the temperatures at the same ends on the cool 



HEAT TRANSFER, INSULATION 185 

side of the surface. At any point x the temperatures on the 
two sides will be t hx and t cx . The amount of heat transmitted 
through the differential surface at this point measuring from 
first end will give a rise in temperature of dt c to the cool sub- 
stance of M c pounds per second, and there will be a drop dl* 
on the warm side where M h Ibs. per second flow. Hence 

KdF(t hx -t Cl ] = -36ooM h c h dt h = ^6ooM c c c dt c .. . (5) 



As dF increases dt h decreases and dt c increases for parallel 
flow but decreases for counter current flow. The upper sign 
refers to parallel current flow. 



......... (6) 

Now 

M h c h [t hl -t ht ] 
or 

M h c h 



M c c c 
Also 



~ 



M c c 






186 ELEMENTS OF REFRIGERATION 



Afe 



= T~~7f T~~ vf loe ~t~* ' 





I 


A/2 




1< 


3ge ATi _Heat added 




r 


, A . /N rT- . o 

/2~~^H -*- 


Now 








Heat = F 


^(meanA/). 


Hence 








Mean At - A 


or -. 



Afe 



This then is the value for mean A/ to use in formula (4) 
for the solution of heat transfer problems. 

If K has the value K ' = Tn. . . . . . . . (15) 



This leads to 

^ (16) 



1 -"X J F. . s . (17) 

The values of Xjgiven by various authorities are as fol- 
lows: 



HEAT TRANSFER, INSULATION 187 

K= 3 from gas to gas; 
= 5 from liquid to gas; 
= 250 from liquid to vapor; 
= 400 from liquid to liquid. 

The average values can be used in case of need, but more 
exact values are given below. These show the effect of velocity 
and also show the need of special experiments. 

Values of K. For ammonia condensers of the double type 
form, the values of K as determined by R. L. Slupman in the 



3 ;ioo 



1 234 56 78 9 10 11 

Velocity Feet per Sec. of Water 

FIG. 94. Slupman's Values of K for Double Pipe Condensers. 

Transactions of the American Society of Refrigerating Engi- 
neers for 1907 are given in Fig. 94. The values of K may be 
taken from these curves. In Fig. 95 the values of K for brine 
coils are given at different velocities. The first of these curves 
has the equation 

K = isoVW w (18) 

W w = velocity of water in feet per second. 
The equation of the second curve for brine coils is 



K = 



188 



ELEMENTS OF REFRIGERATION. 



Some allow 100 for K for double-pipe coolers and condensers. 
Fred Ophuls has stated that his experiments .indicate that 
for double-pipe condensers 

W m = relative mean speed of ammonia and water in feet 
per second. The velocity of the ammonia may be taken as 
one-half the velocity of the vapor at inlet to condenser. 




300 
Feet per Min. Brine 

FIG. 95. Slupman's Values of K for Brine Coils. 

He also gives the following : 

For condensers of the Block type and for atmospheric 
single-pipe condensers the experimental results were given by 

W v = velocity of vapor at entrance in feet per second. 
For the cooling of the superheated vapor the constant falls 
off, being 

K = S.^VW m s: (22) 

W ms = mea.n speed of superheated vapor in feet per second. 
Thomas Shipley gives 60 as the value of K for open atmos- 
pheric condensers and 300 as the value in the Shipley con- 



HEAT TRANSFER, INSULATION 189 

denser, in which part of the liquid ammonia is forced through 
with the incoming vapor so as to wet the inside surface of the 
condenser. (See Fig. 77.) 

Rules used in practice may be mentioned. One requires 
40 sq.ft. of open air condenser surface per ton of refrigerating 
capacity and 25 sq.ft. for submerged condensers. These rules 
are to be used as checks. In many cases 18 sq.ft. are used 
per ton while Block condensers have been operated success- 
fully at 8 sq.ft. per ton. 

For brine coolers and brine tanks the value of K would 
be 50, although experiment must be made to find the effect of 
velocity more accurately. 

For brine coolers Fred Ophuls and V. R. H. Greene found 
that although the values of K from their experiments were not 
correctly given by any equation, their experiments when there 
is no superheat were best represented by 



K = 20.6V o. 52 iWa+Wt, ..... (220) 

W a = velocity of ammonia vapor at outlet in feet per second; 

Wn = velocity of brine in feet per second. 

When this ammonia leaves in a superheated condition the 
coefficient is changed to 15.2. 

Levey gives as a rule the allowance of 55 sq.ft. of expansion 
coil per ton of refrigeration with at least 60 cu.ft. of capacity 
of brine in tank per ton. This is only a check on the computa- 
tion for K. The York Mfg. Co. uses 108 sq.ft. of direct expan- 
sion coil per ton of capacity. This is 250 [lineal feet of i^-in. 
pipe to ton. With ordinary piping, without flooding the 
coils with ammonia, 350 ft. of pipe may be used. Some have 
found that the formation of ice around the expansion coil in 
a brine tank increases the rate of heat transmission; i in. 
of ice increased the transmission to 1000 B.t.u. per foot per 
hour of i|-in. pipe and 2 ins. trebles this. 

For liquid fore-coolers the constant is given by 

(23) 



= velocity of the liquid in feet per second. 



100 ELEMENTS OF REFRIGERATION 

The value of K for coils in rooms from brine or ammonia 
to air, should be taken as about five, although Siebel states that 
ten could be used. Since ice and snow are deposited on pipes 
in refrigerated rooms, these constants cannot be used and the 
allowances employed in practice are given. These are as 
follows : 



For direct-expansion pipes 
(Siebel) 



For brine pipes (Siebel) 

For brine pipes (Levey) small 
rooms 

Room 1000 to 10,000 cu.ft. 
Rooms over 10,000 cu.ft. 



ft. of 2-in. pipe for 10 cu.ft. of space at 10 F 



32 
5 
35 
10 
32 
So 
o 

10 

32 

o 

10 

32 

o 

10 

32 



About 50 sq.ft. of pipe will care for i ton of refrigeration 
and 100 sq.ft. of pipe for i ton of ice manufactured. 

INSULATION 

When the thickness of insulation is great or when the 
resistance of the internal portions becomes appreciable when 
compared with the resistance at the surface, the Eq. (4) is used 
to find the heat transmitted by the partition, and K is com- 
puted for the various elements of the partition. This is the 
problem of heat transfer through walls. 

The heat loss from rooms is made up of several parts. There 
are radiation and conduction from walls, windows and doors 
and convection losses due to warming of the leakage air, or the 
air for ventilation. There is a gain of heat derived from per- 
sons or apparatus used in the room, or from sources of light 
of various kinds. The heat loss through walls partakes of 
. the nature of radiation and conduction. The principal loss 
is made up of transmission, which is found to depend on the 



HEAT TRANSFER, INSULATION 



191 



difference of temperature and therefore it is similar to con- 
duction rather than radiation, which depends on a higher 
power of the temperatures. The general form in which this 
heat loss is given is 

H = KF(t l -t ), (24) 

where F = area in square feet; 

K = heat transmitted per square foot per hour per degree 
difference of temperature in B.t.u.; 

/i=room temperature in degrees F.; 

/o = outside temperature in degrees F.; 

H = B.t.u. transmitted per hour. 

The value of K depends upon several factors: the surface, 
thickness and kind of material, air spaces and condition of 
air at surface. It also depends on temperature difference, 
but since the temperature differences are not large, this effect 
may be neglected. The following German method from H. 
Rietschel's Leitfaden zum Berechnen und Entwerfen von 
Luftungs- und Heizungs-Anlagen is usual for future reference 
for cases which have not been calculated in the text. 

The rate of transmission of heat through any substance 
depends upon the thickness 
and on the difference of tem- 
perature. If for instance the 
wall shown in Fig. 96 is made 
up of several thicknesses, and 
the temperatures are those 
marked, the equations for the 
transmission of heat through 
each section must give the 
quantity of heat transmitted 
by the wall, and these therefore must be equal to each other. 

The amount of heat conducted by any material per square 
foot of cross-section varies directly with the temperature dif- 
ference and inversely with the length. This gives 

C, 

# = -(/i fc), ( 2 5) 




FIG. 96. Wall Section, 



192 ELEMENTS OF REFRIGERATION 

where C is the constant of conduction for i ft. thickness in 
B.t.u. per square foot per degree, / is the thickness in feet 
and ti-h is the difference of temperature. Using this for the 
wall shown in Fig. 96, the following results: 

/I /2 ^3 

At the surface of any material there is to be found a temperature 
different from that of the contiguous space and it is this differ- 
ence which determines the flow of heat at the surface. 
At the surface the same formula 



holds, but since / is difficult to find, the quantity j has been 

replaced by a and experiment is used to find the value of this 
for different materials and conditions of the surface. If a 
is the coefficient of transmission per square foot per hour 
per degree across this surface, this becomes at different sur- 
faces: 



a 2 (/" 2 -/ 2 ) 



(27) 



The values of H in the sets above are all the same quantity, 
hence solving for temperature differences and adding, the fol- 
lowing results : 



i a 2 a 3 2 3 a 

Now 



Hence 

*"I^T^ L lTT~fc > ' ' (29) 



HEAT TRANSFER, INSULATION 



VALUES OF C 



193 



Air, still 
Air in motion 
Asbestos paper 
Blotting paper 
Brass 
Brickwork 
Building paper 


0.03 
0.09 
o . 04 
o . 04 
61 .00 
o . 46 
o 08 


Lead 
Limestone *: 
Lith 
Marble, fine 
Mortar and plaster 
Mineral wool 
Oak 


. . . 20.00 

i-3S 
... 0.028 
... 1.88 
. . . 0.46 
0-05 


Cement 
Charcoal. . . 
Copper 
Coke 
Cork, compressed 
Cork , granulated 


o . 40 
0.03 
202.00 
0.05 

0.022 

o . 03 


Pine (along the grain) 
Pine (across the grain) 
Plaster of Paris 
Sandstone 
Sawdust 
Shavings 


. . . 0. II 

. . . 0.06 
... 0.34 
... 0.87 
... o. 03 






Slate 




Feathers 


o 040 


Terra-cotta 




Felt 


o 02 


Tin 




Glass 


o . 54 


Wool 




Hair felt 


0.026 


Zinc 


. . . 74-00 



The values of the quantities a, as given from Grashof and 
Rietschel, are of the form 



(30) 



10,000 



d and e are constants, d depends on the condition of the air 
around the surface and e depends upon the material. T is the 
temperature difference between the air and the surface at any 
point. 

To determine the quantity T, a method of approximation 
is used until by practice one knows what to expect. The value 
of the term involving T, 



10,000 



is small, hence for a first approximation this term may be 
neglected and the value of the various #'s may be found. 
These may then be used to find K. 



K 



I 



C 



194 ELEMENTS OF REFRIGERATION 

after this is known the following results: 

K(h-t Q }=a l (t,-t'i)=(i2(t2-t' 2 } 

= a\Ti = a,2To = etc., 
r = /i-/'i or t"o-t . 

These equations give the first approximations for T. 

In this way after T is found as a first approximation, the 
value may be used to find a second value of a and then a new 
value for T. In this way two or three trials will lead to the 
correct result. 

In any case the value of T is small and this is true par- 
ticularly for thick walls or in cases in which ti to is a small 
quantity. 

Rietschel gives results used in practice for the value of T 
for masonry walls. These may be put into the form of an 
equation, 

T =16.2-4.001 (32) 

This may be used for masonry walls with air spaces where / 
is the sum of the various thicknesses of masonry, although 
the result is slightly too large in this case, as the quantity 
K(t\to) is smaller than for a solid wall of the combined 
thickness. 

For a single glass T is taken as \(t\. fa), while for double 
windows |(^i~^o) is taken at each surface, since glass is so 
thin there is practically no temperature drop in it, the 
main resistance being at the surface. 

The value of T for wooden floors is given as r=i.8 F. 
The values of d as given from Grashof are as follows: 

VALUES OF d 

Air at rest as in rooms or channels 0.82 

Air with slow motion as over windows i . 03 

Air with quick motion as outside of building 1.23 

The values of the coefficient e are determined by Rietschel 
as follows: 



HEAT TRANSFER, INSULATION 



195 



VALUES OF C 



Brass, polished 
Brickwork and masonry. . . . 
Cast iron, new 


... 0.05 
... 0.74 
... 0.65 


Polished sheet iron 
Rusted iron 
Sawdust. 


Cotton 
Charcoal 
Copper 
Glass 
Mortar and lime mortar. . . . 
Paper 
Plaster of Paris 


0-75 
... 0.71 
... 0.03 
... 0.60 
... o . 74 
... 0.78 
. .. 0.74 


Sheet iron 
Tin 
Water 
Wet glass 
Wool 
Zinc 
Wood 



. O.OQ2 
. 0.69 
. . 0.72 

o-S7 

0.045 
1.07 

. 1.09 

. 0.76 

. 0.049 

o-74 



To explain the application of the above the wall given in 
Fig. 97 will be investigated. The wall is composed of 4 ins. 
of sandstone, 18 ins. of brick work, a 2-in. air space, 8 ins. 
of brick and i in. of plaster. Where sections of the wall actually 




FIG. 97. Wall Section. 

come in contact, there is no surface resistance and the wall 
may be considered as solid except for differences in values 
of C for the various materials. When air can circulate it is 
not considered an insulator as the convection currents carry 
heat from the warm to the cold side. The value of air space 
is in the surface resistance. To find a the various values 
of T must be known; now T is given by the following: 



To = t f 'o to. 
These quantities vary inversely with the different values of 



a\ T\ = ai 



196 ELEMENTS OF REFRIGERATION 

As the quantities a do not differ by great amounts these 
various values of T are considered as equal quantities in com- 
puting a. 

T may then be found from the equation 

r-i6.2-4.0ol. 

In this case the total thickness is 31 ins. and 



. (42X1.23+31X0.74)6. 
"4 = 1.23+0.74+^ 10,000 -' 

a3 = a 2 = a 1 =o.82+o.74+^-^^ ^ > ^ 4j6! ; 

10,000 



as = i. 59 = #2 = 



1,1,1,1., 0-33 , i.S , Q-66 { 0.083 

2.OI 1.58 1.58 1.58 0.87 0.46 0.46 0.46 



0.497+0.633+0.633+0.633+0.379 + 3.26 + 1.435+0.180 

I 

= = 0.131. 

7.62 

The resistance of air channels is negligible because of the 
convection currents. 

For a floor or ceiling as shown in A, Fig. 98, the method 
is quite the same. When the high temperature is at the 
top, however, there is no circulation in the air space between 
the plaster and the floor and the air acts as an insulating 
material. 

When the high temperature is below or if an air space is 
in a vertical position, the circulation of the air transmits heat 
by convection and the air does not act as an insulating material. 



HEAT TRANSFER, INSULATION 



197 



In any case, however, there is a resistance at the surface between 
the air and the partition due to the drop T. 

When the same constant K does not hold over a complete 
wall or floor owing to a change in the construction as occurs 
at studs in a partition or joists in a floor, the value of K for the 
whole surface is found thus: 



K = 



2KF 



(33) 







1 




! 


*-&! 


| 










. 




d 





is* 



A T 1 
FIG. 08. Floor Sections. 



In most cases the areas F have a common dimension, so that 
the areas are proportional to the widths. If these are bi and 62 
there results (Fig. 98), 



K 



(34) 



The mean constant is not usually found for a wall in terms of 
glass and wall coefficient, as these are kept separate, but there 
is no reason why this could not be done, as happens with 
the coefficient for partitions with partition studs in the cases 
which follow. 



198 ELEMENTS OF REFRIGERATION 

With the high temperatures above the air acts as an insu- 
lating substance and the following for the floor, Fig. 98 : 



10,000 

at joists, 

i 

Ki = =0.0^ 

i , _i3i 2 5_ + 5_ , i 

1.57 12X0.06 8X12X0.46 1.57 

at space between joists, 

K a = 

=0.027 



1.57 12X8X0.06 1.57 12X0.03 8X12X0.06 8X12X0.46 1.57 

Combined 

^3X0.05 + 13X0.027 
16 

With the high temperature below on account of the convection 
currents, the air does not act as an insulating substance and 
the following results: 



^,=0.05; 



K a 



=0.22; 



1.57 12X0.06 8X12X0.46 



1 6 



This method may be used for various walls and partitions. 
The following values have been computed by the author and 
these values compared with those given by Kinealy, Riet- 
schel and others. 



HEAT TRANSFER, INSULATION 199 

Values of a 
For brick and plaster or masonry. 

Outside a = I . 23 +o. 74 +><L?33.i.X2i4 

10,000 

= i. 97 +0.0075 T 

= 2.09 o.03/, 

since T =16.241. 

Inside a = 1.56+0.00577 

= 1.65 0.023/. 

For wood and, approximately, paper, cotton, wool, coal 
and sawdust : 

Outside a = 1.97+0.00757 = 1.98. 

Inside (1 = 1.56+0.00577 = 1.57. 

For glass: 
Outside a = 1.83 +0.0077 






Inside with motion: 

a = 1.63+0.0067 

= 1.83(7 = 35). 

Inside without motion: 

a = 1.42 +0.005 7; 
-1.59(7-35). 

Inside with motion and wet from condensation: 

a = 2. 1 1 +o.oo87 
= 2.39. 



200 ELEMENTS OF REFRIGERATION 

; , 

For double windows: 

Outside a = i.95(r = |X7o); 

Center a = 1.51. 

Inside, dry a = 1.74. 

Pipe Covering. The use of pipe covering to prevent the 
conduction of heat from steam pipes or to brine pipes or vessels 
must be considered in this chapter. The discussion applies 
to covering on all circular bodies. The constants of this 
chapter may be used in this case. The transmission formula 
now becomes 



For flat plates of insulating material the expression to be 
used is 

Q=F-f(*>-*i). 
For cork c = 0.022. 
For 

Q = heat per hour in B.t.u. ; 
c = B.t.u. per hour per degree for i ft. thickness; 
TQ = radius outside of covering in feet; 
ri = radius of pipe in feet; 
Z, = length of pipe in feet; 
F = area of surface in square feet; 
/ = thickness of covering; 
to = temperature outside covering deg. F. ; 
/i = temperature inside of covering deg. F. 



HEAT TRANSFER, INSULATION 201 

Mr. L. B. McMillan has recently given values for c for 
various temperature differences. 



VALUES OF C 



Temperature Liffe 
Kind of Covering. 



2 5 


50 


I 
75 | ioo 


150 


200 


500 


400 



Johns-Manville asbestos sponge. 0.027 0.028^0. 028:0. 020 0.030 0.031 0.03210.036 
Nonpareil high pressure ....... o. 035:0. O35 : o. 035 0.03, .0.054 0.034 0.0350.037 

Gary 85% magnesia .......... '0.034 '0.034 0.054 0.05410.035 :>. 05 5 0.036 0.038 

Johns-Manville magnesia ...... !o.o36 0.03610.036 0.036 

Carey carocel ................ 0.029 0.03010.03110.032 



Johns-Manville asbestocel ..... 0.035 O- O 35-O35[0. 036 0.03710. 038'. O4io. 045 
Johns-Manville aircell ......... 0.0380.0380.0390.0400.04110.043 o. 047*0.054 



0.0370.0370.03710.039 
o. 03^0. 03510.03910.044 



The insulating of cold storage houses is accomplished by 
the use of wooden walls with air spaces as shown in Fig. 99, 
brick walls with wooden backing as shown in Fig. 100, brick 
walls with air spaces as shown in Fig. 101 and brick walls 
lined with some non-conductor as shown in Fig. 102. The 
main purpose in using these is to increase the heat resistance. 
The older storage houses were of wood and the method shown 
in Fig. 99 gave good satisfaction. The use of paper or felt 
coated with some substance to waterproof it keeps the saw- 
dust and air space dry as well as making the wall air tight. 
Sawdust or mineral wool is used in the air space for the purpose 
of preventing air circulation. This is accomplished in air 
spaces by using horizontal strips which should be put at inter- 
vals between them. Fig. 100 shows a construction recommended 
by the Frick Company for warehouses. At times cement, 
concrete or asphalt is put on wooden floors as a wearing sur- 
face. Fig. 101 shows the brick type of insulation which is 
valuable although expensive. Where space is valuable some 
of the brick may be replaced by cork board or by lith as 
these have more resistance. The type shown in Fig. 102 
illustrates such a protection. Two thicknesses of cork board 
insulation with cement between are used to get the neces- 
sary thickness, as these boards are usually made no greater 



202 ELEMENTS OF REFRIGERATION 

than < ins in thickness. The cement is usually a tar, asphalt 
or some other waterproof binder. The surface is sometimes 
protected with a cement plaster of waterproof properties. 





FIG. 99. Wooden Wall with Sawdust Fill. (Elevation above, plan below.) 

At times air spaces are introduced between the various 
thicknesses of boards as shown in Fig. 103, and in some cases 
the outer layer may be replaced by two of lumber with paper 
between. The combination used depends upon the peculiari- 










FIG. ioo. Brick Lined with Wood. 




III. 

a " I I 

6 o <5 3 



FIG. 101. Brick Wall with Air Spaces FIG. 102. Wall with Lining of 
and Tile Lining. Cork or Lith. 

203 



204 



ELEMENTS OF REFRIGERATION 



ties of the designer. The Union Fibre Co. suggests the use 
of their linofelt as part of the construction. This is a felt 



2 I 

I 1 



i 



i 



FIG. 103 Brick Wall with -Wood 
Lining. 




FIG. 104. Use of Lith 
and Linofelt. 




FIG. 105. Floor Construction. 

made of flax fiber and held between two thicknesses of water- 
proof paper. The construction is shown in Fig. 104. 

Floors are insulated as shown in Fig. 100 and Fig. 105, 
when above the first floor, while for floors on the ground, Fig. 



HEAT TRANSFER, INSULATION 



205 



106 shows the method used. These are carefully drained and 
the endeavor is made to keep all moisture from the insulating 



& 8 
i .11 1 5 

!!!!! I I 




lp- /; ; 

V 'ffi$' : - '&'' ' ^' " ' \i yfity 


\$fy&*'&i'":3&ffljR^ 


Q 

~z_ 


^ ^S^^fw"^ 


3 

O 


Vf//r*X^*" ."^* ' ttlt- ' M^O-' 


S 

o 


\ ^^ss^^f^?^ 


z 

O 


^vvf .vV : ; <i ^^"-K^^ 

y j >V*"-"vv ; '-""-'"*"?;n^^^^^ 


a 
o 

3 

u. 


Mttiii^S 






material. Fig. 107 shows a form of wall using an interlocking 
and bonding section. 



206 



ELEMENTS OF REFRIGERATION 



The construction used in making grain bins consisting of 
planks 2 X 10, i X 10 or i X 1 2 laid on the flat side, has been used 
for cold storage structure by some builders with success. 
In some cases such walls have been veneered with 4 ins. of 
brick. All of the preceding drawings are given to show some 
of the many methods used. There may be many changes sug- 
gested. The general method for finding the insulating value 
of a wall has been given so that for any new type of construc- 
tion the insulating value may be determined before the con- 




Fir, . 107 Special Tile Wall. 

struction is made, in order to ascertain whether or not addi- 
tional expense would be justifiable. 

There are several elements entering into the problem of 
construction of a cold storage warehouse. Not only does 
the original cost and the insulating value enter into the prob- 
lem, but also the cost of insurance and depreciation must be 
considered. R. E. Spaulding and J. H. Nielson have pointed 
out that although a wood ice-house will cost $2.00 per ton of 
capacity, and a fireproof masonry or concrete structure cf the 
same insulating power will cost $2.50 per ton of capacity, the 
latter costs less to operate because the depreciation must be 
figured at 10% for the wood, and at 3% for the fireproof 



HEAT TRANSFER, INSULATION 



207 



structure, building insurance $5.00 per hundred on 80% of 
the wooden building and 40 cents on 80% of the fireproof 
building while for the ice the insurance is 5.00 for wood and 
40 cents for concrete per 100 tons of ice. Considering the 



^Concrete .Maple 




FIG. 108. Floor Construction. 

interest at 5% with the above items the yearly cost is 43 cents 
for the cheap wooden house, and 21 cents per ton in the fire- 
proof house. 

The methods of this chapter have been used to compute 
the values for various types of insulation and the results are 




FIG. 109. Reinforced Concrete Roof and Ceiling. 

given on p. 211. These values may be used, if desired, to 
make preliminary calculations. 

Fig. 108 shows a construction of floors using arches while 
Fig. 109 illustrates the method of hanging a ceiling on an 
inclined reinforced concrete roof to form an air space or to give 
a level ceiling. 

The construction of doors is an important question in the 



208 . ELEMENTS OF REFRIGERATION 

operation of a warehouse. Not only must these be non-con- 
ducting, but they should be air tight, because the temperature 
difference might set up a strong circulation of air through cracks, 
and this must be avoided. 

To prevent this, leakage doors were originally made as shown 
in Fig. no. The numerous corners caused troubles, and to 
do away with them other arrangements have been invented. 
Fig. in illustrates a section through the Stevenson door in 
which a hemp gasket is forced into place by the closing of the 
door. The No Equal cold-storage door is shown. In the former 
the soft gasket projects Jrom the door flange while in the latter 
the hair felt which is inclosed in a ring of canvas or rubber 
is placed in two grooves beneath a gasket of rubber or leather 
in the concave quadrant corner of the door. The jamb is 
rounded, removing all sharp corners which would be bruised 



FIG. no. Section of Early Form of Door. 

and which would prevent proper operation. The threshold of 
the doors requires special treatment. It should be beveled 
off to the floor line. The packing must be tight here to make 
a proper fit. 

In many cases, the insulation at doors is made more perfect 
by using a -vestibule before the main door, thus requiring two 
doors to be opened at the time entrance is effected. 

The insulation of ice tanks is shown in Fig. 112. The 
method of construction and computation is the same as that 
used above. The tank may rest on several layers of cork 
board or on wooden sleepers and the sides may be insulated 
with granulated cork. The heat loss must be cut down to a 
low value. 

In all of the above methods of insulation care must be taken 
to prevent moisture from entering the insulation, as the value 
is decreased when this becomes wet and the wood or material 



HEAT TRANSFER, INSULATION 



209 





Stevenson Doar. 



czc 



FIG. in. Arrangements of Doors. 



210 



ELEMENTS OF REFRIGERATION 



may rot. In addition the insulating material should be of such 
a nature that vermin cannot breed in it. 

To make the foundation waterproof the cement concrete 
may be treated with a chemical, but if this concrete cracks a 
leak occurs. To guard against this the concrete may be coated 
with a waterproof plaster, which is less likely to crack, or the 
foundation may be coated with coal tar or pitch and covered 




Asphalt 



.CorkT 

' Concrete 



FIG. ii2. Tank Insulation. 

with tarred felt and burlap covered with tar. Care must be 
taken to waterproof concrete, as water is drawn up by capil- 
lary attraction 10 to 20 ft. above the standing water. A good 
method of waterproofing is to use bitumen cement, which is 
strong but -not brittle, applying this on both sides of each of 
two or three layers of felt. For floors use two or three layers 
on top of the concrete floor and then apply top concrete. For 
roofs, a layer of brick may be put on top of felt followed by 
6 ins. of earth with grass. 

One of the chief points ; to consider is to make the yearly 
cost of refrigeration a minimum. This includes yearly cost for 
interest, depreciation, taxes and insurance on insulation, with 
cost of storage space as well as the cost of refrigeration. 

The values of K for different types of insulation have been 
computed and are given as follows: 



HEAT TRANSFER, INSULATION 

VALUES OF A' 



211 





Total Thickness of Brick Masonry. 


Walls. 






4" 


8" 


12" 


16" 


2O" 


24" 


28" 


32" 


Solid brick 


0-55:0-39 


0-31 


0.2S 


0.21 


0.18 


0.16 


0.15 


Solid brick with plaster 


0-51 


0-37 


o. 29 0.24 


0.21 


0.18 


0.16 


0-15 


Brick with one air space 




0.27 


0. 22 O.ig 


0.17 


o.i.S 


0.13 


0.12 


Brick with one air space and plaster .... 




0.26 


0.22 O.ig 


0.17 


0-15 


0.13 


0. 12 


Brick with air space, 4-in. tile and plaster 




O.I4JO.I3 0.12 


O.II 


O.IO 


0.09 


O.OQ 


Brick with 3-in. cork and plaster 


0.07 0.07 


O.O7 


0.06 


0.06 


0.06 


0.06 


0.06 


Brick with 2-in. cork, ^-in. cement, 2-in. 










1 






cork, ^-in. cement 


o . 06 o . 06 


0.05 


0.05 


0.05 


0.05 


0.05 


0.04 





















Walls. 


Sawdust 


Thickness. 






o" 


6" 


I 2" 


18" 


24" 


30" 


| in. wood, paper, 


5 


in 


wood 


sawdust, 














| in. wood, paper, 


i 


n. 


wood . 


o. 16750.044 0.025 , 0.018 0.014 


O.OII 


Same with shavings 


in 


place of sawdust. . . o. i67'o.o62 


0.039 0.028'0.022 


0.018 


| in. wood, paper, 


| in. wooc 


, sawdust, 








| in. wood, paper 
wood, paper, \ in. 


, I in 
wooc 


. wood 
. Fig 


, air, g in. 
99 


O. IO2 '0.038 


0.023 0.017 


0.013 


O.OII 


| in. wood, paper, 


1 


in. 


wood, 


air, I in. 




I 






wood, paper, 3 ins. 


cork, \ 


n. cement; 










plaster 








,0.057 










Same with 6 ins. cork 


0.036: 











PARTITIONS 

| in. wood, 12 ins. granulated cork, f in. wood K = 0.024 

\ in. plaster, 3 ins. cork boards, 4 ins. granulated cork, 

3 ins. cork board, \ in. plaster K = 0.027 

Tile partitions plastered single . A = 0.30 

Tile partitions plastered double K = o.2i 

FLOORS 

Fig. 108, ist figure A' = 0.02 2 

2d figure A' = 0.062 heated room below 

A = o . 030 heated room above 
3d figure K = o. 060 



212 ELEMENTS OF REFRIGERATION 

12 ins. concrete, 2 to 3 ins. cork boards, 2 ins. cement # = 0.038 

Glass, single thickness 

Glass, air, glass # = 0.41 

Glass, air, glass, air, glass K=o. 26 

6 glass and 5 air layers # = 0.12 






FIG. 113. Norton's Method of Finding K. 

The value of K for cork board has been found by Prof. 
Norton in several ways. In one case he built a cubical box 



HEAT TRANSFER, INSULATION 213 

of the cork to be tested, and placed a piece of ice within. By 
weighing the amount of water from the ice the heat carried 
in, was found. In a second test a fan was placed within the 
box and electric lamps or resistances were used to produce 
heat and by circulating the air the temperature was made 
uniform ; then by measuring the energy to hold the box at some 
temperature above the room temperature, the heat loss per 
degree was found. To get the area of the box surface, the sur- 
face of a cube at the mean thickness of the cork was computed. 
In addition to this the heat added to warm oil circulated in a 
tin lining on the inside of the box was found electrically 
and reduced to B.t.u. per square foot per twenty-four hours. 
Norton also placed a wire grid between two thicknesses of 
cork board. After allowing for heat losses at the edge by keep- 
ing grid at a certain state the heat loss in electrical energy per 
square foot per degree per hour was found. The mean value 
suggested by him for cork is K = 0.022. These methods have 
been used by German experimenters and others for the deter- 
mination of K for various substances. 

There are other elements entering into the heat supply 
of refrigerating plants. Any air leakage or ventilating supply 
must be cooled off. For M Ibs. of air per second, the heat 
per hour will be: 

Q = $6ooMc p (to-t i ) 



M = weight of air per second; 
c p = specific heat of air = 0.24; 
to = temperature outeide in deg. F. ; 
ti = temperature inside in deg. F. 
p = pressure in pounds per square inch; 
V = volume per minute in cubic feet at p Ibs. pressure 

and absolute temperature T\ 
= 53.35. 

The heat produced by persons is given by the following 
results by Benedict in the table below: 



214 ELEMENTS OF REFRIGERATION 

Adult at rest, asleep .......... 258 B.t.u. per hour 

sitting ........ . . 396 

Adult at light work ........... 670 

Adult at moderate work ....... 1150 

Adult at severe work .......... 1780 

For children an allowance of 300 B.t.u. per hour may be 
made. 

Heat of Machines and Lights : 

For electric lights ....... i watt-hour. ... 3 .41 B.t.u. 

For power ............. i K.W.-hr ..... 3410 

i H.P.-hr ...... 2546 

For gas where used : 
i cu.ft. illuminating gas ............... 700 B.t.u. 

i cu.ft. natural gas .................... 1000 

i Welsbach burner uses 3 cu.ft. of gas per hour. 
i fi?h-tail burner uses 5 cu.ft. of gas per hour 

If substances are chilled the following specific heats and 
constants in table on page 215 are used. 

These values have been obtained by reference to various 
authors and are collected here in a separate table. 

See Storage Rate Guide for rules relating to charges for 
storage, rules for labor charges, liability, etc. 

Having the amount of goods put in a storage room the heat 
per hour to cool this refrigeration in tons is : 



199.2 hx 199.2 

M weight of goods including weight of container; 
c = specific heat of substance; 
t a = temperature of outside air or temperature of goods 

put in storage ; 
t r = temperature of storeroom or temperature of goods 

after storage; 

^ = heat of fusion if goods are frozen; 
h = hours required to cool goods; 
Q = B.t.u. per hour. 



HEAT TKANSFER, INSULATION 



215 



COLD STORAGE DATA 







Specific Heat. 




Cost 


Cost 










Latent . 

HTime 


of 


of 




Substance. 


Temp. 
Deg. F. 


Before' After 


eat " 
F u . i Stor- 


i mo. 
Stor- 


Each 
Sue- 
cessive 


Unit of Storage. 






Freez. Freez. 


sion. j age " 


age. 
Cents. 


mo. 
Cents. 




Apples 


30-35 


0.92 .... 


.... 6 mo. 


20 


I S 


Barrel 


Bananas 


34-40 




.... ! 3 mo. 








Beans, green. . . 


36-40 


.91 .... 




10 


IO 


Bu. basket 


Beans, dried. . . 


40-45 


.90 .... 




15 


IO 


100 Ibs. 


Beef, fresh 


30-38 


.70 0.38 


90 3 mo. 


ito| 


Itoi 


ilb. 


Beef, salt 


40-45 


.60 




i 


i 


i Ib. 


Beer 


30-36 


.90 .... 




12* 


IO 


Half barrel 


Berries 


36-40 


.91 .... 


.... . short 


itoi 


i to* 


Quart 


Butter 


15-20 


.60 0.84 


84 5 mo. 


i 


i 


i Ib. 


Cabbage 


32-36 


.93 0.48 


129 1 .... 


20 


15 


100 Ibs. 


Cantaloupes. . . 


34-36 


.92 .... 




IO 


7* 


Box or crate 


Cherries, fresh . 


36-40 


.92 .... 


3 wks. 


15 


12 


* bu. basket 


Cherries, dried . 


40-45 


.84 .... 




I2i 


12* 


100 Ibs. 


Cheese 


32-36 


.64 .... 


.... 4 mo 


15 


IO 


100 Ibs. 


Celery 


34 


.91 




25 


25 


Large crate 


Cider 


30 


.90 




25 


2O 


Barrel 


Cigars 


40-45 






5 


5 


Per cu.ft. at $5 val. 


Dates 


40-45 


'. 84 '.'.. 




12* 


12* 


100 Ibs. 


Eggs 


30-31 


.76 0.40 


100 6 mo. 


IO 


7* 


30 doz. case, 55 Ibs. 


Fish, fresh 


~ 5 < 


.75 0.40 


100 8 mo. 


1 


J 


i Ib. glazing 


Fish, dried 


35-40^ 


.58 .... 




20 


15 


100 Ibs. 


Fruit, dried. . . . 


35-40 


.84 .... 




I2j 


!2* 


100 Ibs. 


Furs, coats .... 


25-30 






Si.50 t 


O 2.0O 


per season each 


Furs, rugs 


25-30 






$ .60 t 


o .75 


per season each 


Furs, uncured . . 


30-35 


... j .... 




$ .60 t 


o .75 


per season I cu.ft. 


Game 


15-20 


.80 0.40 


105 .... 


J 


i 


i Ib. 


Grapes 


32-36 


.92 


.... 2 mo. 


5 


4 


10 Ib. basket 


Grape fruit .... 


32-40 


.92 .... 


.... 3 mo. 


IO 


7* 


Box 


Lemons 


32-50 


.92 


.... 3 mo. 


IO 


7* 


Box 


Milk 


32-36 


.90 0.47 


124 


I2i 


12* 


40 qt. can 


Mutton 


30-32 


.67 0.81 


.... 5 mo. 


i 


t 


I Ib. 


Onions 


32-36 


.91 


.... 6 mo. 


15 


15 


2 bu. sacks 


Oranges 


32-50 


.92 ! 


.... 3 mo. 


IO 


7* 


Box 100 Ibs. 


Oysters, bulk . . 


30-34 


.84 0.44 


114 .... 


IO 


10 


Tub 


Oysters, shell . . 
Peaches 


36-42 
32-36 


.92 .... 


.... i mo. 


25 

5 


25 

4 


Sack 
* bu. basket 


Pears 


30-36 


.92 


.... 2 mo. 


5 


4 


* bu. basket 


Pork, fresh... .. 


30-32 


.50 1 0.30 


90 i mo. 


i 


* 


i Ib. 


Pork, cured. . . . 


40-45 






J 


i 


i Ib. 


Potatoes 


34-38 


.80 < 0.42 


105 6 mo. 


25 


25 


Barrel 2\ bu. 


Poultry 


15-20 


.80 0.40 


102 3 mo. 


i 


i 


i Ib. 


Sausage, fresh. . 


36-40 


.70 .... 




i 


J 


i Ib. 


Sausage, smoked 
Strawberries. . . 


40-45 
36-40 


.60 .... 
.92 .... 


.... short 


i 
* 


i 

* 


i Ib. 
i qt. box. 


Vegetables, bbl. 


36-40 


.91 ; 


.... 2 to 4 
weeks 


25 


25 


i barrel 


crate. 


36-40 


.91 .... 


.... 2 to 4 


12 


12 


i bu. crate 








weeks 








Watermelons. . . 


34-36 


.92 .... 




5 


5 


I melon 


Wines 


40-45 


.90 .... 




35 


35 


i barrel 



By use of Eq. (35) the amount of refrigeration to cool 
the goods and freeze them may be computed. It is well 



216 ELEMENTS OF REFRIGERATION 

to note that the time required to do this is an important 
factor. If the time is short the amount of refrigeration is 
large. This amount of refrigeration for this reason may be 
much larger than that required to care for the heat loss from 
the room. 



CHAPTER VI 
COLD STORAGE 

THE purpose of cold storage is to prevent the development 
of life which would cause decay of living tissue; it is also used 
to prevent the development of living .organisms. It is used 
not only for the storage of foodstuffs, but for the storage of 
furs, trees, flowers and other articles which require a low 
temperature for their proper keeping. 

The principal application of cold storage is to the storage 
of food products. In 1905 W. T. Robinson stated that there 
were over $200,000,000 worth of products stored, divided 
between (a) living substances, such as eggs and fruit, requir- 
ing a moderate temperature and (b) non-living, as meats, 
butter and cheese, requiring a low temperature. In 1909 
the value of goods passing through cold storage amounted to 
$2,585,000,000, ranging from $25,000,000 in fish to $1,500,000,- 
ooo in meats, the meat annually chilled alone amounting to 
20,000,000,000 Ibs. There were 160,000,000 cubic feet of stor- 
age space exclusive of breweries, packing houses, creameries 
and stores. 

These goods are stored for various lengths of time. Meats 
may be frozen and then stored for a long time. There is 
some improvement in quality at first and although with lengthy 
storage there is no deterioration in the meat, the flavor is lost 
and for that reason long holdings are not good. Poultry 
may be frozen and for a certain length of time there is an 
improvement in quality. Eggs may be held for long periods 
and except for a loss of weight there is no ill effect. Cheese 
improves as it ripens in cold storage but after ripening there 
is no improvement. Butter suffers slightly in taste on long 
storage. Apples and pears are improved by holding, as certain 

217 



218 ELEMENTS OF REFRIGERATION 

chemical changes take place, while strawberries and peaches 
lose their flavor rapidly. These various articles require special 
temperatures for their storage and hence there must be special 
rooms in warehouses for each article. 

The value of cold storage is to equalize the supply of food- 
stuffs and make it possible to have certain foods during the whole 
year. The consumers claim that goods are held until the off- 
season and then exorbitant prices are asked, while the cold- 
storage men claim that prices are reduced by the ample supply 
which exists in the off-season. Formerly one of the great 
evils of the business was the lengthy storage of articles for 
times of high prices, hence laws have been made in many States 
to correct the evils of cold storage of foodstuffs which have 
hampered the business and brought about other evils. The 
United States Government is planning a national cold-storage 
law to cover interstate business and business in the District 
of Columbia. 

The cold-storage bills define cold storage to be any recepta- 
cle where for periods longer than ten days food products are 
kept at 40 F. and under. There is usually a time limit for 
most substances; this varies from nine to twelve months. The 
materials stored must have the dates of receipt and delivery 
by the warehouse stamped on them and no restorage is per- 
mitted in some States. No cold-storage goods with dates 
erased may be sold. When eggs and butter are stored they 
must be sold as refrigerated articles and signs should state 
this. This refers to eggs after thirty days. In some States 
there are fines for the first two offenses and fine and imprison- 
ment for the third offense. An important feature covered by 
U. S. Senate Bill 136 was the requirement that no food could 
be placed in cold storage unless in a sanitary condition. The 
condition when received and previous history of an article to 
be stored is as important as the storage. The Senate bill 
prohibits the manipulation of cold storage goods to resemble 
fresh goods and frozen articles must be sold in that condition. 

An investigation by the U. S. Department of Agriculture 
showed that in three months the various percentages of stored 



COLD STORAGE 219 

goods delivered from storage in certain warehouses expressed 
as a percentage of goods received at the beginning of the 
period were as follows: 

Beef 71-2% 

Mutton. '. 28.8 

Pork 95.2 

Poultry. : 75 . 7 

Butter 40 . 2 

Eggs . 14-3 

Fish. . . 35 -5 

And in seven months the amounts used were: 

Beef 99 % 

Mutton - 99-3 

Pork - 99-9 

Poultry . 96 . i 

Butter - 88.4 

Eggs - 75-8 

Fish 64.9 

The average months of storage were as follows : 

ist Half Year. 2cl Half Year 
Months Months 

Beef 2.6 1.8 

Mutton 4-8 3-o 

Pork 0.8 i.o 

Poultry.' 2.6 2.4 

Butter - .- 4-5 4-Q 

Eggs 6.1 1.7 

Fish 6.8 

This investigation shows that goods do not remain in storage 
for a long time. 

The goods stored are handled in special ways and these will 
now be discussed together with certain data to be used in 
designing cold-storage warehouses. 



220 ELEMENTS OF REFRIGERATION 

Eggs. It has been stated that of the 3 billion dozen 
eggs produced in the United States yearly, 240 million dozen, 
or one-twelfth, are put into cold storage. Eggs are usually 
placed in cases containing 30 doz. These cases weigh about 
50 to 55 Ibs. and are usually stored in tiers five or six high 
with slats between cases to give a chance for air circulation 
and the removal of heat. These cases are 12X13X25 ins. 
and occupy 2\ cu.ft. of space. The eggs lose weight on storage, 
about 7% being lost in five or six months. If the air in the 
storeroom is too dry there is considerable loss of weight, while 
damp air will cause a fungous growth on the eggs. In many 
cold-storage warehouses there is no forced circulation, the ice 
on the pipes keeping the air a proper humidity. Should the 
air become too moist it may be dried by putting calcium 
chloride trays on top of the refrigerating coils and draining off 
the solution formed. This salt may be regained by evaporat- 
ing the water. 80% relative humidity has been found to give 
good results. 

The eggs are held at 30 or 31 F. and as they absorb odors 
they should be placed in rooms containing eggs only. They 
are placed in storage in April, May and June and are usually 
kept for about nine months. They have been kept for twenty- 
three months and except for a shrinkage of 25% they were 
not affected by storage. The cost of this storage is 10 cents 
per case for the first month and y| cents for subsequent months; 
40 to 45 cents would be the charge for the season. At 20 cents 
per dozen for the original eggs the item of 30 cents for the case, 
30 cents for freight, 40 cents for storage, 25 cents for interest 
and insurance, and 40 cents for buying, packing and grading 
makes the price per dozen 25.5 cents, leaving about 5 to 10 
cents per dozen margin for the owner, wholesaler and retailer. 
January is considered the end of the season. The eggs should 
not be washed when put in storage, as this spoils the appearance. 
At times they are candled' before storage, although this is not 
done regularly. Candling consists of holding an egg in front 
of an opening in a metal screen, Fig. 114, within which is an 
electric light (originally a candle). If the egg is not good 



COLD STORAGE 



221 



a dark center due to the thickening of the yolk will be noted. 
A good egg will appear practically uniform in texture, the light 
shining through the egg. Candlers become very expert and 
this work is done rapidly. Candling is often done when eggs 
are taken from cold storage. Good cracked eggs are broken 
open and the meat placed in cans holding about 50 Ibs., which 
are sealed and frozen. These are used by bakers. It is neces- 
sary to use these soon after thawing. 

Uncracked eggs are broken and canned to reduce the cost 




FIG. 114. Candling Box. 

of shipment. In Sedalia, Mo., a large plant is installed for 
cracking eggs. Here io| millions of eggs are cracked during 
a season under highly sanitary conditions to prevent con- 
tamination of the egg meat. The eggs are broken on a 
knife and the whites are separated from the yolks, the latter 
being well mixed before sealing the can. This holds 30 Ibs. 
The canned cracked eggs are frozen and shipped to bakers for 
consumption. It happens that the output of this plant is used 
by one baker alone. 

The shipment of eggs from China is increasing. The U. S. 



222 ELEMENTS OF REFRIGERATION 

Commerce reports from Shanghai, China, state that the ship- 
ment of eggs amounts to 800 to 1000 tons per month, i ton 
being 40 cu.ft. This is about 400,000 doz. per month. 

The storerooms for eggs and for all other storage should be 
kept clean and should be whitewashed about once a year. 

The whitewash used to sweeten rooms can be made with 
a bushel of lime slaked in boiling water with a peck of salt 
and enough water to make a thin paste. To each i2-qt. pail 
of this add a handful of Portland cement and a teaspoonf ul 
of ultramarine blue to overcome a yellow discoloration. To 
prevent dust on concrete floors, a solution of one part sodium 
silicate (water glass) of 40 Beaume and three to four parts of 
water has been applied to a dry floor after washing. 

Butter. This is held at 33 F., or it maybe frozen at a 
temperature of 15. It is considered that it loses flavor with 
time of storage, although instances are given where the buyer 
has not questioned the flavor of butter held for two years. 
It is better to store it in bulk than in small packages. The 
ordinary butter tub weighs 50 to 60 Ibs. and occupies about 
2 cu.ft. The tub must be sweet and clean and carefully closed. 
It is sometimes paraffined on the inside and sometimes lined 
with parchment paper. If the air is damp mould will form on 
the parchment. Butter will absorb odors and for that reason 
it should be placed alone in a room. The amount in storage in 
the United States in 1909 probably amounted to 100,000,000 
Ibs., while the total production of the country is about eighteen 
times this amount. 

"The temperature does not seem to help in preserving the 
flavor; On judging cold storage butter there was little differ- 
ence in: the total points of butter at 10 F. and 10 F., but 
butter at 10 F. was much better than butter at 32 F. It 
depends- on the kind of butter to a large extent. According 
to -Gray, high salt content and hermetical sealing are not 
advantageous in preserving flavor. A common method of 
storage is to chill the butter at first to o F. and then allow 
the temperature to rise to 16 or 20. Oleomargarine and 
such products may be held at about 20 F. 



COLD STORAGE 223 

The temperature carried is a question of economy; the 

cost of refrigeration is placed against the saving in value of 
flavor. The limit of time of storage is about eleven months. 
The house should be sweetened with whitewash and a wash- 
ing of roVo bichloride of mercury in water once a year. 

A mixture of ice and salt is sometimes used for the cooling 
of these rooms. Cooper reports a butter-freezing room in 
Kentucky where 1700 cu.ft. is held at io^ F. during August 
by the use of 507 Ibs. of ice and 109 Ibs. of salt per day. The 
egg room of 3560 cu.ft. is held at 30 F. by 790 Ibs. of ice and 
132 Ibs. of salt. At this place such a method was considered 
best with ice at $2.50 per ton and salt at $7.00 per ton. 

Cheese. Cheese weighs 60 Ibs. to the box and occupies 
about 2 cu.ft. It is stored at about 32 F., although 36 to 40 
is used. The U. S. Government tests were made at 31 to 32 F. 
Until it is thoroughly ripened this storage improves the cheese. 
Beyond that time it is not improved. The cold storage will 
check ripening and so keep the cheese. It is really to con- 
trol the ripening that refrigeration is used. To prevent loss 
of weight it is customary to coat the cheese with paraffin. 
It should not be frozen. 

Meat. Meat is improved by exposure to cold for a short 
time if kept at 25 to 28 F., but after about three weeks it 
gradually loses its flavor, although the meat is preserved. The 
fresh meat from the slaughter-house is placed in chilling rooms 
and it is cooled to the temperature of the main storehouse. 
In this way the chill room is equipped with excessive coil- 
cooling surface so as to remove the heat at the proper rate. 
Siebel states that 80 B.t.u. of refrigeration per twenty-four 
hours is required for every cubic foot of chill room. He 
states that i ft. of 2-in. direct-expansion pipe or 2 ft. of 2-in. 
brine pipe will care for 14 cu.ft. of chill room. If the meat 
is to be frozen for storage it is placed in a room at 10 F. and 
an allowance of 200 B.t.u. per twenty-four hours per cubic foot 
is made by Siebel and one-half the previous allowance per foot 
of pipe is used. This freezing is resorted to for shipment and 
for storage. This partially destroys the flavor. If thawed 



224 ELEMENTS OF REFRIGERATION 

slowly the flavor is not lost. The freezing should be done 
slowly and meat should not be stored in such large piles that 
the heat cannot be removed from the center. It should be 
held so that heat may be taken from all parts. If this is too 
rapid, the outer layer freezes before the inner part, and 
this leads to certain decay at the center of the meat. The 
amount of refrigeration may be computed from the specific 
heats and heats of fusion given in Chapter Vwhen the weights 
are known. The weight will vary, but the following averages 
may be used: 

Beef (two halves) 75 lbs - 

Calves 9 

Sheep 75 

Hogs 250 

The time of cold storage of meat may be at least six months 
if there is no chance of thawing. 

Poultry. The storage of poultry has been a practice for 
some years. The poultry is frozen and kept in this condition. 
Dr. M. E. Pennington has investigated the matter of storage 
and care of poultry for shipment for the U. S. Government. 
She points out that the preparation of the fowl for storage is 
as important as storage itself. The chickens should be starved 
for twenty-four hours before killing fo remove the putrid matter 
in the intestines, then the blood should be removed from the 
tissues after killing. and the picking should be done without 
breaking the skin. This should be done dry and not after 
scalding the carcass. The carcass and especially the feet should 
be. cleaned and prompt storage after chilling should be resorted 
to. With care of this kind the poultry is good after three 
weeks even if not frozen. The chill room is held at from 33 
to 38 and the packing at from 30 to 32. Certain State laws 
allow ten months storage of poultry. This is accomplished 
by freezing. In all cases the entrails are undrawn from the 
carcass. The poultry is usually placed in small boxes or barrels. 
The packages should be small so that air can reach all parts. 
The boxes should not be piled until after the poultry is frozen. 



COLD STORAGE 225 

Milk. Milk, if free from the germs of fermentation, will keep 
indefinitely, but this condition is difficult to attain, and for that 
reason the growth of the germs is prevented by lowering the tem- 
perature. Of course the pasteurizing of the milk by warming 
it to a temperature of 180 F. will kill the bacteria and not 
scorch the milk. This is followed by rapid cooling. Milk 
should be cooled as soon as possible after being drawn from the 
cow. The temperature at which it is held is about 40 F., for 
if frozen there is a formation or separation of flocculent par- 
ticles of albumen or casein compounds which do not redissolve 
readily on thawing. Fat globules or lumps are formed also. 
The cooling of the milk is accomplished in special block-tin 
coolers arranged so that they may be thoroughly cleaned. The 
milk passes over the outside and the refrigerant on the inside. 
One of these coolers is shown in Fig. 115. The Creamery 
Package Co. allows 20 sq.ft. of surface in these coolers per 
1000 Ibs. of cream or milk per hour, making the cooler of 
1 1 or 2 -in. copper or steel tubes, tinned on the outside. The 
trough at top or bottom is made of tinned copper. Other 
coolers are made with a hollow screw, which rotates in the ripen- 
ing box, while the screw is furnished with a cooling solution. 
By having a hot supply in the screw the box acts as a pasteur- 
izer and on following this with a cool solution the milk is 
cooled and made uniform by the turning of the screw. 

Cream. In the storage of cream a low temperature is 
necessarily combined with clean storage vessels. This cream is 
used largely for butter-making and in many of the eight thou- 
sand creameries of the United States refrigeration is not 
employed, resulting in a poorer quality of butter, as cream is 
often held for some time by farmers before shipment to the 
creamery is made. The separation of the cream is carried on 
by the de Laval separator at the dairy or creamery and this 
may be done best at about 160 F. The cream after being 
cooled to 50 is stored and finally allowed to ripen at 70 F. 

Fish. Fish is usually frozen and coated with ice before ship- 
ment and storage. This method is highly developed in the 
Northwest, 1000 carloads of halibut being shipped yearly from 



226 ELEMENTS OF REFRIGERATION 




FlG. 115. Spiral Coil, Disc Coil and Tubular Cooler of Creamery Package Co. 



COLD STORAGE 227 

Vancouver. The fish are decapitated, cleaned, washed and 
placed in sharp freezers, the refrigerating coils acting as shelves. 
Certain of these rooms are equipped with two sets of eight 
shelves made up of i-in. extra heavy pipe 37 ft. long. These 
pipes are supplied with liquid ammonia for direct-expansion, 
and by keeping liquid in each of them the system is flooded. 
Here the fish remain for a day at 10 to 24 F. below zero and 
they are glazed with ice after freezing by dipping them in 
water. This ice retains the fish oil and keeps the flavor. 
After this operation they are wrapped in parchment paper and 
boxed for shipment at IQ F. 

Oysters are held in cold storage at 35 F. for some time. 
After opening, the oysters may be placed in a bucket and frozen 
solid. This is not advisable. 

Fruit. Fruits of all kinds are kept in cold storage, but the 
time in certain cases should not be long, since some of them 
lose flavor. 

Apples are usually stored in i\ bu. barrels weighing about 
150 Ibs. and occupying 5 cu.ft. of space. They are usually 
held at 30 to 35 F. for winter apples while the softer summer 
apples are held about 5 above these. In England 29 to 30 F. 
has been used. Apples seem to improve on cold storage; 
there is a transformation of some of the starch into sugar. 

Apples have been kept for months and even as long as two 
years. Care must be exercised in picking and packing. If 
carefully picked they keep for a considerable time. The ship- 
ment abroad is very extensive and the loss on cold storage 
apples is very slight, amounting to from about 25 cents to some- 
thing over a dollar per barrel. This business in 1910 amounted 
to over nine hundred thousand barrels, valued at mere than 
two million dollars. 

Pears aie improved by storage in a way similar to that for 
apples, but they are not usually kept so long. The temperature is 
about the same as that for apples or a little higher 30 to 36 F. 
These are usually placed in boxes of 40 Ibs. weight when full 
and are picked in an under-ripe condition. Bushel crates are 
sometimes used. Closed barrels are not advisable, as the heat 



228 ELEMENTS OF REFRIGERATION 

cannot be removed from the center fast enough. Wrappers 
of paper are advisable to protect the fruit from bruises and to 
keep the color bright. 

Peaches are kept for a few weeks only and are placed in boxes 
or crates weighing about 20 Ibs. They lose flavor if held long. 
The storage is for the purpose of transportation and to lengthen 
the season for selling. They are held at from 32 to 36 F. 
In shipping and storing these the boxes are placed on top of 
each other about five boxes high, and the fruit should be., cooled 
slowly and warmed slowly to prevent sweating. The fruit 
should be carefully picked and at times it is stored slightly 
under-ripe. 

Strawberries lose their flavor on storage and they are kept 
for only a short time. They are held at 40 F. to prevent 
ripening. Experiments have been made which show that these 
and other berries may be kept for four weeks. Huckleberries 
have been held at 20 F. for pie making. 

Plums may be kept for several weeks at 34 F. if firm and 
sound. 

Grapes. These may be shipped from the West with success. 
They are held at various temperatures. Some require 32 F. 
while with others 34 to 36 is used. They should be dry when 
stored. They may be held from one to two months. Seventy 
days have been recorded for storage in redwood sawdust. 

Oranges and lemons are important items in the commerce 
of California. This business amounted yearly in 1905 to over 
$25,000,000 or 30,000 car loads. These cars hold from 15,000 
to 30,000 Ibs. of fruit. The matter of storage has received close 
attention from the government as well as from private parties. 
Oranges are picked at convenient times from February to May 
and are usually shipped in crates 15X15X30 ins., weighing 
about 70 Ibs. These are placed on end in storage and usually 
in two layers. The -fruit must be carefully picked, as bruised 
fruit decays. They should be held in shipment at 32 to 50" F., 
and on account of the improper care the loss in shipment has 
amounted to over one million dollars per season. At 32 F. 
they may be stored three weeks to a month, but oranges are 



COLD STORAGE 229 

uncertain for this time. At times the storage is extended to 
three months. They give off large amounts of gas and require 
ventilation and if the air is too dry shrinkage occurs. 

Melons may be held for several weeks at 35 F. They 
must be carefully picked and selected for long storage. Usually 
the storage is for a short period. 

Bananas are usually picked green and are allowed to ripen 
gradually, the amount of ventilation determining the speed of 
ripening. At 34 they may be stored for some time, while at 
40 they gradually ripen. At 32 they are apt to turn black. 

Vegetables. Potatoes are held at 35 F. in bags or barrels 
and should be so stacked that air may reach them. This must 
not be dry air. Potatoes are figured at 60 Ibs. to the bushel. 
If in barrels there will be 5 cu.ft. to about 2\ bushels. The 
room should be dark. 

Tomatoes, if picked when just starting to redden, may be 
kept, for two months. They are usually crated after wrapping 
in tissue paper. They are held at 40. 

Onions are stored at about 34 for six months. These 
give out an odor and should be kept in a special room. They 
are placed in bags or barrels. 

Celery is held in crates of about 140 Ibs. These crates 
are about 24X24X30 ins. Celery is held at about 34 F. for 
three or four months. The seasons for production in different 
parts of the United States make it possible to get this at all 
times of the year. 

Cabbages are held at 35 F. These are stored in barrels 
or crates. Air circulation is necessary. 

Tobacco and cigars are held at 40 to 45 F. and will retain 
their flavor if kept in one condition. This low temperature 
prevents the development of insect life. 

Furs, Rugs and Clothing. The matter of the cold storage 
of goods subject to moths and other insects received attention 
during the last decade of the nineteenth century. In a paper 
by Dr. L. O. Howard it was stated that insects caused a loss in 
cereals of one hundred million dollars per year, and Mr. A. M. 
Reed conceived the idea of preventing a similar loss from insects 



230 



ELEMENTS OF REFRIGERATION 



acting on furs and woolen goods and experimented on the eggs 
of the moth and buffalo beetle and found that 50 or 55 F. 
was sufficient to prevent the hatching and 40 prevented the 



O D D D 

Temporary Storage 




a a a a 

Receiving Room 



Upper Floors 



First Floor 



Fl 



m 



FIG. 1 16. Small Store House. 

passing from the larval state. The miller and the beetle were 
killed at 32 F. and in the center of rugs they were killed in 
several weeks at temperatures of 32 to 40 F. This led to the 
establishment of cold storage for such articles held at 32 



COLD STORAGE 



231 



Florists hold lily of the valley pips, lily bulbs, feins, smilax 
and other plants or bulbs for months at low temperature. 
They also use the cold-storage room to control the growth of 
plants. 

The construction of cold-storage warehouses will vary 
with the peculiarities of the designer and the requirements of 
the ground selected for the plant. In general there is a receiv- 
ing room near a railroad track and a truck platform as well, 
close to the office for the receipt and delivery of goods. In some 
cases there is only a railroad platform, as goods are handled 



OB 


Upper 


Floors 


1st 


Floor 








2"Cork 








Cork 2 
Brick 2fj 
Cork 2' 


<- > 


12"Brick 
2>rk _> 


2"Cork 
<-24"Brick 
2"Cork 






< 


E 


> ^ < 


H 


) < 




( Receiving Platform 


B.R. Track 



FIG. 117. Plan of Large Store House. 

each way in carload lots. The receiving room is sufficiently 
large to hold several transhipping hand trucks and is connected 
by elevators to the various floors. In small houses the elevator 
shaft could pass through the center of the house opening into 
four rooms placed around it on each floor. The separate 
rooms are required to give the necessary number of rooms for 
the differing foodstuffs to be stored. This plan is shown 
in Fig. 116. In this way the elevator serves the four rooms. 
The attic under the roof is used for the condensers and storage 
and also serves as a heat insulator. The cork insulation on 
outside walls, certain inner walls, ceiling of first floor and on 
the upper ceiling is shown by heavy lines. 



232 



ELEMENTS OF REFRIGERATION 



For extensive plants, as those built in cities, the rooms 
may be larger and extend over the complete space cf one floor. 



' U'Cementaop finisV V_ ^ v ^ 




FIG. 1 18. Arctic Cooling Plant for Store. 

Such a plant is shown in Fig. 117'. The elevators in this plan 
serve two houses or two rooms of one house. A small storage 
room for a market is shown in Fig. 118 in which the various 



COLD STORAGE 



233 



details may be seen easily. The use of a brine tank or con- 
gealer makes it possible to shut down the machine at night 
after freezing the brine, this frozen brine furnishing the re- 
frigeration during that time. The various parts of the plant 




may be traced out. The congealer, Fig. 119, for wall coils, 
is sometimes used in larger rooms. 

Figs. 120, 121 and 122 show the arrangement of pipes, insu- 
lation room and machinery for small plants. In Figs. 118 and 
122 the air circulation may be followed. 



COLD STORAGE 



235 




236 



ELEMENTS OF REFRIGERATION 



The various arrangements of piping are shown in Fig. 123. 
In Fig. A, the coil is carried on the ceiling while in B it is 
carried on' the walls. When the coils are carried on the ceil- 
ing, moisture is likely to drop from the pipes on the goods 
below, and then the ceiling coils are placed over aisles or else 
they are placed in lofts as in D, E and F. In these lofts the 




FIG. 122. Small Store House of Remington Machine Co. 

floor is placed under the pipes to catch the drip and take it to 
a gutter, but there is an open space at the center to allow the 
cold air to fall, while side partitions near the center or at the 
sides near the walls aid in circulation of air. The wall coils 
are better in most cases, although there is danger of cooling 
the goods near the coils too much. In Figs. C and E there 
are brine tanks or congealers used in the rooms and the cool- 
ing of this large amount of brine to a low temperature or the 



COLD STORAGE 



237 



freezing of the brine permits the compressor to be shut down. 
Figs. A , B and D may be used with brine or direct expansion 








E F 

FIG. 123. Arrangement of Piping as Shown by Creamery Package Co. 

of ammonia. C and E are for direct expansion. For inter- 
mittent operation when brine is to be circulated, Fig. F is 
employed, the tank supplying the refrigeration on shutting 



238 



ELEMENTS OF REFRIGERATION 



down the plant. Such an arrangement is used when ammonia 
piping is objectionable. 

In constructing the elevator and well the elevator car has 
a ceiling as well as a floor and these are made as air tight as 
possible, so that when the refrigerator door at any floor is open 
there is no danger of air circulation from the warmer air out- 
side. The floor and ceiling of the car have rubber or felt filling 




FIG. 124. Elevator. 

strips, closing off the air space so that the heat loss on opening 
the door is a minimum. Fig. 124 shows this. 

^Fig.^ 125 gives a section through a storehouse for meats 
while Fig. 126 illustrates a section of a ship containing refriger- 
ated space. 'The arrangement of the cooling coils for cir- 
culation and drip is to be noted as well as the air loft under 
thereof as in Fig. 116. 

The number of rooms used in hotels varies with the hotel. 



COLD STORAGE 



239 




240 



ELEMENTS OF REFRIGERATION 




COLD STORAGE 



241 



Thus in the Blackstone Hotel of Chicago the following cold- 
storage rooms are found: 



Basement. 
Vegetable box n' s"Xio' ^"Xj' 
Fruit box 13' 9"X 10' 3"X 7' 
Meat box 14' 4"X8' 4"X 7' 
Bouillon box 7' 2 ; 'X8' 4"X7' 
Game box 5' 6"X8'4"X7' 
Egg box 4'6"X4' 2"X7' 
Butter box 4'6"X3' 2"X7' 
Milk box g'Xs' 2"X7' 
Cheese box 5'4"X3'3"X7' 
Oyster box 12' o"X6' 8"X7' 
Fish box 6'X6'8"X7' 
Fine wines box 7' 9"X4' 7"X7' 
Ice-cream box 10' o"X 10' o"X 10' 
Sharp freezerbox, 5' o"X 10' o"X 10' o" 
Draft beer box 9' o"X9' o"X6' 

Banquet Hall. 
Refrigerator : i4'X4'X9' 


Kitchen. 
Poultry box 
Fish box 


9'Xs'Xs' 10' 

X2'8"X2' 10" 

X3'4"X3' i" 
3"X4'X3' 10" 
VX4^X9' 


Lobster box 
Bouillon box 2' 8" 
Cold plate box 13' 
Cold plate box n' 
Cold meat box 
Sandwich box 


General kitchen 9'Xi3'X9' 
Oyster box i6'X4'X9' 
Pantry 6'X6'X9' 
Freezers for ices 6'X3'X?' 
Fruit and salad box 5'X3'X9' 
Milk box 4'X3'X3' 
Baker's box 8'X8'X8' 
Ice cream n' 6"X3' 6"X3' 


Short order 5 
Cook's box 


X3 4 X3 10" 

. ...i6'X4'X9' 



In addition to the above there are some boxes on the dining- 
room floor and the club floor. 

To do this work and to cool the dining rooms and certain 
places as well as to make some ice requires a 5o-ton machine 
and a 75-ton machine. 

In Fig. 127 a direct expansion CC>2 plant for a brewery is 
shown. Each storehouse is cooled by large direct-expansion 
coils. In the air loft above the fermenting tanks is noted 
a sweet-water cooler. The water which is cooled in this tank 
is passed through coils in the fermenting vats to remove the 
heat of feimentation and control this process. The large 
vats are used for proper aging before storage in the chip casks 
on the lower floor. The path of the gas from the two compres- 
sors through the condenser and piping and the construction 
of the walls should be examined. 

The refrigeration for storage of food may be done with 
natural ice and salt as was mentioned in Chapter II. In 
Minnesota a wholesale and retail market refrigerates 40,000 
cu.ft. of space with 553 tons of ice at $1.65 per ton and 67 tons 
of salt at $7.00 per ton, holding the room at 15 F. 



ELEMENTS OF REFRIGERATION 




COLD STORAGE 



243 



The walls of these houses and the floors are constructed 
in various ways. Thus at the Boston Terminal Refrigerating 
Co. plant, a building 156 by 100 ft. with seven floors and a 
ventilating loft, the walls were made of 4-in. vitrified water- 
proof brick, 8 ins. of hollow tile and two 2-in. thicknesses of 
Nonpareil cork held in place by asphalt cement. This wall does 
not carry any of the floor load. The building is of reinforced 
concrete and the only floors insulated for heat are the base- 
ment floor, third floor, and eighth floor. These floors are 
insulated with two thicknesses of 2 in. or 2- and 3 -in. thick- 
nesses of cork board with an asphalt wearing surface. This 
construction forms a fireproof building. A suggestion has been 
made to use two 4-in. tiles with a third tile 8-ins. from the outer 
ones with a cork filling between the outer wall for a fireproof 
building. This wall carries no weight. The columns carrying 
the weight are of reinforced concrete. In this system the par- 
titions are made of two 4-in. tiles with a 6- or 8-in. cork fill. 
The floors are of 6 ins. reinforced concrete, 2 or 4 ins. of cork 
and asphalt on top. The doors are 
covered with iron. 

In an apple-storage warehouse the 
walls were made of 2X6 hemlock 
boards laid flat, as are used in grain 
elevators, and faced on one side with 
4 ins. of brick. Fig. 128. Such a 
construction should give good results. 
The installation cares for 15 cu.ft. of 
space with i lin.ft. of 2 ins. direct 
expansion. 

In large plants the insulation is 
such that the heat loss is 1.8 B.t.u. 
to 0.6 B.t.u. per square foot per 
hour or for values of K of 0.03 to 
o.oi. 

Any of the forms of Chapter VI may be used for the insula- 
tion and for any form of construction the value of K may be 
computed as shown. 




FIG. 128. Grain Bin Construc- 
tion for Apple Storage. 



244 ELEMENTS OF REFRIGERATION 

Partitions between rooms may be made of two 2 -in. cork 
boards faced with 4-in. tile or with cement plaster. 

The temperature of the rooms should receive consider- 
able thought in determining what should be used. The highest 
possible temperature for good storage should be used. Some 
storage men claim that zero rooms cost from 50 to 75% more 
to operate than rooms at 30 F. The proper selection may 
make a success from what has been a failure. The table on 
p. 215 gives the temperatures required for different articles. 

After the temperature is fixed, the amount of insulation 
should be figured so as to make the annual expense a minimum. 
The annual expense is made up of interest, depreciation, taxes, 
insurance on insulation, value of space occupied and insurance 
on the stored materials and the cost of absorbing the heat 
leaking through the insulation. If the thickness is increased 
and the kind of insulation improved, the first items will increase, 
but the cost of absorption will be decreased and if the sum of 
these is .decreased then the improvement pays. If the sum 
is increased a poorer insulation would give better results, the 
increase due to the cost of insulation not making up for the 
saving in refrigeration. By plotting these costs for different 
thicknesses the best thickness may be found. 

In estimating these items the charge iri insurance due to 
various constructions must be considered. Thus in frame 
buildings, according to J. H. Stone, the insurance is i% while 
in fireproof buildings it is only % and |% for semi-fireproof 
buildings. This refers to goods as well as buildings and this 
should be considered in fixing the cost. The depreciation on 
insulation is taken by him at 4% in good construction and 
at 8% in wooden buildings. The cost of insulating material 
is given by Stone as 27 cents per square foot for 2 B.t.u. per 
square foot per twenty-four hours per degree difference. 

The cooling is accomplished by coils or by air circulation. 
The coils, as shown in Fig. 123, are either brine coils or direct- 
expansion coils. In some plants brine is thought to be neces- 
sary. In present-day work especially with welded pipes 
ammonia is safe and is used. 



COLD STORAGE 



245 



The direct-expansion system requires less difference in pres- 
sure between suction and discharge main, giving a more efficient 
plant. The brine system, however, in addition to the question- 
able advantage of safety in case of rupture does possess certain 







E F 

FIG. 129. Arrangements of Direct and Indirect Refrigeration. 

advantages. If a large amount of brine is cooled during the day 
this may be used when the compressor is shut down and, more- 
over, the cost of the expensive ammonia to fill the system is 
eliminated. To increase the storage capacity it is even pos- 
sible to freeze the brine, removing about 150 B.t.u. per pound 



246 ELEMENTS OF REFRIGERATION 

of brine. These advantages are worthy of consideration, 
although the lower back pressure on the compressor when 
brine is used to care for the double transfer of heat makes 
the advisability of its use a matter hard to determine. 

The coils, of whatever kind they may be, are best placed on 
the side walls near the ceiling, as ceiling coils are apt to collect 
and drop moisture. If the room is over 25 ft. wide a ceiling 
coil must be used in addition to the side coils. This should 
be placed over aisles. There should be ample coil surface. Of 
course it is necessary to keep certain goods at the proper dis- 
tance from side coils to prevent freezing. The use of cross 
aisles and the arrangement of goods in tiers to aid in circu- 
lation of the air of the room are advisable. The cross-sections 
of rooms are shown in Fig. 129 in which the circulation is 
indicated. The use of the aisles to separate goods of differ- 
ent owners is advisable. The use of partitions of tin around 
the pipes to catch drip and to cause a definite current is shown 
in E and F. 

The air for the storage room should be cleaned and dried 
before allowing it to enter. Ventilation should be accomplished 
by the air of the room rather than by outside dirty air. In 
many storehouses such as the 4,300,000 cu.ft. house of the 
Merchants' Refrigerating Co. of Jersey City, there is no circula- 
tion provided. The circulation is all brought about by large 
pipe coils placed over the aisles and not at one place. 

In the indirect system of cooling by air circulation air is 
cooled and blown into the room. The coils may be placed in 
ducts in ceiling or as is generally the case they may be placed in a 
large space called a bunker room and the air blown across these 
is carried to ducts and flues leading to the various floors. 
The distribution of air in the storage room is difficult. In 
some cases it is distributed through numerous small holes in 
the ceiling and the warmed air is removed through holes in 
the floor. In this way an even distribution over the whole 
room is obtained, although other methods are used. The air 
may be recirculated if there are no odors. This is one of 
the objections to the indirect system. Smoke or odors from 



COLD STORAGE 



247 



Fig. 



one room may contaminate the stored goods in another. 
129 illustrates warehouse rooms using forced-air systems. 

The bunker room is shown in Fig. 130. In this, brine or 
a volatile liquid is passed through the coils and abstracts heat 
from the air, which is blown across the pipes. The moisture 




Dehydrator 



FIG. 130. Bunker Room. 



removed from the air freezes on the outside of the pipes, but 
by circulating brine occasionally over the pipes this frost is 
removed or warm brine may be turned in when the air is 
shut off. 

In some houses the radiation surface is increased by the 




FIG. 131. Radiation Discs. 

use of split discs added to the outside of direct-expansion pipes, 
Fig. 131. These are not used often at present although in 
former times they were used extensively. 

The air is driven by a fan blower. Forms of blowers 
arc shown in Fig. 132. The size of the fan and the 
power to drive the fan are fixed alter the sizes of ducts 



248 



ELEMENTS OF REFRIGERATION 



have been computed. The duct sizes are fixed by the allow- 
able velocities of the air. The velocities to be used are as 
follows: 

Main ducts 1200 ft. per min. = 20 ft. per sec. 

Branch ducts 800 " =13 " 

Register faces 300 =5 ' ' 







Buffalo Planoidal Fan. 





Sturtevant Multivane. American Sirocco. 

FIG. 132. Fan Blowers. 

The quantity of air is fixed by finding the quantity of heat 
to be removed and the allowable rise in temperature in the 
air. If Q is the heat entering the room per hour, /, is the 
temperature of the room and to is a temperature to which the 



COLD STORAGE 249 

air can be cooled in the bunker room, the volume of air per 
hour V is given by 

== 2^ _ 2_ 



_ 

0.24 (/,-/,) 0.02 (/,-/i) 

V = cubic feet of air per hour; 

Q = heat removed per hour in B.t.u. figured from methods 

of Chapter V; 

k= temperature at outlet from hunker in deg. F. ; 
/, = temperature of room in deg. F.; 
v = volume of i Ib. of air 
= 12 cu.ft. approximately. 

If w equals the velocity in feet per second in the duct or 
register the area F in square feet is given by 

(2) 



3000W 

The sizes of the ducts are found and then the hydraulic 
radius of each duct is computed. This is equal to the cross - 
section of the duct divided by the perimeter. If b and d are the 
dimensions of the duct in feet and RI is the hydraulic radius 
in feet the following are true: 

bd = F, ....... (3) 

. (4) 



2(b+d) 

The friction loss in pressure along a straight pipe of L ft. 
length is given in feet of air pressure by 

# = o.o2X-^^-. (5) 

For bends of radius equal to 2b, the loss is 

#=0.15- (6) 



250 ELEMENTS OF REFRIGERATION 

In grills the loss is given by 

H = o.S^ (7) 

2 

At gradual changes of section there is no loss. 
For loss in the bunkers with staggered cooling coils the loss 
of head may be taken as 

tf=o 4 - . ..'... (8) 

2 

for each coil or line of pipe over which the air must travel. 

If now in any line the sum of the various losses is taken, 
the total loss may be found. This is the static pressure to be 
produced by the fan and in some fans this may be taken as 

about three times the velocity pressure, . The sum of these 

two pressures is called the dynamic pressure, and the ratio of 
this to the static pressure is usually given in catalogs of fan 
makers. The static pressure varies from 70 to 90% of the 
dynamic pressure in various forms. The dynamic pressure is 
the one listed in most catalogs. Having the dynamic pressure 
in feet of air found by dividing the static pressure by 0.75, this 
may be .changed to ounces per square inch by dividing by 1 20 
for air at 70 or by no for air at 20 F. If pressure in inches 
of water is desired this pressure in ounces per square inch is 
divided by 1.73. 

The data for three types of fan are given in the table on 
p. 251 for the points of best efficiency: 

From this table the fan must be picked out to deliver the 
desired volume, at a given dynamic pressure. 

Since in general the pressure is not a tabular pressure, the 
equivalent volume must be found for a tabular pressure. 
When a fan is run at the same point of its efficiency curve, 
the pressure varies as the square of the velocity or as the square 
of the number of revolutions; the quantity of discharge varies 
as the velocity or number of revolutions and the power which 



COLD STORAGE 



251 



FAN DATA 



SIROCCO FAN. 
Velocity Press. =0.288 
Dyn. Press. 


BUFFALO CONOIDAL FAN. 
Velocity Press. =0.225 
Dyn. Press. 


STURTEVANT MULTIVANE 
FAN. 
Velocity Press. =0.10 
Dyn. Press. 


Diam. 
of 
Fan 
Wheel. 




Dynamic 
Press. 


i 

& 




Dynamic 
Press. 


1 

f. 




Dynamic 
Press. 


ioz. 


I OZ. 


ioz. 


2 OZ. 


ioz. 


I OZ. 




Cu.ft. 
R.P.M. 
B.H.P. 


38 
2,290 
0.005 


77 
4,58o 
0.037 


30 


Cu. ft. 
R.P.M. 
B.H.P. 


1,720 
632 
0.39 


3,435 
1.255 
3. ii 


3 


Cu.ft. 
R.P.M. 
B.H.P. 


1,000 
502 
0.12 


2,000 
1,003 

I.O 


4i 


Cu.ft. 
R.P.M. 
B.H.P. 


87 
15,24 

O. 01 I 


175 
4,58o 
0.084 


35 
40 
45 
50 
60 
70 


Cu.ft. 
R.P.M. 
B.H.P. 


2,340 
545 
0.53 


4.675 
1,085 
4-23 


4 
5 


Cu.ft. 
R.P.M. 
B.H.P. 


1,448 
4 l8 
0.19 


2.895 
835 

i.S 


6 


Cu.ft. 
R.P.M. 
B.H.P. 


J55 
i. I4S 
o. 018 


3io 
2,290 
0.147 


Cu.ft. 
R.P.M. 
B.H.P. 


3,060 
482 
0.69 


6,100 
960 
5.52 


Cu.ft. 
R.P.M. 
B.H.P. 


1,950 
359 
0.25 


3.900 

717 

2.O 

5,130 
627 
2.6 


9 


Cu.ft. 
R.P.M. 
B.H.P. 


350 
762 
0.042 


700 
1,524 
0.333 


Cu.ft. 
R.P.M. 
B.H.P. 


3,890 

422 
0.88 


7,76o 
845 
7-03 


6 


Cu.ft. 
R.P.M. 
B.H.P. 


2.565 
3U 
0-33 


12 


Cu.ft. 
R.P.M. 
B.H.P. 


625 
572 
0.074 


1,250 
1,145 
0.588 


Cu.ft. 
R.P.M. 
B.H.P. 


4,780 
378 
1.09 


9.56o 
753 
8.67 


7 
8 


Cu.ft. 
R.P.M. 
B.H.P. 


4,000 
251 
0.5 


8,000 
Soi 
4.0 


18 


Cu.ft. 
R.P.M. 
B.H.P. 


1,410 
381 
0.167 


2.820 
762 
1.33 


Cu.ft. 
R.P.M. 
B.H.P. 


6,875 
318 
i-SS 


13,650 
636 
12.38 


Cu.ft. 
R.P.M. 
B.H.P. 


5,800 
218 
0.72 


1 1, 600 
435 
5.8 

15.700 
359 

7-9 


\ 24 


Cu.ft. 
R.P.M. 
B.H.P. 


2,500 
286 
0.296 


5,000 
572 
2.35 


Cu.ft 
R.P.M. 
B.H.P. 


9,450 
272 
2.14 


18,750 
542 
17.00 


9 


Cu.ft. 
R.P.M. 
B.H.P. 


7,850 
1 80 
0.99 


> 30 


Cu.ft 
R.P.\1. 
B.H.P. 


3.910 
228 
0.460 


7.820 
456 
3-68 


90 


Cu.ft. 
R.P.M. 
B.H.P. 


I5,6oo 

2IO 

3-54 


31,200 

419 
28.3 


IO 

ii 


Cu.ft. 
R.P.M. 
B.H.P. 


10,300 
157 
1 . 25 


20,600 
314 
IO. O 


> 36 


Cu.ft. 
R.P.M. 
B.H.P. 


5,650 
190 
0.655 


11,300 
38i 
5.30 


no 


Cu.ft. 
R.P.M. 
B.H.P. 


23,100 

172 
5.24 


45,700 

343 
41.4 


Cu.ft. 
R.P.M. 
B.H.P. 


12,925 
139 
1.64 


25,850 

278 

13. r 


5 48 


Cu.ft. 
R.P.M. 
B.H.P. 


10,000 

143 

1.18 


20,000 

286 
9.40 


130 


Cu.ft. 
R.P.M. 
B.H.P. 


32,400 
146 
7-34 


64,700 
291 
58.6 


12 


Cu.ft. 
R.P.M. 
B.H.P. 


16,000 
126 

2.02 


32,000 
251 
16.2 


3 60 


Cu.ft. 
R.P.M. 
BH.P. 


15,650 
114 
1.84 


31,300 

228 
14.7 


150 


Cu.ft. 
R.P.M. 
B.H.P. 


43,000 
127 
9.80 


86,000 
253 
78.0 


Cu.ft. 
R.P.M. 
B.H.P. 


19,400 
114 

2-44 


38,800 

2.28 
19-5 


2 72 


Cu.ft. 
R.P.M. 
B.H.P. 


22,600 
95 
2.66 


45.200 
190 

21 .2 


170 


Cu.ft. 
R.P M. 
B.H.P. 


55,500 

112 
12.55 


110,000 
235 
88.8 


14 


Cu.ft. 
R.P.M. 
B.H.P. 


23,200 
105 
2.94 


46,400 
209 
23-5 


4 87 


Cu.ft. 
R.P.M. 
B.H.P. 


30,800 
81 
3.6i 


6l,600 

163 
28. g 


i<>< 

200 


Cu.ft. 
R.P.M. 
B.H.P. 


69,OOO 
IOO 

15.61 


I37,8oo 
199 
124.8 


IS 
17 


Cu.ft. 
R.P.M. 
B.H.P. 


27,200 
97 
3-44 


54,400 
194 
27 50 


5 90 


Cu.ft. 
R.P.M. 
B.H.P. 


35,250 
76 
4.14 


70,500 
152 
33-1 


Cu.ft. 
R.P.M. 
B.H.P. 


76,600 

94 
17-35 


152,500 
188 
138.0 


Cu.ft. 
R.P.M. 
B.H.P. 


36.150 
84 
4.42 


72,300 
1 68 
35-4 



252 ELEMENTS OF REFRIGERATION 

varies as the product of quantity and pressure will vary as the 
cube of the number of revolutions. Hence 

..N e T7 IP~t , x 

Ve=Va^ = V a +hr C$0 



V e = equivalent volume discharged at speed N e revolutions 

per minute ; 

V a = actual volume discharged at speed N a ', 
N e = revolutions per minute to give total dynamic pressure 

Pi', 

N a = revolutions to give pressure P a ; 
P t - tabular pressure ; 
P a = actual pressure. 

Having V e the fan may be selected and then N a may be 
found to give the proper pressure and quantity. 



The power to drive this fan is given by 

HP a = HpL^; .......... (n) 

V e^t 

HP a = actual horse-power to drive fan; 
HP t = tabular horse-power to drive fan. 

If the relation between static pressure and velocity pres- 
sure is changed from that used, these values are changed, and 
although the tables may be used to get equivalent quantities, 
there is little use in giving the method of doing this, as the fan 
would then be working inefficiently. 

The fan and its power to be used are now known and the 
dimensions may be found in the tables on pp. 253 and 254. 



COLD STORAGE 



253 




i 

1 ix 

'^- H 




FIG. A. Fan Dimensions. 



DIMENSIONS OF SIROCCO FAN IN INCHES 



Size. 


A 


B 


C 


D 


E I F 


G 


H 


I 


J 


K 


X O 


P 


7 


28- 


asi 


40 


42 


36 I 31* 


2 7* 


26* 


23* 


28 


44 


8 20 


31* 


8 


32 


28? 


45 1 


48 


40* i 36 . 


3i 


2 9 


25! 


32 


5 C 


9 22 


35i 


9 


36 


32! 


Sit 


54 


45s ' 40 


34* 


34 


3of 


36 


56 


9 


24 


40 


10 


40 


36 


57* 


60 


5* 44* 


38 


37 


33i 


40 


62 


10 


26 


44 


ft 


44 


39* 


62! 


66 


55 48 


41* 


39* 


36 


44 


68 


IO 


28 


48 


12 


48 


43 


68J 


72 


59l 1 525 


45 


45 


4i| 


48 


74 


II 


30 


52 


13 


52 


46* 


74* 


78 


64* 57* 


49* 


48 


44i 


52 


80 


II 


32 


56 


14 


;5 


.SO* 


80 


84 


69 . 59? 


5i 


52 


47! 


S6 


86 


12 


34 


56 


15 


60 


54 


8 S I 


90 


73* 64* 


54* 


53 


491 


60 


92 


12 


36 


60 



DIMENSIONS OF BUFFALO CONOIDAL FAN IN INCHES 



Size. 


A 


B 


C 


D 


E 


F 


G 


H 


I 


K 


N 





P 


30 


ii 


10* 


i4f ' i 61 


i3f 


14 


12* 


12 


9* 


X7J 


3 


7 


isA 


35 


I2f 


I2i 


i7s i9l 


is! 


16 


I4l 


13 


10* 


20 


3 


8 


i?A 


40 


I4i 


14 


IQl 22f 


I7i 


18 


16 


14 


"I 


22f 


3 


8 


i8H 


45 


16* 


iSi 


22| 


25f 


2C| 


20 


I7i 


iSi 


"1 


25f 


4 


9 


20^ 


5 


i8| 


17* 


24* 


28 


22 


22 


19* 


i6i 


isi 


28* 


4 


9 


22^ 


60 


22 


21 


29* 


33! 


26| 


26 


23 


19* 16 


34i 


5 


ii 


26i 


70 


25f 


24* 


34* 


39* 


30* 


3 


26* 


22 


i8f 


39f 


6 


12 


30 


80 


29* 


28 


39* 


45i 


34f 


34* 


29i 


24* 


20| 


45* 


6 


H 


34i 


90 


33 


3i* 


44i 


5| 


38| 


38* 


32i 


27i 


22| 


5il 


7 


16 


38^ 


no 


40* 


38* 


54 


6i| 


47i 


47 


38! 


32i 


27* 


62* 


8 


20 


46J 


130 


47i ! 45* 


64 


73i 


55! 


55 


4Sf 


37* 


32i 


73* 


9 


24 


54 


15 


55 52* 


73f 


8 4 f 


64! 


64 


52| 


43 


37i 


8 4 f 


ii 


28 


6 3 i 


170 


62* i 59* 


8 3 1 


95i 


72f 


72 


58! 


49 


42* 


96 


13 


32 


7ol 


190 


69! 1 66* 


93* 


107 


81 


82 


66f 


54 


46| 


107 


15 


36 


82i 


200 


73* 


70 


98* 


112} 


85i 


86 


6 9 f 


56* 


48| 


II2f 


16 


38 


8 S i 



254 ELEMENTS OF REFRIGERATION 

DIMENSIONS OF STURTEVANT MULTIVANE FAN 



Size 


A 


B 


c 


D 


E 


F 


G 


H 


I 


J 


K 


M 


N 





P 


10 


40 


to* 


4S 


52* 


40< 3 


37* 


26* 


36* 


38* 


32f 


48| 


32* 


10* 


20 


66f 


ii 


45 


14* 


Scf 


581 


45* 


41* 


29* 


39 i 


4* 


36f 


S4l 


36i 


12 


22 


73t 


12 


40* 


S8* 


^ 


65* 


5*i 


46 


33 


43l 


46i 


4 of 


60^ 


4oi 


12 


24 


81* 


13 


S4? 


42 


6i3 


7*1 


S5f 


Si 


36 


46i 


5i 


44f 


66} 


44i 


13* 


28 


8c* 


14 


soil 


4Sf 


67* 


78f 


6of 


55 


39 


49s 


S4l 


481 


72f 


48i 


13* 


32 


Q6 


I"? 


6 4 4 


40* 


73* 


84* 


65* 


60 


43 


54* 


59f 


s*i 


78^ 


5^i 


14* 


36 


105 


16 


6Q* 


ssl 


78* 


01* 


70 


64 


45 


581 


64* 


56! 


85 


S6* 


14* 


42 


112} 


17 


74* 


57i 


84i 


97! 


74f 


68 


48 


62 


69! 


6ol 


9i 


60} 


14* 


48 


I20j 



The amount of coil surface used in the rooms of a store- 
house should be figured by the usual formula: 

(12) 



Q = amount of heat removed per hour in B.t.u.; 

.F = area of surface square feet; 

K = constant of transmission B.t.u. per square foot per 

hour per degree; 

=5 to 10 for brine or direct-expansion coils to air; 
ft; = mean temperature of brine or ammonia, deg. F.; 
t T = temperature of room; 
tr-t c =iotoi 5 F. 

The quantity Q is fixed by the heat entering through the 
walls and the heat gained by lights, motors, persons and goods 
stored. The heat from the walls and other causes is computed 
by methods of Chapter V. Thejieat given up by articles is 
given by 



(13) 



c specific heat; 

T a = temperature of articles before storing; 
TV = room temperature; 

//= latent heat of fusion; 
M = weight in pounds; 

h = hours to cool and freeze. 



COLD STORAGE 



255 



Before computing this, h and T must be assumed for any 
substance, h is fixed by the designer, and the temperature 
of the room is given in Chapter V. The time h may be taken 
as from six to twenty-four hours. In all cases it is better to 
chill slowly. By adding the various heat quantities the total 
is found. 

On account ot the ice formation over the pipe the value of 
K cannot be told exactly, and for that reason the usual method 
is to allow a number of cubic feet of space for each lineal foot 
2 -in. pipe for direct expansion or brine. 

In some cases i ft. of 2-in. brine pipe is allowed to 12 cu.ft. 
for room temperature of 30 F. while 6 cu.ft. only is used for 
temperatures of from 5 F. to 10 F. 

The following based on Levey's tables may be used for 
2-in. pipe and direct expansion in rooms with good insula- 
tion, say 1.5 to 2 B.t.u. per square foot per twenty-four hours. 





Cu.ft. Per Foot of 2-in. F 


pe. 




Room 


Small Rooms, 


Medium Rooms, ' Large Rooms, 


Limit of Length. 
Feet. 


Temp. 


1000 Cu.ft. 


5000 Cu.ft. 


10,000 Cu.ft. 






Brine. 


Dir. Ex. 


Brine. 


Dir. Ex. 


Brine. 


Dir. Ex. 


Brine. 


Dir. Ex. 





I 


I 


2 


2 


3 


3 


100 


20OO 


10 


4 


5 


6 


8 


8 


12 


175 


20OO 


20 


6 


8 


10 


13 


13 


19 


225 


2OOO 


30 


8 


ii 


14 


17 


I? 


25 


275 


2OOO 


36 


10 


14 


16 


20 


20 


30 


3 00 


2OOO 



The length of the brine coil is limited by the amount of brine 
which may be cooled and the velocity of the brine, while with 
direct expansion it is merely a matter of the ammonia which 
may pass through. The length of the pipes should change with 
various diameters, since the surface varies as the diameter, while 
the quantity of brine or ammonia varies as the square of the 
diameter. The brine coils, however, are not varied in length, 
as the diameter is changed while the direct expansion-coils vary 
as the diameter, a i-in. coil having 1000 ft. as its limit of length. 
The cubic feet of space cooled per foot of length will vary 
as the diameter of the pipe. 



256 ELEMENTS OF REFRIGERATION 

The allowances made by Louis M. Schmidt are as follows: 
DIRECT-EXPANSION PIPING 

Freezing and brine tanks. ... 50 sq.ft. per ton of refrigeration. 

it it a 

Brine coolers. 10 

Freezing chambers 350 sq.ft. per 1000 cu.ft. 

Storage rooms 35 

BRINE PIPING 

Freezing chambers 500 sq.ft. per 1000 cu.ft. 

Storage rooms 50 

Bunker rooms 20 

Skating rinks 0.8 sq.ft. per sq.ft. of ice surface. 

These two sets of tables are practical rules for determining 
the amount of surface. The better method is to use the 
formulae of Chapter V and from them compute the heat lost 
and the pipe surface to care for the installation, using these 
tables as checks. 

E. H. Peterson in Ice and Refrigeration for November, 
1915, gives curves showing data for refrigeration of rooms 
of storehouses. For rooms at zero degrees his curve is to be 
given by the following equation: 

Cubic feet per ton of refrigeration -iooo/ cu ' ft room V 

V 5000, / 

Increase this by 80% for 10 F., 150% for 20 F., 250% 
for 30 and 333% for 40. 

One ton will care for 30x30 cu.ft. on an average, and noo 
sq.ft. of insulated surface. 

If it is desired to find F for the coil surface in a bunker, the 
quantity K will depend on the velocity of the air over the pipes. 
This is given by 

K = 2.2Vw (for wet pipes and wet vapor) 1 
K = i + 1 -3 v/ w (for dry pipes and wet vapor) J ' 
w= velocity of air in feet per second; 
ir is then equal to the mean temperature of the air. 



COLD STORAGE , 257 

The necessary length of pipe is then found and arranged 
as in Fig. 130, which shows a bunker for air cooling. 

It has been found by Sibley that ice formation on the pipe 
does not cut down the heat transfer, but aids it. An inch of 
ice in a brine tank coil serves to increase the transfer from a 
if-in. pipe to about four times its previous value, while 2 ins. 
increases it twelve times. The ordinary allowance of 120 to 
150 lin.ft. of if -in. pipe of expansion coil in a brine tank per 
ton of capacity is detreased by him to 40 ft. when ice is allowed 
to form on the pipes. For ice making this ordinary allow- 
ance is doubled to from 240 to 300 lin.ft. Sibley states that 
when ice can form around the expansion coils in the brine 
tank the rate of transfer is increased as stated above. 

The weight of ammonia per hour for a room or plant is given 
by 

^=M, -. (is) 



Q = heat in B.t.u. per hour; 
M a = weight of ammonia per hour; 
i\ =heat content at expansion pressure leaving coils; 
z' 4 = heat content leaving condenser. 

The lines carrying liquid ammonia should be of such a 
size that the velocity of the liquid is not over 4 ft. per second. 

The return lines should be such that the vapor returning 
is not moving faster than 50 to 100 ft. per second. 

These lines may be figured from drop in pressure using 
the steam formula: 



P= pressure drop in pounds per square inch in length L; 
L = length in feet; 
D = weight of i cu.ft.; 
d = diameter in inches; 
M= weight in pounds per minute. 

From this a drop may be assumed and d found or with a 
given d, P may be found. 



258 



ELEMENTS OF REFRIGERATION 



Brine is formed by allowing water to flow over calcium 
chloride or sodium chloride. This is best done by having a 
box or tank into which the brine is pumped and allowed to 
flow over lumps of the chloride, and after dissolving some of the 
salt it is allowed to pass out through the bottom of the tank. 
The density of the brine is fixed by the temperature at which 
it is desired to carry the brine. In most cases of closed brine 
systems it is necessary to keep the brine from freezing, although 
in congealing tanks it is desired that the brine freeze. The 
densities and temperatures of freezing are given as follows: 

FREEZING TEMPERATURE OF SALT SOLUTIONS 



Dens't ofcal /S 




062 


i 085 










cium chloride I Deg. Beaume at 64. . 


S.o 


8.6 


II. 4 


U.7 


IS. 9 


17.9 


19.7 


Density of so- j Sp.gr 


1 .022 


1.044 


i .067 


i .091 


I. 117 


1.142 


1.168 


dium chloride \ Deg. Beaume at 64 ,. 


3.0 


6.0 


9-0 


12. O 


15-2 


18.0 


20.9 


Temperature of freezing, deg- 


28 


24 


20 


16 


12 


8 


4 


Density of cal- / Sp.gr 


1.165 


1. 174 


1.186 


I. 197 


1.207 


1.216 


cium chloride I Deg. Beaume at 64. . 


20.7 


21.7 


23.0 


24.1 


25-2 


26.1 


Density of so- 1 Sp.gr 
dium chloride \ Deg. Beaumd at 64. . 


I -193 
23.5 












Temperature of freezing, deg 


O 


-4 


-8 


12 


-16 


-20 



The specific heat of brine varies with the density and the 
specific gravity. The latest data on this calcium chloride 
brine are given by Dickinson, Mueller, and George in the bulle- 
tins of the Bureau of Standards, U. S. Dept. of Interior, Vol. 6 r 
No. 3, or Reprint No. 135. In this the specific heat of brine 
at o C. is given by 



...... (17) 

3 = specific heat in B.t.u. per pound per degree; 
D = specific gravity of solution at o C. compared with 
water at max. density. 

For changes in temperature from o C. the value of 3 is 
decreased approximately 0.0008 for each degree centigrade 
below o C. 

The specific heat of sodium chloride is taken as 0.78 for 
1.2 sp.gr., 0.86 for i.i sp.gr., 0.94 for 1.05 and 0.98 for 1.02 



COLD STORAGE 259 

sp.gr. Having the amount of heat per hour required for a plant 
or room, the amount of brine required per hour is given by 



i ); ...... (18) 

() = heat in B.t.u. per hour; 
M 8 = weight of brine per hour; 

a m = mean specific heat at temp. ^i-' 

2 

to = temperature of brine at outlet = temp, of room 10 F.; 
t t = temperature of brine at inlet = ^-5 to 8. 

The length of pipe in one coil is such that this heat of the 
brine is given up in the length. Thus 






The kind of brine to use depends on the engineer. Some 
feel that calcium chloride will not corrode nor rust the iron as fast 
as the sodium chloride; neither should corrode the piping. On 
account of the impurities in the salt, brine may corrode the iron. 
If there is any acid in the brine, corrosion may occur. If there 
are dissimilar metals in the system, these will set up galvanic 
action and thus corrosion. Stray electric currents may also 
start corrosion. In the system there should be no brass pumps 
if the mains are of iron or steel. It is well to keep the brine 
alkaline by the addition of lime or dilute caustic soda. The 
calcium chloride permits of a lower temperature of brine for a 
given concentration and for that reason it may be employed. 

The brine is usually forced through the system by pumps 
of the direct-acting type, although centrifugal pumps are 
employed at times. The direct-acting pumps should be of 
such a displacement that they will deliver their full capacity 
in cubic feet at 45 cycles per minute. 

After the quantity of brine required per hour is obtained 
by (18), the size of pump is found and after this the pipes carry- 



260 ELEMENTS OF REFRIGERATION j 

ing the brine should be made of such a diameter that the 
velocity will be 4 ft. per second. The friction loss is found 
by using the equation: 

(20) 



S= summation sign; 
L = length in feet of any size pipe; 
d = diameter in feet of any size pipe; 
w = velocity in feet per second; 
n = number of elbows of any size pipe; 
L' and d' = dimensions of elbow; 

f = coefficient = -, '-- - ; 

(dw)* 

Pumping work per hour = M V XH. . . (21) 

Cold-storage warehouses are sometimes operated from a 
central refrigerating plant. These central stations will pay 
when there are a number of persons needing refrigeration within 
a limited radius. In the warehouse districts of Boston, New 
York, Philadelphia, Baltimore, Norfolk, St. Louis, Kansas 
City, Denver and Los Angeles and in the hotel district of 
Atlantic City central stations have been installed. The lengths 
of mains vary from i to 17 miles and the income amounts to 
about $12,000 per mile. The systems may be of the brine 
system or the direct-expansion system. In each case there 
must be at least two mains, a supply and a return. In the brine 
system the pipes must be carefully insulated, as the brine is 
at low temperature and about i\ H.P. is required by the brine 
pump motor per ton of refrigeration to drive the brine through 
the main. The pipes are put in wooden boxes after covering 
them with hair felt soaked in rosin and paraffin oil. The 
box is waterproofed. The arrangement of the box is shown 
in Fig. 133. In this one set of pipes is arranged in a wooden box 
while in the other a split-tile conduit is used. The pipe is 
carried on supports at i2-ft. intervals for 2-in. pipe and over, 
while for i-in. pipe 8-ft. intervals are allowed. At certain 
points the pipe line is anchored and on each side of this anchor 



COLD STORAGE 



261 



expansion is allowed to take place. Expansion amounts to 
0.08 in. per 100 ft. for each 10 of temperature change. Expan- 
sion joints are placed at about 175 ft. intervals and should be 
of the pipe bend or swinging ell type, although the slip joint 
as shown in Fig. 134 is used. The anchor points should be 




FIG. 133. Conduits (or Refrigerating Pipes. 

points at which branches are taken off. The pipes used for 
brine may be of cast or wrought iron. 

In the direct-expansion system there is no need of insula- 
ting the supply main, as this will not absorb heat from any- 
thing as cool as or cooler than the cooling water, since the 
ammonia is under pressure. The return main should be in- 



262 



ELEMENTS OF REFRIGERATION 



sulated, although this is not necessary if the ammonia vapor 
is warmed by the abstraction of heat in the storehouse to at 
least earth temperature. In direct-expansion installations it 
is customary to run three mains with cross-connections at man- 
holes and warehouses. One pipe is used as the pressure main, 
one as the return and a third as a vacuum line to be used when 
it is desired to test the piping in buildings. This line can be 
used to charge the pipe system of a building with compressed air 
for testing or for any other purpose. The joints in this system 
should be welded, as leaks are very expensive, ammonia being 
worth about 25 cents per pound. The cost of ammonia to 
charge such a system is another of the drawbacks. The 




FIG. 134. Expansion Joint for Ammonia Line. 

pressure in the suction main would be fixed by the coldest 
temperature necessary in any warehouse, and usually a drop 
of 15 Ibs. is allowed in the main to drive the vapor. The 
main should be anchored at points with expansion allowed 
for by bends in manholes. 

The load for such a station is figured by allowing i ton 
for about 3000 cu.ft. for spaces up to 40,000 cu.ft. For insu- 
lated areas an allowance of noo sq.ft. to the ton will care for 
walls, floor and ceiling. The temperature on the three hottest 
consecutive days is used in computing the peak load. These 
may be found by getting the records of the nearest weather 
bureau office. 

For brine lines bell and spigot cast-iron pipe has been used. 
Voorhees has installed 1500 ft. of lo-in. pipe of this kind and is 



COLD STORAGE 



263 



supplying two warehouses of a total capacity of 1,500,000 
cu.ft. He could not detect a rise of temperature in this length 
on thermometers reading 2 to ", showing that the gain of heat 
in the duct was not great. 

The pipes should be installed perfectly dry and kept that 
way. Paint is of little value when pipes become wet. The 
best thing to use as a paint is some form of bituminastic 
solution. 

AUTOMATIC REFRIGERATION 

The use of automatic apparatus by which the tempera- 
ture of rooms is kept constant is one of the recent develop- 



Temperature- 
Suction Control 




FIG. 135. Automatic Refrigerating Plant. 

ments of the art. In this method an electric device controls 
the expansion valve and the pressure in the expansion coil 
regulates the motor operating the compressor. In a similar 
way the pressure in the discharge main controls the water supply 
to the condenser and on the pressure reaching a limiting high 
value the apparatus is shut down, thus guarding against the 
failure of the condensing water supply. 

The claim for such a machine is that the amount of refrig- 



264 ELEMENTS OF REFRIGERATION 

eration is just that which is needed. It will be easily under- 
stood that when a room is cooled off below the required tem- 
perature the heat flow is increased and more work than that 
necessary for the plant is done. In automatic installations a 
constant temperature may be maintained and one no lower than 
that required. Of course this also prevents the temperature 
from rising above the desired point, and although this would 
rarely happen in a well-operated plant, a much lower tempera- 
ture may be carried to prevent it. 

To obviate the necessity of charging refrigerator cars with 
ice, compressor plants have been proposed. For instance 
in Ice and Refrigeration for May, 1910, there is a description 
of a patented system in which a small compressor is placed on 
the car. A device exhibited in Paris in 1900 for the Russian 
railroads is worth noting. In this a tank of liquid ammonia 
was placed beneath the car and connected to an expansion coil 
in the car. An absorber filled with weak liquid was attached 
to the other end of the coil, absorbing the vapor and main- 
taining a low pressure in the system. Enough liquid ammonia 
is carried for a given run and at the end of this run the liquid 
cylinder and the absorber are removed and replaced by new 
ones. The liquor can then be boiled and the ammonia regained 
and liquefied. In this way the most remote points of the car 
may be kept cool. 

The cold storage of foodstuffs on refrigerator cars has been 
recently improved by precooling the car and its contents before 
shipment. This is accomplished by forcing cold .air in at o.ie 
end of the car and drawing out warm air from the other. 
After a given length of time the current is reversed and air is 
drawn from the end into which it was forced, and withdrawn 
from the other end. In this way a large amount of heat can 
be taken from the car before ice is introduced. 

There are several of these preceding stations. The Santa 
Fe System has one at San Bernardino, California, and the 
Southern Pacific, one at Roseville, California. At these stations 
twenty-four to thirty-two cars are placed in connection with 
ducts which are covered with a heat insulator. By movable, 



COLD STORAGE 



265 




266 




' 

1-lt"* 

w (3 



ELEMENTS OF REFRIGERATION 

telescopic or bellows tubes either the 
main door or one of the ice hatches is 
connected to one duct and both ice 
hatches or the other ice hatch is con- 
nected to another duct. The connection 
and ducts are well insulated. Air is then 
blown over brine coils or direct-expan- 
sion coils in a bunker room and is 
delivered at about 10 F. to one of these 
ducts, the ice forming on the coils from 
:j the moisture in the air being removed 
3 by blowing over warm air when the cold 

* brine is cut off or by the use of calcium 

JO 

3 chloride brine which trickles over the 

^ coil. The air is then delivered by fans 

5 to a duct and then by means of tele- 

i scopic tubes to the car, where it is 

3 wanned 20 or 25 F. and is drawn out 

3 through another duct by the suction 
a of other fans. The pressure of the 
1 forcing fan is from \ to f in. of water, 

- while an equal vacuum is produced" by 

4 the suction fans giving atmospheric 
S. pressure at the car door. This is neces- 
" sary on account of the leaks through the 
\ car walls. The air currents in the car 

are arranged to reach all parts and by 
a system of valves the air currents from 
the ducts are reversed in the cars. The 
fruit should be arranged in tiers sep- 
arated for ventilation. In some cases 
the air discharged into the car is shut off 
while the suction is continued, giving a 
partial vacuum in the car. On admitting 
the cold supply this enters the parts 
of low pressure. The vacuum also tends 
to draw out some of the gas from the 



COLD STORAGE 267 

fruit. At San Bernardino the rate of 6000 to 8000 cu.ft. per 
minute per car is used for a period of four hours, reducing the tem- 
perature of car and goods to 40 F. The arrangement of the car 
is shown in Fig. 136. Fig. 137 shows the general arrangement 
of the plant, which represents an investment of about $900,000. 

After these cars are reduced to 40, or the temperature 
desired, they are iced at the station and then shipped east. 
The car may then be sent to Chicago without further icing 
and the fruit will be in far better condition than when treated 
with ice in the ordinary way. The cost of refrigeration as 
ordinarily run with ice from California to Chicago is $62.50 
per car, while after precooling and original icing by the shipper 
the further icing is reduced to $7.50 per car. The cost of 
precooling is $30.00 per car and the original icing is $25.00. 

At Springfield, Mo., the United Fruit Co. cool their cars 
by this method, lowering the temperature 26 in twenty-four 
hours. In this way they may be held cold, the rise being 
2 or 3 in 500 miles of travel. 

At these precooling stations ice is made for charging cars, 
and for that reason the plants are equipped with ice storage 
rooms. A storage plant is necessary for the cooling of the cars 
and the manufacture of ice. The plant equipment is as follows: 

Santa Fe at San Bernardino, Cal. : 

Ice-making capacity: 225 tons per day. 

Ice storage: 30,000 tons of ice (day room 900 tons). 

Compressors : two 30o-ton Vilter refrigerating machines. 

Cars at one setting: 32. 

Bunker rooms: 44 ft. 6 ins. by 48 ft. by 9.3 ins., and 8 ft. 

9 ins. 
Fans: eight i2o-in. Sirocco fans, 65,000 cu.ft. per minute 

each at f in. 
Insulation: 3-in. cork on concrete. 

Pacific Fruit Express Co., Roseville, Cal. (S. Pac. Co.) ; 
Ice-making capacity: 250 tons per day. 
Ice storage: 20,000 tons (112 by 115 by 32 ft. and 75 by 
115 by 32 ft). 



268 ELEMENTS OF REFRIGERATION 

Cars atone setting: 24. 

Bunker rooms: 80 by 26 by 9 ft. and 8 ft. high. 
Compressors: two 25o-ton York compressors. 
Insulation ice house: concrete walls with 3-in. lith. 

Air duct i-in. boards: |-in. asphalt, i-in. boards, 3|-in. 

granulated cork, i-in. boards. 
Fans: four fans 85 in. diameter, 27! in. wide, 44,500 cu.ft. 

per min. at 380 R.P.M. Pressure 3 oz. 

That this is not an untried invention is shown by the fact 
that over 22,000 cars have been precooled at the Santa Fe plant 
alone during a period of about five years. 



CHAPTER VII 
ICE MAKING 

In making ice two methods have been used for a number 
of years. In one, distilled water is placed in cans and these 
cans are surrounded by brine, liquid ammonia, or cold air, 
which removes heat from the water and causes it to freeze. 
In the other, water taken from a stream or other supply (known 
therefore as raw water) is placed in a large tank which con- 
tains a number of coils of pipe for vaporizing ammonia or cir- 
culating brine. This removes heat from the water until 
gradually a plate of ice is formed on each face of the coil. 
If a large tank, 20 ft. wide by 60 ft. long by 8 ft. deep, contain 
20 coils, 40 plates of ice could form. The first method is 
known as the can system; the second as the plate system. 

To study the peculiar details of these systems two general 
plans will be examined, after which the details of construction 
and operation will be considered. 

Figs. 138 and 139 are the plan and elevation of a 2 5 -ton 
standard can system of the York Mfg. Co. In the plan view, 
Fig. 138, the compressed ammonia is delivered from the com- 
pressor to a double-pipe condenser, passing through a separator 
before entering the condenser. From this point the liquid 
ammonia is carried to an ammonia receiver shown dotted and 
seen in Fig. 140, and it is then taken to a liquid line on top 
of the brine tank at A, Fig. 139. From the liquid line it passes 
through expansion valves and enters the expansion coils of i |-in. 
pipe shown in the longitudinal section, Fig. 139. The liquid 
enters at the top of the coil and flows down to the bottom, 
abstracting heat from the brine. From Fig. 140 it will be 
seen that there is a coil between each two rows of cans. The 
manifold or pipe line A leading the liquid to the coils is carried 



270 



ELEMENTS OF REFRIGERATION 




ICE MAKING 



271 




272 



ELEMENTS OF REFRIGERATION 



in a box filled with cork, as seen in Fig. 139, to prevent the 
abstraction of heat from the room after leaving the expansion 




FIG. 140. Cross Sections of 25-ton Ice Plant. York Mfg. Co. 

valve. The cans are 3oo-lb. cans, and the tank, which is 49 ft. 
9 ins. by 21 ft. by about 5 ft., contains 352 cans, or fourteen 
3co-lb. cans per ton of capacity per twenty-four hours. The 



ICE MAKING 



273 



cans are n|" by 22%" by 44". The brine-freezing tank is 
made of |-in. steel and is well insulated on the sides. As 
shown in Fig. 141 the brine is given a circulation by means of 
a propeller blade driven by a motor or 'belt from an engine. 
This propeller is placed on one side of the end of the tank 
and by running a vertical partition longitudinally along the 




Propeller 



Freezing 



Tank 



FIG. 141. Plan of De la Vergne Freezing Tank with Brine Agitator. 

center of the tank to within 2 ft. of each end a channel is made 
to cause a definite circulation. 

The vapors formed in the coils are collected in a return or 
gas header and are taken to the suction of the compressor. 
This line, Figs. 138 and 140, is carried through a storage 
water tank so as to remove heat from the distilled water which 
is to be placed in the cans. This completes the passage of the 
ammonia and the compressor delivers the ammonia again 



274 



ELEMENTS OF REFRIGERATION 



to the condenser. The water from the storage tank is taken 
to a point on the outside wall of the center of the freezing 
tank length and then discharged by a hose into cans which 
have just been emptied. An automatic device shown in 
Fig. 142 cuts off the water supply when the tank fills. These 

fillers are of various forms, dif- 
fering in detail. The K-C Filler 
shown in Fig. 142 has a ball at 
the top of the discharge pipe, the 
raising of which closes the valve 
controlling the flow of .water. 
This is lifted by the water as it 
fills the can. 

When the water is frozen 
the wall of ice grows from the 
surfaces of the can and gradually 
forms a core at the center. All 
of the impurities in the water 
are forced toward this point, as 
the ice first forming is clear, and 
if the water is dirty or contains 
scum an opaque core is found 
at the center. Hence the water 
in the early methods was dis- 
tilled and boiled to prevent the 
formation of this core. For this 
reason the exhaust steam was 
condensed and used. In the 
plant shown, Figs. 139 and 140, 
the exhaust from the engine is 
carried through a grease separator to a condenser placed on 
the roof of the boiler house. From here the condensed steam 
is carried to a reboiler. In this the water is brought to a 
boiling temperature by a steam coil and the oil and other im- 
purities remaining in the condensed steam as well as air are 
forced out. 

This reboiler is placed in the monitor of the roof. The water 




FIG. 142. K. C. Can Filler. 



ICE MAKING 



275 




276 



ELEMENTS OF REFRIGERATION 



is then taken through a cooling coil and finally passed through 
several filters for cleaning and deodorizing before entering the 
storage tank. 

When the water in the can is frozen it is taken from the brine 
tank by a crane operated by compressed air to a can dumper 
in which the ice is freed from the can and sent to the ante- 
room, from which it is passed into the ice-storage room. This 
room is cooled by a coil of pipe in which liquid ammonia is 
allowed to evaporate. 

Attention is called to the insulation of the freezing tank 
and the ice-storage room. 

The table below gives the various dimensions of York plants 
of different sizes with necessary data: 















Lin.ft. cf 




Tons. 


Boiler 
Room. 


Compression 
Room. 


Tank 
Room. 


Storage 
Room. 


Ante 
Room. 


iJ"Exp. 
Coil in 


300-lb. 




Wdth. Lgth. 


Wdth. Lgth. 


Wdth. Lgth. 


Wdth. Lgth. 


Wdth. Lgth. 


Brine 


Cans. 














Tank. 




10 








20 X 27 


20 X 8 


2.500 


1 60 


30 


18 X 56 


25 X 56 


28 X 53 


28 X 43 


28 X 10 . 


7.500 


320 

480 


50 


18 X 56 


^25 X 56 


28 X 97 


28 X 97 




12.500 


800 


75 


18 X 56 


25 X 56 


28 Xi28 


28 Xi28 




18,750 


I2OO 


IOO 


18 X 56 


25 X 56 


28 Xi58 


28 Xi58 




25,000 


I6OO 



Fig. 143 gives the outline of a 50-ton Frick can ice plant 
from which dimension may be taken. 

In Figs. 144 and 145 the arrangement of a plate system 
for 50 tons capacity as designed by the Frick Co. is shown. 
In this plant a producer gas engine is used to drive the com- 
pressor, as raw water may be used and there is no need of dis- 
tilled water. 

The ammonia is compressed in a vertical compressor and 
delivered to a double-pipe condenser placed on the second 
floor of the engine house, Fig. 144. From the condenser it 
is taken into a receiver A in the freezing room near the wall 
and then delivered to a header B running along the freezing 
tanks. In the figure shown there are seven tanks about 20 ft. 
long, 10 ft. wide and 10 ft. deep, each well insulated against 



ICE MAKING 



277 




278 



ELEMENTS OF REFRIGERATION 




ICE MAKING 279 

heat loss. In each of these tanks are four direct-expansion 
coils supplied from a header connected to the main liquid line. 
By throttling the ammonia is allowed to enter the coil and the 
vapor is taken off from the mixture leaving through the main 
suction pipe C at the top. The arrangement of feed is such 
that there is much liquid left in the coil at the top and the 
mixture is taken from the top of the coil to an accumulator D 
where the. vapor is separated, the liquid passing back into the 
lower part of the coils. On each side of an expansion coil is 
placed a heavy sheet of steel on which the ice forms. This 
ice forms gradually, taking six or seven days to make 12 ins. 
of ice, the plate weighing about 6 or 7 tons. As the ice forms 
the impurities are forced ahead of the ice, leaving clear ice from 
raw water. To release the ice when ready to harvest, the liquid 
is cut off from the coil and warm vapor is allowed to enter 
from the header E, this melts the ice from the plate and steam 
or warm brine is passed through pipes placed beneath the 
tank and on the sides to melt the ice from the sides and bottom 
of the tank. This is the only function of the thaw pipes shown 
in Fig. 144. 

The plate of ice is now lifted by a crane, using iron rods 
frozen in the ice to carry the load and after placing the plate 
on a tilting table and bringing it to a horizontal position, a saw 
is used to cut the ice into small blocks. The saw is mounted 
on a motor and moves on a sliding table. The blocks are 
stored in the anteroom or in the main storage room. 

The tanks are carefully insulated and the piping beyond 
the expansion valve is covered to prevent loss of refrigerating 
power. The tanks are well braced. The arrangement of 
piping is such that when warm ammonia is introduced from a 
special line the condense^ ammonia may be drawn from the 
coil by a liquid transfer _ header. The liquid ammonia could 
go to one of the coils using ammonia liquid. The size of each 
tank is sufficient to give the complete tonnage of the plant 
for one day so that this tank can be emptied of ice and filled 
with fresh water the same day. The water remaining with 
the impurities is taken off. This would require that the num- 



280 ELEMENTS OF REFRIGERATION 

ber of tanks equal the number of days required to freeze the 
ice to its desired thickness. The plant shown will make about 
50 tons. 

With plate ice raw water may be used and there is no need 
of distilled water. Hence high-grade steam engines, gas engines 
or electric motors may be used for the prime movers. The use 
of the electric motor when power is taken from a central station 
during the off-peak hours of a public service company, furnishes 
a cheap method of driving, as the off-peak rate may be very 
low. The Chicago Edison will sell off peak power at i cent 
per kilowatt hour. In the figures shown the plant is driven by 
gas engines throughout. The water-circulating pump, the 
agitator blower, the air pump for the deep well, the electric 
generator and the filter pump are driven by a small gas engine. 
Air-storage tanks for starting the gas engines are placed on the 
side of the room. The gas producer and coal-storage room 
may be seen. 

The cold-water storage tank is used to cool the raw water 
after it has been filtered. This filtering is resorted to to take 
out suspended matter and bacteria. 

Having the general arrangement of the two systems, it will 
be advisable to examine the peculiar apparatus used with 
each. 

The distilled water apparatus is of various forms. When 
there is sufficient steam from the engines an arrangement is 
used as shown in Fig. 146. This is that used by the York 
Mfg. Co. The exhaust steam from the engine passes through 
an oil separator and feed-water heater and then to a condenser, 
where it is condensed by water used in the ammonia condenser. 
The line is equipped with a free exhaust valve set to relieve 
the pipe after a certain pressure is. reached. The condensed 
steam is then collected hi a return tank, from which it is pumped 
into the reboiler. This reboiler is operated with steam from 
the exhaust main or from live steam with the condensate pass- 
ing to the exhaust line. After reboiling the water is passed to 
a double-pipe water cooler and is delivered to a storage tank 
after passing two filters and a regulator. The cooling may be 



ICE MAKING 




282 



ELEMENTS OF REFRIGERATION 



done by warm condensing water from the condenser or by a 
cool supply. The amount of skimming in the reboiler regulates 




the flow of water through the system by taking the scum 
to the regulator. 



ICE MAKING 283 

When the exhaust steam is not sufficient to supply the dis- 
tilled water required, some form of evaporator is installed by 
which the exhaust steam is used to evaporate water and thus 
increase the yield of distilled water. At times the Lillie evap- 
orator is used, although any type may be employed. A single 
effect evaporator (one evaporator only) is in general sufficient 
for an ice plant. 

The arrangement of such a distilled water system as pro- 
posed by the De La Vergne Co. is given in Fig. 147. In this 
the exhaust from the engine passes through a pipe containing 
a free exhaust valve and passing through a grease separator 
enters the space around a set of tubes in a vertical evaporator. 
These tubes are held between tube plates and are filled with 
raw water which rises to a point above the upper tube plate. 
The condenser B has a vacuum maintained by the air-pump 
at such a pressure that the water in the tubes of the evaporator 
boils and passes over to the condenser. The boiling of the raw 
water removes the heat of the exhaust steam and this con- 
denses around_the tube and collects on top of the lower tube plate. 
The condensate is drawn over through pipe A to the steam 
space of the condenser by the vacuum in B and is allowed to 
flow by gravity into the vacuum reboiler which is connected 
at the top to the steam space of the condenser. The air pump 
G is connected to the condenser above the water level and 
removes only air and vapor. The reboiler is freed from water 
by the pump H, which has an automatic float control in the 
reboiler. The reboiler takes live steam from the pump supply 
and the condensate from the coil is caught in a reservoir from 
which it is drawn by the vacuum in the reboiler whenever the 
valve K is opened by the float. 

The exhaust steam discharged from the engine may be 
by-passed around the evaporator by closing D, I and E and 
opening F and by partially opening D; when F is closed and 7 
and E are open, some of the engine steam is allowed to flow 
to the condenser without evaporating any water. In this way 
the amount of distilled water is regulated. 

The reboiled water is pumped into the skimmer and then 



284 ELEMENTS OF REFRIGERATION 

enters the hot-water storage tank and passes successively 
through the cooler, deodorizer and fore-cooler. The storage 
tank for hot water is provided with a float so that when this water 




FIG. 148 De la Vergne Grease Separator. 

is low the butterfly valve on the final discharge pipe is closed 
and prevents water from being drawn away. The atmospheric 
water cooler is cooled with water which may be used later for 
water supply. The deodorizer is a charcoal filter to remove 




FIG. 149. York Reboiler. 

odor and certain suspended matter. In the fore-cooler the 
water passes from it through a set of pipes which are cooled 
by ice water flowing over the set. This ice water is pumped 
from a tray beneath the coil and passed first over pipes which 



ICE MAKING 285 

contain low- temperature ammonia gas or ammonia liquid. 
In this way the cooling water is cooled and there is no danger 
of freezing the water within the lower pipes, as the flowing 
water cannot reach a point below 32 unless it freezes on the 
outside of the ammonia coils. 




FIG. 150. De la Vergne Reboiler and Skimmer. 

The arrangements in these figures give the general outline 
of all apparatus for distilled water. 

The arrangement of the grease separator of the De La 
Vergne Co. is shown in Fig. 1480 The action of the baffle 
plates on the steam and oil is to remove the oil and water. 

The reboiler of the York Co. is shown in Fig. 149 while 
Fig. 150 gives that of the De La Vergne Co. In each of these 
a steam coil causes the water to boil and thus drives off air or 



280 ELEMENTS O*F REFRIGERATION 

other gases, while the oil which forms a scum is taken off by the 
skimming edge of the holes at the right-hand end of the outlet 

chamber. 

The niters are vessels containing a layer of quartz sand 




FIG. 151. Sand Filter. 

on top of which is placed charcoal. This removes the last 
suspended matter as well as the odor and taste, and in order 
to clean this an occasional supply of steam can be admitted 
to melt off the oil which may * collect. The same can be done 
to the pipes of the condensed water cooler. See Fig. 147. 

When raw water plants are used the filters may be of the 



ICE MAKING 



287 



sand type as shown in Fig. 151. In this there is a large shell 
of steel containing a number of collecting heads in a lower 
diaphragm, through which the water passes after traversing a 
4-f t. thickness of graduated sand, fine at the top where the water 
enters and coarser as the bottom is reached. By introducing a 
small amount of alum solution from the coagulent box into the 
water in inlet pipe the suspended matter coagulates and collects 
on top of the bed. This collection, known as the " schmutz- 
decke," gradually becom.es so thick that filtration is slow. The 
current is then reversed by valves A and B, the water entering 




FIG. 152. Frick Distilled Water Storage Tank. 

from the bottom by E, while valve D is closed and a valve to 
one side of A connects the top to the sewer. In this way the 
washing removes the deposit from the filter. A glass cup shows 
the condition of the water passing. After the main washing 
is completed, the current is reversed to its proper direction 
and the discharge allowed to waste to the sewer through a valve 
on the left of E until the water is clear, after which it is cut 
off from the^sewer and passed back to the line. The maximum 
amount of water cared for by such filters with safety is 2.5 
gallons per minute per square foot of filter bed. 

If a storage tank is used in place of the fore-cooler the 
water is cooled by the circulation of ammonia. The ammonia 



288 



ELEMENTS OF REFRIGERATION 



is either allowed to evaporate in a coil in the tank or the cool 
ammonia vapor from the expansion coils is taken through the 
coil and is warmed by the extraction of heat from the water. In 
this way ammonia may be superheated on entering the com- 
pressor. Fig. 152 is a view of the Frick storage tank with the 
coil shown as if the tank were transparent. 

The construction of the freezing tank for the can system 
of the De La Vergne Co. is shown in Fig. 141. The inner 
partition makes a circulation from an agitator positive, as 
shown by the arrows. The coils are arranged so that two 




FIG. 153. Frick Flooded System. 

are controlled from one branch. In the figure liquid ammonia 
is carried to the bottom of the coil and the vapor is taken from 
the top. This is the arrangement used with the new flooded 
system which has been introduced within the last few years. 
As shown in Fig. 153 this system consists in supplying liquid 
to the lower part of the expansion coil in large -quantities so that 
the liquid will rise through a vertical branch into the accumu- 
lator to a point above the level of the top of the expansion 
coil. Then as the suction pressure is decreased by the action 
of the compressor there will be not only a further rise in the 
liquid through the liquid line but also a flow of vapor and liquid 



ICE MAKING 



289 



through the upper pipe leading from tank to accumulator. 
The accumulator acts as a separator, allowing the liquid 
separated to flow out at the bottom, while the dry vapor flows 
to the compressor or to the coils of the filtered water-storage tank. 
The level of liquid in the accumulator is carried near the 
bottom and the check valve leading to the liquid line allows 
liquid to flow from the accumulator. 

The reason for the employment of this system is the fact 
that when all the pipes of the coils have 
liquid ammonia in them they are all 
effective and moreover there is a slightly 
better transfer of heat due to a high 
coefficient for liquid to liquid. In the 
ordinary system certain of the upper or 
lower pipes are filled with vapor because 
of the danger of getting liquid into the 
suction line and as a result these pipes 
are of little value since, after the liquid is 
vaporized, there can be little if any ab- 
straction of heat, because the brine is prac- 
tically at the same temperature as the 
vapor. Little heat can be abstracted to 
superheat the vapor. There is a small 
amount of heat transfer in these pipes, but 
small because the ammonia could not take 
up the heat rather than that the coefficient 
is small. In the flooded system (invented 
by J. Krebs in 1890) liquid ammonia finds 
its wav to the highest coils and although 
mixed with much vapor it may remove 
heat from the last foot of pipe. As a result 
of this the pipe surface necessary for a 
given tonnage may be decreased from 300 
lin.ft. of ij-in. pipe per ton to 180 feet per ton, although with 
longer pipe, not absolutely necessary, the efficiency of the plant 
is higher. 

The structure of ice cans is shown in Fig. 154. The various 



FIG. 154. Ice Can. 



290 



ELEMENTS OF REFRIGERATION 



manufacturers make these cans in about the same shape and 
size. The following sizes are used by the largest manufacturers : 

ICE CAN DIMENSIONS 



Weight of Ice. 


Width and 
Breadth at 
Top. 


Width and 
Breadth at 
Bottom. 


Length Inside 
Over All. 


Galvanized Iron, 
Thickness. 


5 


8X8 


75 X 7* 


31 32 


No. 16 U.S.S. 


IOO 


8 Xi6 


7sXi5l 


31 32 


16 


200 


11^X22^ 


IO^X2l 


31 32 


16 


300 


1x1X3*1 


IO^X2li 


44 45 


16 


400 


IliX22^ 


IO|X2I^ 


57 58 


14 



The band around the top is made of by 2 -in. iron for the 
three largest sizes and by if for the other sizes. The iron 
is turned over at the top and bottom and is well riveted and 
soldered. All metal is galvanized. 

The cans are handled by electric hoists or air hoists as shown 
in Fig. 155. These are mounted on light traveling cranes 
which carry the tanks to the ice dump. The air hose or electric 
cables are hung from roller hangers so placed that the loops 
will not reach the floor. 

The ice dump, Fig. 156, is arranged so that when a can with 
ice is placed within it, the center of gravity is above the point of 
support and it may be easily placed in an inclined position. 
This motion turns on the water sprinkler. When the water 
has melted enough ice to free the cake, it slides out and leaves 
the can and frame in such a condition that the center of gravity 
is below the support and the frame returns to the vertical 
position, automatically shutting off the water. The water 
which issued from small holes in the pipe is caught in the tray 
and sent to the sewer and the ice slides free of all contamina- 
tion. This is necessary, as the brine washed from the outside 
of the can should not come in contact with the ice. 

The latest improvement in the can system of ice making 
has been the use of raw water for can ice. There have been, 
numerous methods suggested for the production of clear ice 
from raw water. The raw water can ice of the earlier day was 
quite opaque and although as valuable for cooling as clear 



ICE MAKING 



291 




FIG. 155. Can Hoists. 




FIG. 156. Frick Can Thawing Dump. 



292 ELEMENTS OF REFRIGERATION 

ice this opaque ice would have little if any value for domestic 
service. When the water was filtered the cake would be fairly 
clear if little air was present except for the central core, and 
hence proposals were made to form a large cake and then cut 
this into four pieces on lines passing through the core, placing 
the opaque part on one edge. It was also proposed to freeze 
all but the core and then to remove this water containing the 




FlG. 157. Double Drop Tube. De la Vergne Co. 



this 



impurities and introduce enough distilled water to fill 
space. 

To prevent the formation of opaque ice it was found neces- 
sary to agitate the water while freezing to prevent the reten- 
tion of the small air bubbles which cause the whiteness. One 
method of -agitating this water (patented in Italy in 1877 by 
Turretini) is to introduce air at the bottom of the can at a pres- 
sure slightly above that due to the water depth and this air 
jet produces necessary agitation. The air is introduced at the 
center of the bottom as shown in Fig. 160 entering in one of 
several patented ways. In Fig. 157 the air is introduced by 



ICE MAKING 



293 



a drop tube. The tubes are connected to a tee which is placed 
on an air outlet of the air pipe running between every other 
pair of cans on the framework which carries the top of the 
tank. The connection to the air main is made so that the drop 
tubes may be withdrawn from an automatic self-closing valve, 



Rotmrj Bloer COM Pump 



Jt 
I 




FIG. 158. Plan of De la Veigne Raw Water Ice P.ant. 

which prevents air discharge when the connection is removed. 
As the impurities gradually collect at the center in the core 
space they are finally drawn out by the core pumps and the 
space filled with distilled water or good clear raw water which 
has been filtered as carefully as the original water used. 

The general arrangement of the core-pump hose and 
refilling hose is shown in Fig. 158. In this figure will be seen 



294 



ELEMENTS OF REFRIGERATION 




ICE MAKING 295 

the general arrangement of one air-supply header running from 
the main header which receives air from the rotary blower. 
The core pump is connected to two lines of hose which may 
be put in any can for the removal of the core water. This 
amounts to about 10 Ibs. in 3oo-lb. cans. The water from 
the fore cooler is attached to four large hose lines for filling 
tanks and to two small ones for filling the cores, the same 
water being used for each purpose. The motors driving four 
agitators are shown in the figure. 

The air taken into the blower is first cooled to remove the 
moisture from it so that this moisture will not freeze in the air 
headers or drop tubes. The air is taken from the atmosphere 
at a high point in the plant and passed to a header from which 
it enters a series of pipes, Fig. 159, over which water near 
32 F. is passed. In this way the air is cooled and the moist- 
ure in the air is condensed and dripped from the collecting 
header before the air enters the air main. The air may be 
taken through a screen to remove dust or any form of air 
cleaner may be used. The water is taken by a small centrif- 
ugal or rotary pump from the cold-water storage tank and dis- 
tributed over the air coil, after which it falls over an ammonia- 
expansion coil, which cool's it to about 32 F. This water is 
then collected in the tank from which it is pumped to the cans 
as needed or back over the air coil. The air thus dried will 
not clog the drop tubes as it enters and meets the cold walls 
of the tube. The pressure necessary for 30o-lb. cans is about 
2 Ibs. per square inch, due primarily to the amount of sub- 
mergence of the end of the drop tube. This air keeps the 
water agitated and thus wipes off any bubbles of air which 
might cling to the surface of the ice. 

In Fig. 1 60 the tube A is fastened to the side of the can 
and in this the air is forced from the end B through the ice 
as it forms, leaving a small seam through which air flows, driving 
the water out of it and keeping the water above agitated and 
driving the impurities gradually to the top D of the can. This 
leaves the hollowed top of ice with all impurities above the grid 
F in the unfrozen water. This water is thrown away when 



296 



ELEMENTS OF REFRIGERATION 1 



the can is taken out and the grid with the ice on it is removed, 
leaving clear ice of uniform length for storage. The grid also 
serves to freeze the center cup at the end due to the conduction 
of the iron. In this system the pressure has to be increased as 
the ice forms. This of course is automatic through the use of a 
valve which throttles the air discharge until resistance is brought 




FIG. 1 60. York Raw Water Can. 

on by the formation of ice. The pressure at the pump remains 
constant, being used up in pipe and valve friction when first 
applied, and finally the ice friction requires the full pressure 
as the ice closes in. The gauge pressure is about 18 Ib. per 
square inch. The power used in the compressor is about o 4 
H.P. per ton of capacity. The air used amounts to i .8 cu ft per 
can per minute at start to 0.3 cu.ft. per minute after freezing 



ICE MAKING 297 

The two methods described are those used by two large 
manufacturers. There are many other methods employed which 
have given satisfaction. For instance, the agitation has been 
accomplished by drawing water from the core and then allow- 
ing it to discharge back again, this back and forth motion pre- 
venting the formation of opaque ice. One of the first methods 
was to rock the cans and after this, agitation was by rods and 
then by air discharge. Another method patented' by Ott Jewell 
is an ice can in which the brine is passed through a double 
wall of the can and air is introduced at bottom to agitate. The 
Beal patent of 1913 is similar to the York method described 
above. The Ulrich patent brings the air pipe in on the out- 
side of the can. 

The plate system accomplishes the result of the raw-water 
can system without the complication of air-pump or rocking 
apparatus. On account of the increased space and an increase 
of about 30 to 70% in the initial cost, due to the larger building, 
the plate system is not installed as frequently as the can system. 
In 1915 the De La Vergne Company stated that there were 
150 plate plants in operation in the United States. Of course 
with the plate system almost any kind of water may be 
used. 

The generation of the liquid ammonia may be accomplished 
by an absorption system as well as the compression methods 
described. The arrangement of the ice apparatus is practically 
the same when the absorption system is used to compress the 
ammonia. If an absorption system is placed where compres- 
sors are shown in the previous figures the apparatus would 
be that used by the makers of that type of apparatus for ice 
making. 

There are more than one thousand plants in the United 
States, of which about 81% are operated by compression and 
1 8% by absorption. The output of these is over twenty- 
three million tons of ice. The natural ice crop is probably 
equal to or greater than this. The curve of delivery of ice 
will follow the curve of temperature difference above 32 F., 
although there may be some changes due to manufacturing 



298 



ELEMENTS OF REFRIGERATION 



or other application of ice. In any case it is well to draw a 
consumption curve to be expected or known from previous 
records. From this curve the capacity of the plant and the 
size of the storage room may be 
found. 

These various methods are ap- 
plicable in special cases. The plate 
system is advisable with expensive 
fuel and very poor water, while with 
better water the raw-water can sys- 
tem may be used. When fuel is 
cheap the distilled can system may 
be used and when there is exhaust 
steam from other machines the ab- 
sorption system should be employed. 
The absorption system may be 
operated in an isolated plant with 
economies as good as the compres- 
sion system. 

The water for ice plants is 
usually taken from deep wells. The 
wells are rarely artesian and the 
water has to be pumped. The pumps 
are of various forms. Deep-well 
pumps have a pump bucket operated 
at the end of a long rod by a steam 
piston in engine room, Fig. 161. An 
air-lift pump is one, Fig. 162, in 
which compressed air is allowed to 
enter the water pipe and by aerat- 
ing the column of air and making 
it lighter than the water outside of 
FIG. 1 6 1. Deep- well Pump, the casing it drives the water out of 
the discharge main. Other pumps 

are used. The air-lift pump has the advantage of being simple 
to install, and of having all of the working parts accessible as 
well as being able to deliver a large quantity from a given well. 




ICE MAKING 



299 




FIG. 162. Air-lift Pump. 




FIG. 163. Oil Separators. 



300 ELEMENTS OF REFRIGERATION 

It is very inefficient in the use of power and hence is more expen- 
sive to operate. Its advantages are such, however, that the 
pump is extensively used. 

The power to drive a deep-well pump may be figured from 
the quantity M w and the lift H as 

M nH 

H.P. for deep-well 



M v = weight of water per second in pounds per second; 
H = height in feet from water level in well to discharge 

nozzle; 

Eff. = 70% for deep-well pump from steam to water; 
= 3% f r air-lift pump from compressor motor to 
water. 

. WXH 
Air per minute in cubic feet of free air = -. 

W = cubic feet of water per minute. 

To treat water from which the oil cannot be removed in 
the ordinary way A. A. Gary suggests in the Transactions of the 
American Society of Refrigerating Engineers to pass the water 
through a long coke filter, or to pass the steam through a 
steam washer in which the steam has to pass through water 
or over water as shown in Fig. 163. An enlarged chamber on 
the steam main to cut down the velocity of the steam and per- 
mit the steam to come in contact with a series of screens was 
also suggested. 

In planning for the amount of distilled water for an ice 
plant an allowance of a waste of 25% of that turned into ice 
must be made. 

If the amount of steam from the various machines is not 
sufficient to supply the necessary distilled water some form of 
evaporator as shown in Fig. 147 must be used. Fig. 164 
shows the form of Lillie evaporator. In this exhaust steam 
from the engine and other auxiliaries is discharged at H and 
enters the tubes E, which have a reduced oressure within, due to 
the suction through the small holes drilled in the caps of the 
left-hand end of each of them from the low pressure which 



ICE MAKING 



301 



exists in B. This low pressure is caused by a vacuum pump 
attached to a condenser which is joined to the evaporator 




by the pipe N. Water from the sump K is pumped by 
the centrifugal pump L through M to the G box whence it 
discharges through eleven pipes F and falls over the pipes E. 



302 ELEMENTS OF REFRIGERATION 

This water is heated and condenses some of the steam inside 
of the tube E, and the pressure is so reduced that the water will 
boil at a lower temperature than that of the steam inside. The 
evaporation of this water will cause further condensation 
of the steam inside. The condensed steam drops to the front 
of C and is removed. As the water in the shell is evaporated 
the sump box K does not contain enough water to lift the float 
and hence more water is introduced. When the water in A 
becomes heavy with salts after evaporating a lot of water, 
the heavy liquid is removed by opening R. ^ 

To compute the necessary surface and size of evaporator 
the following equations may be used: 

From the equation 

Ms (i' i -i' () )=M w (i" i -i" )+Q e , . . . (i) 

the amount of water M w from the steam M, is found. In 
this 

M s = weight of steam condensed per hour; 
M w = weight of water evaporated per hour; 
Q e = heat radiated from covered evaporator, computed 

from Chapter V; 
i'i and i' = heat contents of dry steam entering and water 

leaving at pressure of exhaust steam ; 

* "o and i"i = heat contents of dry steam leaving at pressure 
assumed in B (20 less than entering steam) and 
of the entering water. 

The surface is figured by 






to = temperature of entering steam; 
t' = temperature of steam leaving; 
^ = 400. 

An important consideration in planning an ice plant is the 
sanitary condition around the plant. Since ice is to be used 
for domestic purposes and may be introduced into food or 



ICE MAKING 303 

drink, it is necessary that cleanliness be insisted upon. The 
men walk over the covers of the cans, and dirt on the footwear 
may fall into the cans, hence there should be no chance for 
the workmen employed in harvesting from going through 
places when contamination may occur. The floor of water- 
closets for instance should be kept so clean that nothing can cling 
to the footwear. The water-closets should not be placed so 
that workmen would have to pass through stable yards or 
over roadways to reach them. In many ice plants conditions 
exist such that men must pass through regions where the boots 
take up this contaminating matter. The' condition of the water- 
closet should be bright and clean. Money spent here on tile 
work and terazzo flooring is not wasted. 

The wells or springs from which the water is taken must be 
placed so that they may not be contaminated by materials 
blown by the winds or from ground or subsurface seepage. 
The use of cesspools for water-closets should not be tolerated, 
especially where wells or springs are used for water supply. 

To keep the plants clean they must be so constructed that 
dirt will show, and hence the covers, walls and all parts of the 
plant should be painted white. It is also advisable to have no 
one walk over the tank tops who does not put on rubber over- 
shoes which are not worn anywhere else. 

Freezing Tanks. Freezing tanks are usually made of steel 
plate with insulation beneath and around them. This is shown 
in Fig. 141. The insulation is sufficiently heavy to cut down 
the heat loss to a low value. The thickness is fixed by finding 
the minimum yearly cost due to heat loss, interest, depreciation, 
taxes, insurance and maintenance. The tanks for the plate 
system are sometimes made of timber. These must be care- 
fully braced whether of wood or metal because of the depth. 
Reinforced concrete has been used for brine tanks. The bottom 
and sides are made of 6 or 8 ins. of concrete with f in. reinforc- 
ing bars placed i ft. apart and 2 ins. within the concrete from 
the brine side. This is followed by 2 ins. of cork board and 
then five layers of tar felt put on with hot coal tar, on top of 
which is placed 2 ins. of concrete with a smooth finish. To cut 



304 



ELEMENTS OF REFRIGERATION 



down the heat transfer a thick layer of cinder may be -used 
around the tank, 16 ins. of dry cinder being equal to 2 ins. 
of cork. There is a difference of opinion as to the advisability 
of using concrete for the brine tank, as some claim calcium 
chloride disintegrates the concrete, but others say that concrete 
is perfectly satisfactory. 

In planning the size of brine tanks the time of freezing must 
be assumed and sufficient cans or plate tanks must be installed 
to give the required capacity. In plate work one freezing tank 
should be large enough to give the required output. If the 
weight of ice is taken 57^ Ibs. per cubic foot, the volume of the 
plates for the given tonnage, assuming a thickness of 12 or 
14 ins., may be found, and from this the volume of the tank, the 




-'".-: 




FIG. 165. Reinforced Concrete Brine Tank. 

depths being about 10 ft. and the widths 16 ft. The time of 
freezing the plate ice is given by Macintire as 



(3) 



h = hours of freezing; 

a = thickness; 

//= temperature in refrigerating pipes. 

This takes about six days, so that six or seven tanks are 
used. The number of cans is found in the same way. If the 
smaller thickness of the can is represented by a, then the time 
is given by Macintire as 



3*-*/ 
a = thickness of can at top. 



(4) 



ICE MAKING 



305 



In this way the total output during the freezing is 

h X tons. 

And the number of cans is given as 
AX tons 



Wt. per can 



= number of cans. 



. - (5) 



Ordinarily fourteen 3oo-lb. cans are used per ton of capacity. 
This means fifty hours for the formation of the ice. If the 
number of cans is increased it means that there is a longer time 
for the ice formation and hence a smaller difference in brine 
and water temperatures, which means a higher back pressure 
and less work, while a decrease in the number means a lower 
brine temperature to give the smaller time for freezing. This 
means a lower back pressure on the compressor and hence more 
work. It is well to compute the yearly cost of ground, build- 
ing and equipment against the cost of power in figuring the 
number of cans. To compute the temperature of the brine a 
value of 2.6 for K is used. This same thing is true in regard 
to the number of tanks in the plate system. To show this 
Thomas Shipley has computed the following table: 

EFFECT VARIATIONS IN CAN ALLOWANCE HAVE ON HORSE-POWER REQUIRED 
TO PRODUCE ONE TON OF ICE. (With Single-acting Compr.) 



I 


2 


3 


4 


5 


6 


No. 3oo-lb. 
Cans Per 
Ton Ice 
Making. 


Average Brine 
Temperatures 
Needed to 
Produce Ice. 


Rate of Heat 
Transmission 
B.T.U. per 
Sq.ft. per Hr. 
i MD. 


Temperature 
Required in 
Pipe. 


Corresponding 
Evaporating 
G. Pressure. 


Total Brake 
H.P. per Ton 
Ice Making 
1 85 Lbs. C. P. 




op 


for Pipes. 


F. 


Lbs. 




10 


7 


15 


3-3 


13-3 


77 


12 


1 1 


IS 


+0.7 


16.2 


.56 


14 


14 


15 


3-7 


l8. 5 


45 


16 


16 


15 


5-7 


20 


352 


18 


18 


IS 


7-7 


2I.y 


.27 



Note. Evaporating surface in the freezing tank assumed in this table is 
108 sq.ft. or 250 ft. of ij-in. pipe per ton of ice. 

Note. Tables are based upon the water to be frozen being delivered to the 
cooling and freezing system at 70 F. 

Work done by cooling system = 30 B.t.u. per pound of ice. 

Work done by freezing system = 200 B.t.u. per pound of ice. 



306 ELEMENTS OF REFRIGERATION 

Expansion Coils. In the coils of brine tanks the liquid 
ammonia may enter the upper or lower pipe. When the flooded 
system is used the liquid is introduced at the bottom, and it 
seems unreasonable to bring it in at any other point if the coil 
is to receive its full supply of liquid. In this case the vapor 
header may be drained to the low liquid line to return any 
liquid unevaporated. This really gives a flooded system. 
Before the wide introduction of the flooded system there was a 
great difference of opinion over this point among the refriger- 
ating engineers, but this matter seems to be settled by the 
adoption of the flooded system. 

In some cases the brine may be cooled in a brine cooler 
on one of the types shown in Figs. 19, 8 1 and 82 and the brine 
pumped to the freezing tank. Such a device is not so good 
as the use of expansion coils in the freezing tank, as this 
method keeps the brine at a low temperature throughout by 
abstracting heat from it as it abstracts heat from the freezing 
water. 

The amount of this surface in a brine tank is figured by 
allowing a value of K of 15 due to the low velocity of the brine 
over the coils. In a brine cooler especially of the double pipe 
type or the shell type a much higher value of K is used, due to 
the higher velocity of the brine. Since this method is rarely 
used the case of the expansion coil in the tank will be con- 
sidered. It has been found that 120 to 150 lin.ft. of ij-in. 
pipe is sufficient to care for a ton capacity with ordinary coils 
and about 80 ft. have been found necessary in the flooded 
system. In any case it is a matter of abstracting the heat and 
if the surface is cut down the back pressure must be decreased 
to give the necessary temperature difference. This means 
greater power for the same refrigeration. One must compute 
the yearly cost on investment on pipe against the cost of power. 
Assuming sixteen cans per ton, Thomas Shipley has computed 
a table showing the effect of change of pipe length. 

The powers required are the powers applied to the compres- 
sors to drive them, whether by belt, direct-connected motor or 
engine. The auxiliaries require about 0.3 to 0.4 H.P. 



ICE MAKING 



307 



EFFECT OF VARIATIONS IN EVAPORATING SURFACE ON HORSE-POWER REQUIRED 
TO PRODUCE ONE TON OF ICE WITH SINGLE-ACTING COMPRESSOR. 



I 


2 


3 


4 


5 


6 


7 


Lineal Ft. 
of ij-in. 

Ton of Ice 
Making. 


Sq.ft. Pipe 
Surface, 
External. 


Rate of 
Heat Trans- 
fer for 
Pipe = X. 


Average 
Tempera- 
ture of 
Brine. 


Tempera- 
ture in 
Pipe. 


Gauge Press 
in Coil. 


Total Brake 
H.P. per 
Ton of Ice 
Making at 
185 Lbs. 
Comp. Pres. 








F. 


F. 


Lbs. 




15 


65 


15 


16 


I.I 


14.85 


.661 


20O 


8? 


15 


16 


3-2 


18.1 


.468 


250 


108 


15 


16 


5-7 


20.0 


352 


300 


130 


15 


16 


7-45 


21-5 


.279 


350 


152 


15 


16 


8.7 


22. 5 


.218 



The pressure of compression has an important bearing on the 
efficiency of the plant. An endeavor should be made to use as 
cool water as possible for the condenser to keep this pressure 
low.* The effect of this is seen in the following table by Thomas 
Shipley: 

POWER REQUIRED PER TON OF ICE AT DIFFERENT CONDENSING PRESSURES 
WITH A SINGLE-ACTING COMPRESSOR WORKING UNDER A SUCTION PRESS- 
URE OF 20 LBS. 



















Condensing pressure 


85 


105 


125 


145 


165 


185 


205 


225 


245 


Corresponding Tem. 


47.6 


58.6 


68.1 


76.6 


84.2 


91 . o 


97-3 


103.2 


108.9 


H.P. per ton of ice . . 


1.162 


1.408 


1.646 


1-874 


2.114 


2.352 


2.587 


2.851 


3.098 



The rule for the number of tanks and size of the expansion 
coil has been worked out on the assumption of 200 B.t.u. 
per pound of ice in the freezing tank and 30 B.t.u. per pound 
in the cooling tank. Of course there are average results, but 
in some cases the quantity must be computed owing to peculiar 
conditions. The heat to be removed in the cooling system 
per pound of ice made, if 15% excess is allowed and water is 
at t F. and is to be cooled to 32 is 

& = i.i5^ ....... (6) 



* If water has to be pumped and is bought, a calculation must be made for 
the cost of water and of power for the compressor and for the pump for different 
quantities of water and the one giving the best result used. 



ELEMENTS OF REFRIGERATION 



The heat of fusion is 143.4 B.t.u. and the specific heat of 
ice is given by 

(7) 



c = specific heat ice; 

t = temperature of ice in degrees C. 

This has been tabulated by Dickinson and Osborne as 
follows : 

HEAT TO FREEZE ONE LB. OF WATER AT 32 AND TO COOL ICE TO TEMPERATURE. 



t 


Q 


t 


Q 


/ 


Q 


20 


167.2 


-2 


159-5 


16 


151.2 


-18 


166.3 





158.6 


18 


150-3 


-16 


165.5 


2 


157-7 


20 


149-3 


-14 


164.7 


4 


156.8 


22 


148.4 


12 


163.8 


6 


155-9 


24 


147-4 


10 


163.0 


8 


155-0 


' 26 


146.4 


- 8 


162.1 


10 


154-1 


28 


145-4 ' 


- 6 


161.3 


12 


153-1 


3 


144-4 


- 4 


160.4 


14 


152.2 


32 


*43-4 



The heat used then will be 



= i84 B.t.u. approx. 



(8) 



Although only 184 B.t.u. are needed, the radiation will be 
an additional amount, making 200 B.t.u., used by Shipley. 
The radiation loss may be computed. 

The size of pipes for brine, ammonia and water are com- 
puted by method of Chapter VI. 

From the curve of ice consumption, as shown in Fig. 166, 
the main demand for ice can be found and the question arises: 
Is it better to put in enough ice-making capacity to carry the 
peak load, having idle machinery during a large part of the year, 
than to install apparatus for the mean capacity and operate 
at this capacity, storing at time of low demand to carry the 
amount demanded at times above the mean curve? This 
problem is one which can be computed. The extra apparatus 



ICE MAKING 



309 



and plant needed beyond that for mean load is found and the 
cost of interest, depreciation, taxes and insurance is compared 
with the cost of storing, loading and removing ice, including 
the cost of the building. 

To store ice and hold it from spring to midsummer and then 
take it from storage costs 25 to 30 cents per ton according to 
W. E. Parsons. J. N. Briggs increases this by the yearly cost 
of the storehouse, 15 cents brings the cost to 40 or 45 cents 
per ton. This includes the expense of holding, and in this 



ns per 24 Hours 
















































































23F. 


23 F. 


33 F. 


46F. 


59F. 


68 


73 


71 


63 


51 


39 


28 
























Mean 


Pleight 




H 
100 



















































































Jan, Feb. Mar, Apr, Hay June July Aug. Sept. Oct. Nov. Dec. 
Months 

FIG 166. Curves of Tons per Day. Arranged for months for Troy, N. Y. 
Monthly average temperature for forty years. 

problem the cost of insulation is compared with that of absorb- 
ing the heat transferred to determine the amount of insula- 
tion. After this is fixed the amount of heat loss is found and 
cared for by melting ice or by refrigerating coils. The latter 
method is the better, as it is cheaper to cool the room than to 
make an equivalent amount of ice to do this. The data from 
a storehouse of this kind will be mentioned. 

From the amount of heat to be supplied by the brine coils 
in the freezing the surface may be computed by assuming the 
temperatures of the water in cans, brine, and ammonia. Call 
these t w , /&, and t a , 



310 " ELEMENTS OF REFRIGERATION 

Can surface in sq.ft. per ton of ice 

= 20ooX[i.i5(?/+(M = 6410 , , 

24X2.6[t w -t] 32 -fc' 

Coil surface in sq.ft. per ton 



The amount of refrigeration for plant per ton of ice 



199.2X24 



An ice-storage plant in Philadelphia for 10,000 tons of ice 
is 113 ft. long, 78 ft. wide, 60 ft. high. It is built of brick 
22 ins. thick. It has a 6-in. reinforced concrete roof carried on 
girders. The insulation of the walls is two 2 -in. cork boards 
held in place with cement and furnished with a cement plaster. 
The floors are of concrete over which two 2-in. cork boards 
are laid in hot asphalt for insulation. The ceiling is insulated 
with 3 ins. cork attached by Portland cement to the rein- 
forced concrete. To refrigerate the room, 15,000 ft. of 2-in. 
wrought-iron pipe for direct expansion are used. This held 
the room at 22 F. in the warmest weather. To handle the 
ice, plunger elevators with oil and brine as the working fluid 
are used. 

Ice is stored in these houses in such a way that the ice will 
not press against the walls and the blocks should be so placed 
that they will make a stable pile. This is important. 

In distributing ice it is well to use a map of the city and 
plan routes so that they will not overlap. Inspectors must be 
employed to watch men and foremen to direct their work. 
To guard against loss of money ice books are sold by drivers, 
who are held responsible for them, and in addition the amount 
of ice delivered to the driver and the amount sold by him must 
receive a daily check. It is best to use a single-horse wagon 



ICE MAKING 311 

in charge of one man, since where two men are on the wagon 
there is apt to be talking, drinking and more waste of time. 
To encourage better work it is well to give a bonus. 

The use of 3-ton automobile trucks has been found to cut 
down the expenses of distribution in the saving of time in reach- 
ing the point of delivery. This is especially true if the truck is 
used to carry ice to the delivery wagons. In using automobile 
trucks the work must be arranged to handle ice quickly. There 
must be no waiting, as the fixed charges are so great that unless 
a large volume of work is done, there is loss. 

Solicitation of trade in an unobtrusive way, care in adjust- 
ing all complaints and judicious use of advertising will bring 
good results. It is absolutely necessary for the foreman to be 
acquainted with the kind of service given to consumers. 



CHAPTER VIII 
OTHER APPLICATIONS OF REFRIGERATION 

THE use of refrigerating in various industries is increasing. 
In a recent list of applications over one hundred industries 
were mentioned in which refrigeration played an important 
role. A few of these will be described. 

In the manufacture of candy, especially chocolate-coated 
candy, there is a necessity for a uniform temperature to set 
the chocolate and to give uniform results. Cool air is blown 
into the rooms to keep them at a temperature of about 68 F. 
as chocolate cannot be dipped above 72. This air may 
either enter from an overhead duct at 50 F. and be used to 
cool the room enough to 'set the chocolate, or air may be intro- 
duced into setting boxes shown in^Fig. 167. The chocolates 
are placed in this box as soon as one plate has been filled with 
dipped chocolates. By pressing a pedal the plates in the box 
are raised to admit a new plate from beneath. The plates are 
separated by distance pieces so that there is no danger of the 
candies being mashed by contact. Cool air is introduced 
into the interior of the box from the duct A and before entering 
the room this air chills the candy, setting the outer coating. 
The heat which it removes would have to be removed in any 
case to hold the room at 65 or 68, and so this apparatus requires 
no extra refrigeration, but it applies the cool air where it will 
do the greatest good. The springs B B hold the plates in 
position. This is employed by Harter & Co. of Ohio. They 
have a 6^ -ton machine, cooling a bunker 5'Xs'X22', using 
five stands of 2-in. direct-expansion pipes 12 ft. high and 20 ft. 
long for cooling. A 52-in. Buffalo Forge Fan at 120 R.P.M. 
drives the air through a 24-in. riser to i6-in. pipes with 3~in. 
branches leading to the cold boxes. This saves refrigeration, 
312 



OTHER APPLICATIONS OF REFRIGERATION 



313 



as the room need not be cooled to such a low temperature. 
In the plant under discussion the 72 boxes, each caring for 
150 Ibs. of chocolate per day, required 6| tons while it would 
require 15 tons for the ordinary cool room according to the 
designer. 

At the Baker Chocolate Plant six loo-ton absorption 
machines are used to supply 40,0x30 lin.ft. of 2-in. galvanized 




FIG. 167. Setting Box for Chocolates. 

iron pipe. The pipe is carried throughout the plant and 
bunkers and fans are placed where required. 

The specific heat of chocolate is given as 0.9 by Siebel, 
and he also recommends the air to be supplied at such a satura- 
tion that the relative humidity at room temperature is 72%. 

The heat removed in this case is similar to that for the 
blast furnace as given on p. 324. The heat from the walls 
of the buildings, machinery, lights, persons and chocolate 
are given by the following: 



314 ELEMENTS OF REFRIGERATION 

Heat leaking through walls per hour 



Heat from machines and lights per hour 

(2) 



Heat from persons = Qp = NaQ f .......... v3) 

Heat from chocolate = Q C = M C X 0.9 X(k -/r) ...... (4) 

K = coefficient of transmission B.t.u. per deg. per sq.ft. 
per hr.; 

F = square feet of different wall areas; 

t a = outside temperature; 

t r = temperature of room; 
HP = horse-power of machines; 

N = number of lights; 
Q fl = heat per hour per light; 
N 2 = number of persons; 
()' = heat per person; 
M c = weight of chocolate per hour; 

t c = temperature of chocolate; 

Q = Q e +Qi+Q P +Qc. 

In breweries the refrigerating machine is of great value. 
Here the cooling of liquids and the removal of the heat of fer- 
mentation are the chief applications. 

After the beer is brewed the solution, known now as wort, 
has to be cooled and this is done usually in a Baudelot cooler. 
The Baudelot cooler, Fig. 168, consists of a series of horizontal 
pipes formed in a coil through which cold water is passed and 
below this is another coil in which liquid ammonia is allowed 
to boil or brine or cold water is circulated. Over these coils 
the hot wort is distributed. The wort is exposed to the air 
and will take up oxygen, thus throwing down certain matter 
in solution, and also there is some solid matter thrown out 
due to the cooling. The room in which this occurs is usually 



OTHER APPLICATIONS OF REFRIGERATION 



315 



enclosed in glass or copper so that it may be kept clean and 
free from foreign bacteria, which would produce growths not 
desired in the fermentation. This cooling is intended to 
reduce the temperature to prevent bacterial growth should any 
enter. The heat removed from the wort depends on the range 
of temperature and the specific heat. The specific heat varies 
from 0.941 at specific gravity 1.032 to 0.861 at specific gravity 
1.0832, with a negative allowance of 0.00015 f r ea ch degree 




FIG. 168. Frick Baudelot Cooler for Beer Wort. 

above 60 F. The ordinary drop in temperature is from boil- 
ing to 110 F. in a storage vat and then the wort is passed 
over the cooler and reduced to 70 F. on the upper coil and to 
from 40 to 50 F. on the lower coil. 

The beer is then taken to fermenting tubs where the sugar, 
formed in the operation from the starchy matter by the diastase 
which was produced by the change of barley to malt, is split 
up into CO 2 and alcohol by the action of yeast added to the 
wort for the fermentation process. The bacteria of the yeast 



316 



ELEMENTS OF REFRIGERATION 



take up oxygen and also nitrogen. This action produces 
heat and as a rise in temperature would make brewing difficult 




I 

FIG. 169. Brewery Plant Showing Cellars and Beer Cooler. AfUr De la Vcr L ne. 

and because the beer is to be reduced gradually in temperature, 
it is necessary to cool this liquid in the fermentation tubs. 
This is done by circulating cool water through attemperating 



OTHER APPLICATIONS OF REFRIGERATION 317 

pipes. The water is cooled in the attemperator by brine or 
direct expansion. 

After this the beer is placed in storage tubs to age and 
finally put into large casks, where it is properly finished off. 
From this point it is placed in kegs for shipment. This is 
known as racking. 

The heat removed is the heat leakage through the walls, 
Qu', the heat from the Baudelot cooler, Q b ; the heat from the 
attemperator, Q h for the fermentation. 

The heat Q w is computed in the manner mentioned before 
as soon as the temperatures of the rooms are fixed. The fer- 
menting room is kept at 42 F., the storage rooms at 33 F., 
the cask rooms at 36 F. and the racking room at 32 F. 

The heat Q h is given by 

<2 6 = vol.X62. 5 Xsp.gr.Xc(/ 6 -/ / ), .... (5) 

V = volume of wort per hour in cubic feet; 
sp.gr. = specific gravity = i .05 mean ; 
c = specific heat = 0.9 mean; 
/ = temperature from brewing = 150 to 190 F.; 
//= temperature to tubs = 40 F. 

According to Siebel the heat removed in fermentation 
is given by 



Afm = lbs. of maltose split up per hour into CO 2 and alcohol; 
330 = B.t.u. produced by the breaking up of i Ib. of maltose. 

This may be written as 



M a = lbs. of alcohol produced per hour. 

This usually amounts to a ton of refrigeration per 40 to 
J3> barrels per day. The total refrigeration of the brewery 
amounts, according to Siebel, to a ton for every four barrels 
per day. 



318 ELEMENTS OF REFRIGERATION 

The amount of surface may be computed by the methods 
of Chapter V. Ordinarily the Baudelot wort coolers are made 
of ten 2-in. pipes 16 ft. long for fifteen barrels of beer per hour 
to cool the wort from 70 to 40 by the use of direct ammonia 
expansion. With brine these pipes would care for ten to twelve 
barrels per hour. The water portion of the cooler to cool the 
wort from 170 to 150 to 70 would be made of about the same 
number of pipes. These pipes may be made of copper. In 
the at tempera tors, coils are made usually of a coil diameter 
of two-thirds the tub diameter. Twenty-four square feet is 
allowed by Siebel per 100 barrels of wort. The rooms for 
storage of hops should be held at about 36. 

The cooling of air is one of the modern applications of refrig- 
eration. This, cooling is not always undertaken to obtain 
cool air, for it is used in blast-furnace work where warm air is 
needed, but in this case the cooling is to reduce the moisture 
content of the air. Air at any temperature may contain a 
definite quantity of moisture, and when this amount is present 
it is said to be saturated. The amount of moisture per cubic 
foot to saturate the air is different for each temperature. It 
amounts to the weight of i cu.ft. of steam at that temperature. 
The air and moisture are really the mixture of several gases 
and a vapor, and by Dalton's law the amount of each constit- 
uent is proportional to its partial pressure. The moisture 
or steam may exert the pressure corresponding to its tempera- 
ture if saturated, and with this pressure the weight must be that 
required to produce saturation. If the air is not saturated the 
moisture is in a superheated condition. The ratio of the amount 
present to the amount required to saturate the air is known 
as the relative humidity, as was stated on p. 50. The 
method of finding the relative humidity was given on p. 175. 
From Fig. 92 it is seen that air of relative humidity 0.90 and 
of temperature 85 contains 13.7 grains of moisture per cubic 
foot. If this air is cooled to 82 F., it will be saturated, and if 
cooled to 70, it can only contain 8 grains of moisture. So that 
5.7 grains must be thrown out of suspension. If the air is 
cooled to 36 F., the air contains only 2 grains per cubic foot. 



OTHER APPLICATIONS OF REFRIGERATIO. 319 

Thus in the summer, warm air may be passed over a set of 
coils containing cool brine and when this air is delivered into 
building it will be cooled and contain less moisture than in its 
first atmospheric state. 

If atmospheric air is always cooled to a low temperature, 
say 34, before being introduced into a system, the air will 
always contain the same amount of moisture no matter what 
the original relative humidity of the warm air has been. It 
is this fact which has been applied by James Gayley to the 
drying of blast-furnace air. 

In an article by Gayley in the Transactions of the American 
Institute of Mining Engineers, he points out that in the Pitts- 
burg district the variation of monthly average temperature is 
from 31.7 to 76.2 during the year, the amount of moisture 
per cubic foot in these two cases being 1.83 grains and 5.60 
grains. The moisture varies from 0.56 to 8.78 grains, changing 
by large amounts even in one day. In January this change 
was from 0.56 grain to 0.88 grain on the same day and from 
5.55 to 5.74 grains on a day in July. This means that although 
the ore, and coke and limestone have a definite composition 
within 10% variation, the moisture content may vary 100%. 
This results in a varying amount of coke to care for the dis- 
sociation of the moisture and a difference in iron produced. 
The ordinary furnace uses about 40,000 cu.ft. of air per minute 
and this contains 40 gallons of moisture per hour for every grain. 
To make this uniform Gayley proposed to cool the air and after 
trying an experimental installation he applied it to the Isabella 
furnace at Etna, Pa. 

In this plant the air is drawn over the pipes A , which are 
supplied with brine. These pipes are arranged in three coils of 
twenty-five 2 -in. pipes, 20 ft. long. The three coils are placed 
above each other and are supplied from the headers C and dis- 
charged into the 4-in. headers B. The colls are arranged with 
staggered 2 -in. pipes and there are sixty coils in the width of 
the bunker room, making iSo^coils of twenty-five pipes. Cross- 
walls divide the coils into four sets. There are 90,000 lineal 
feet of pipe. The room is 44 by 28 by 36 ft. and is lined with 2- 



320 



ELEMENTS OF REFRIGERATION 






FIG. 170. Gayley Air Cooler. 



OTHER APPLICATIONS OF REFRIGERATION 321 

in. cork. Air is drawn in by fan D and put into the space E 
under 1.2 oz. pressure to care for the frosting of the pipes and 
the closing of the air passage. The fans F keep the air evenly 
distributed over the brine coil. The air finally enters the 6-ft. 
pipe G and passes to the blowing engine and after compression 
it is sent to the hot-blast stoves. The moisture taken out 
amounts to from 3000 to 5000 gallons in twenty-four hours. 
Some of this freezes on the pipe as the brine enters at 16 F. 
and leaves at 33. The defrosting is necessary every fourth 
day, and for that reason the brine is shut off of one of the four 
compartments and the warm water from the ammonia condenser 
is passed through the pipes for two or three hours. The plant 
is equipped with two 225-ton compressors requiring 460 H.P. 
There are thirty-seven coils in the atmospheric ammonia con- 
denser and twenty submerged double-pipe brine coolers placed 
in a brine t#nk 7 ft. 6 in. deep and 22 ft. 6 in. long. The coolers 
are made of twelve double pipes, 2 ins. and 3 ins. diameter and 
are 17 ft. i2 in. long. The brine in the tank and in the inner 
tube is cooled by the ammonia in the annular space. There are 
40,000 gallons of CaCb brine of sp.gr. 1.2 in the system. The 
brine pump and fan D take 75 H.P. The total power needed 
is 535 H.P., while the three air compressors use 3 times 671 
or 2013 H.P. in place of 3 times 900 or 2700 II. P., as was 
required with the warm air. The smaller power is due to the 
smaller volume occupied by the cooler air with small vapor 
pressure. There is a slight saving in power, but the main 
saving is in the amount of coke used and in the uniformity of 
operation; 358 tons of iron were made with 2147 Ibs. of coke 
per ton originally while 447 tons per day were made with 1726 
Ibs. of coke per ton after the installation of the dry blast. 
This plant was started in August, 1904, and since then a num- 
ber of plants have been installed. In general the output may 
be increased by 10% and the saving in coke is 15% when this 
apparatus is used. 

Gayley has patented a scheme of passing the air through 
two coolers in series and using cool liquid to abstract the heat. 
In this case air is blown in at A and passes up through grids or 



322 ELEMENTS OF REFRIGERATION 

baffles over which a cold liquid such as water falls. The water 
is pumped by the centrifugal pump C to the top of the tower 
where it is discharged over brine or direct-expansion coils D, 
which cools off the water and this flows down over the grids. 




FIG. 171. Gayley's Two-stage Air Cooler. 




FIG. 172. Air Conditioning Apparatus. 

The cooling of air for churches, hotels and auditoriums or 
for rooms used in some manufacturing process is accomplished 
in the same way. In this case the air is freed from the pre- 
cipitated moisture by first passing it through water to wash it 
and then over a set of baffle plates arranged as in A, Fig. 172, 
called eliminators for the purpose of removing the moisture. 



OTHER APPLICATIONS OF REFRIGERATION 



323 



The figure shows the arrangement of fan B and bunker C. 
The bunker C contains a number of pipes through which brine 
is passed to cool the air and precipitate the moisture. The 
eliminator E removes the moisture. The air enters at F and is 
passed through tempering coils G and H in cold weather. The 
washers J consist of a spray through which the air passes. This 
spray washes the air, taking out the dirt and gases. The upper 
coils C serve to warm part of the air if necessary. The mixing 




73. Bunker Room. 



dampers at K are used to get a proper temperature of dis- 
charge. 

The air may be cooled by passing it through a spray current 
of cold water or brine or the air may be passed over a set of 
revolving discs which dip into a cold-water or brine tank, and 
when they emerge they are cool and prepared to cool more air. 

Fig. 173 illustrates another bunker room with vertical coils 
made up of horizontal pipes and return bends. These are con- 
nected to two mains. The coils are filled with brine. 



324 ELEMENTS OF REFRIGERATION 

At the Congress Hotel in Chicago a 3oo-ton machine is used 
in cooling the air and washing it for proper service. 

At the Luther Memorial Church at Orange, Texas, a cooling 
plant is used to reduce the temperature from 90 and over to 70. 

The City Theatre of Rio Janeiro has recently been finished. 
This building seats 1700 persons with 200 on the stage. Over 
50,000 cu.ft. of cold air per minute is introduced to bunker, 
'cooling the air from 95 to 68. This requires 7,000,000 B.t.u. 
to cool the air and 2,340,000 to condense the moisture. The 
operation is carried out by 105 H.P. motor operating an SO 2 
compressor. 

The problem in these cases is to find the amount of refrigera- 
tion. In the case of the air for a blast furnace the known data 
consist of the amount of air to be handled per minute, Vi, 
the maximum temperature T\, the relative humidity of this 
pi and the condition to which it must be changed T 2 . 

Weight of air entering = (Bar ~ lpl)Fl =M a . (8) 

BL i 

Weight of moisture entering = m\ pi Vi= M i .... (9) 

Volume of air leaving = M BT 2 = ^ ,. 

(Bar p 2 ) 

Weight of moisture leaving = W2 ^2 = Af2 (u) 

Water condensed = M\ M 2 = M c (12) 

Energy in air above 32 entering = 0.24 M a [Ti -491] =Qi (13) 
Energy in moisture above 32 entering = M\ii] =Q 2 . (14) 
Energy in air above 32 leaving = o.24 M a [T 2 4gi]=Qs (15) 
Energy in moisture above 3 2 leaving = M 2 [i 2 ] =Q . ( 1 6) 
Energy in condensed moisture = M c q 2 ' = Qs .... (17) 
Heat removed per Tmnute = Q = Qi+Q 2 -(Q 3 +Q 4 +Qs) (18) 

mi= weight of i cu.ft.. of saturated steam; 
Bar = Barometric pressure; 
pi= pressure of steam at temperature T\\ 



OTHER APPLICATIONS OF REFRIGERATION 325 

Ti = absolute temperature of entering air; 

pi = relative humidity; 

i\ = heat content of moisture at entrance (superheated) ; 

#' = heat of liquid. 

For the cooling of buildings it is well to fix the temperature 
of the incoming air so that when heated to the temperature of 
the room it will have absorbed the heat entering into the room 
from the outside and from processes in the room. If the various 
heat losses through the walls be found from the K 's of Chapter V, 

Heat from walls Qe=2KF(t a -t r } . . . (19) 

Heat from persons Q P = nQ f ...... (20) 

Heat from machines and lights Qi = 2$46x~H..P.+Q g ni . (21) 
Now 



T -t e ) .... (22) 

o.o2=B.t.u. to heat i cu.ft. air i F; 
V = volume of air per hour; 
t a = temperature outside air; 
t r = temperature room ; 
t e = temperature of entering air. 

V is fixed by the number of persons in the room. In some 
cases this is made 1800 cu.ft. per hour per person. This may 
be reduced to 1200 cu.ft. per sitting in an auditorium where 
the number is not fixed. The value of V is given by 

V=i2oon .......... (23) 

n = number of persons. 

Having V, t e may be found and the problem is the same from 
this point as the original problem for the blast furnace. 

Having ( the heat removed from air the amount of surface 
required is given by 

~^ ....... (24) 

A/i 

rr 

A/2 



326 ELEMENTS OF REFRIGERATION 

F = bunker surface in sq.ft; 
K = 2.2\ /f iv a for wet surfaces; 
K=i + i.$Vwa for dry surfaces; 
Ah = difference in temperature between air and brine at 

entrance or exit ; 

AJ 2 = difference in temperature between air and brine at 
exit and entrance. 

The capacity of the refrigerating plant 

Tons of refrigeration = ^ .... (25) 
199.2 

The brine cooler, condenser and compressor are fixed in the 
same manner as for any other problem. 

This method may be used for the air needed and refrigera- 
tion for a chocolate factory. 

Rinks. The use of expansion coils or brine coils for skating 
rinks has been employed in many places. The pipes are placed 
close together, using about o.S sq.ft. of brine pipe or 0.6 sq.ft. 
of direct-expansion pipe per square foot of rink. The heat 
to be removed is. that from persons, walls, lights and fresh 
air. 

Ice Cream. The making of ice cream has become a refrig- 
eration problem of late years. The use of cold brine for the 
freezer in place of ice and salt was invented about 1902. 

The cream when first received is stored in rooms or vats 
at a temperature of about 33 F. It is allowed to season for 
about twelve hours and after this it is put into a mixer in which 
the various ingredients are worked together. The mixture 
is now taken to the freezer, which may be of the batch or the 
continuous form. In the- Fort Atkinson Horizontal Freezer 
of the Creamery Package Co., Fig. 174, a seamless German- 
silver cylinder with a scraper revolving against it has a brine 
coil of seamless copper pipe around it. The dasher of tinned 
bronze is caused to revolve in the opposite direction from the 
scraper. The whole tank is properly insulated. Above the 
cylinder is the feed tank to gauge the batch accurately. The 



OTHER APPLICATIONS OF REFRIGERATION 327 

arrangement at the end of the feed tank permits one to put 
fruit in at this point without placing it in the main feed tank. 
In this freezer the mixture is discharged into the main cyl- 
inder and the dasher started. The cream is churned and 
cooled, and as the. heat is removed there is a swell of about 
69% of the volume, which occurs as the cream passes from 34 




FIG. 174. Fort Atkinson Freezer of Creamery Package Co. 

to 28^ F. It depends on viscosity and the rate of freezing. 
The swell is due to air being introduced. After 23! is reached 
the cream becomes brittle and the dasher will beat down the 
cream. The cream is not frozen hard in the freezer, but when 
the swell has occurred it is drawn off while it is still thin enough 
to flow slowly and is put into cans and fixed by storage. If 
the mixture is at 34 when introduced into the freezer it will 
be necessary to operate the dasher for from twelve to sixteen 



328 ELEMENTS OF REFRIGERATION 

minutes. The cream is now put in a hardening room at o F., 
where a fan keeps the air in circulation and thus removes the 
heat to harden the cream in six or eight hours. The old method 
of submerging the can in brine is not as good as the circulation 
method. 

The freezers are made of various sizes, the 5 -gallon size 
uses f to i H.P. to drive, while a lo-gallon one takes i| to 
2 H.P., a i5-gallon, 3, and a 25-gallon, 5 H.P. 

In a drug-store plant a 3-ton Larsen machine with 5-H.P. 
motor and a /p-quart freezer with 2-H.P. motor was placed 
in a space of 2 by 8 ft. and a dry hardening cabinet 3! by 18 
by 3 ft. with a cream and fruit storage 10 by 12 by 8 ft. were 
installed. This shows what a small space is absolutely nec- 
essary. 

In computing the heat to be extracted in making cream the 
following average figures may be used, although there is some 
variation from the various flavors of cream. 

Specific heat of milk o . 90 

Specific heat of cream 0.68 

Specific heat of liquid ice cream o . 78 

Specific heat of hard ice cream . 0.42 

Heat of fusion ice cream 80.0 B.t.u. 

Temperature of hard cream. ... 10 F. 

Temperature of soft cream .... 16 F. 

The first operation is the cooling from temperature of 
receipt, or if pasteurizing the cooling from the pasteurizing 
temperature to the storage temperature, after which the heat 
loss from the storage vat is cared for. The next cooling is 
from the mixing temperature to the temperature of 34 F., 
and then the heat to reduce the temperature to 28, after which 
it is drawn out and stored. Part of the heat of fusion is taken 
out in the freezer and part in the hardening room. It may 
be assumed that one-half of the heat of fusion is removed in 
the freezer. 

An important application of refrigeration is the Poetsch 
process for sinking shafts, first used in 1885. This is used 



OTHER APPLICATIONS OF REFRIGERATION 329 

where a shaft has to be sunk through quicksand or where a 
soft wet stratum has to be penetrated. In these cases the 
side walls of the shaft would be forced out by the weight above, 
and to prevent this sheet piling or a caisson may be used, or 
when these are not possible the ground around the shaft is 
frozen. To do this a series of pipes is placed in holes left 
by a drill. This casing is put down and must penetrate the 
soft stratum. It is usually put down after a drill has bored 
a hole. By capping the end of the pipe and forcing water 
out of a small opening in the end of another pipe on one side 
of the large casing, this may be driven through the soft, sandy 
stratum by washing the sand before it. After the casing is 
put down, a separate pipe is put inside and then cold brine 
is pumped down and allowed to pass up through the annular 
space between the two pipes, removing heat from the damp 
earth, and freezing it into a solid wall, as shown by dotted 
lines in Fig. 175. In the Gobert system liquid ammonia is 
allowed to vaporize in a large casing, removing heat from the 
ground around. 

To compute the amount of heat to be removed the tem- 
perature of earth must be found and its weight determined. 
The specific heat is 0.2. The amount of water to be frozen 
must be determined by drying out a sample of the earth of 
known volume and then the heat abstracted is found by 
using the general values of specific heats of water and ice and 
the heat of fusion of ice. The brine will freeze the earth 
for about i yd. from the pipe with the ring of pipes and half 
that distance on the outside with o brine, but the cooling 
will extend about 2 yds. beyond. This cooled layer repre- 
sents the heat insulator and the heat carried across this area 
represents the heat which must be supplied to keep the ring 
frozen. The heat transmitted from zero brine amounts to 
about 85 B.t.u. per sq.ft. per hr., according to Lorenz. 

The time taken to do this may be months, and for that 
reason a non-conducting house should be built around the 
top of the cooling pipes and the brine pipes must be carefully 
covered. 



330 



ELEMENTS OF REFRIGERATION 




OTHER APPLICATIONS OF REFRIGERATION 331 

The sections of the heavy outer piping are joined on the 
inside, while the inner pipe is connected by ordinary couplings. 

Another use for refrigerating machinery is the cooling 
of drinking water. This has been demanded in hotels by 
guests, and in factories it has been required by the manu- 
facturer on account of the effect on the workman, by the 
workman for his bodily comfort, and by the legislature in laws 
for the bettering of working conditions. Of course this may 
be done by ice placed against cooling coils and ice put into the 
old-fashioned water cooler made of a barrel with a faucet, 
or the older pail and dipper, but the most hygienic method is 
to send filtered water through a brine or direct-expansion 
water cooler, then through a circuit of insulated pipe to the 
cooler again, taking off sanitary fountains at intervals. 

Dr. Thomas Darlington states that about 3! pints of water 
should be drunk daily to care for water given off from the 
body. This water is necessary to aid digestion, to carry away 
waste and to properly regulate the actions of the body. The 
amount of water required varies with the amount of muscular 
exercise and with temperature. He states that the temperature 
should be about 50, as ice water is apt to produce cramp 
and water that is not cool is so unpalatable that persons will 
not drink sufficient of it. At the National Tube Works water 
is cooled to 45 F. in summer and to 50 F. in winter. The water 
should not be carried in lead pipes, to avoid the danger of lead 
poisoning, and the endeavor should be made to filter the water 
to remove bacteria, and sediment. Filtration makes the water 
attractive. The use of the drinking-cup common to all men 
should be discontinued, because of the easy transmission of 
disease thereby. 

A large drinking-water cooling system has been installed 
by the National Tube Co. in Pittsburgh at their Continental 
Works. 

The plant supplies fountains for about 1000 men, one fountain 
being used for each thirty men. These fountains must be located 
at convenient points, so that the men will drink, and so that 
the drinking will not consume too much time. The distri- 



332 



ELEMENTS OF REFRIGERATION 



bution is made through 15,000 ft. of i|-in. galvanized steel 
pipe covered with i| ins. of Nonpareil cork. The temperature 
rises about 7 in passing the circuit. The line loops down at 
each drinking-fountain, Fig. 176, as shown by the Nonpareil 
Cork Co. in their bulletin. In this way a continuous circuit 
of cold water is obtained so that there is always a discharge 
of cool water when the faucet is opened. 

The water from the city nitration plant is first passed 
through two charcoal and gravel filters and then to a tank 




FIG. 176. Drinking Fountain. 

containing direct expansion coils, reducing the water to 45 in 
summer and 52 in winter. It is passed by means of a pump 
through three lines leading to all parts of the mill. The in- 
stallation uses a lo-ton refrigerating machine for this plant. 
The amount of water, including waste, varies from about i gal. 
per man per day of ten hours in winter to 2 \ gallons in summer. 
The cost of this plant was $1.82 per employee per year against 
about $5 per man when ice and water tanks were used 
with the loss of men's time from sickness due to cold water. 
The system cost about $9000 to install. 

In planning a system, \ gallon per hour per person should 



OTHER APPLICATIONS OF REFRIGERATION 



333 



be allowed to cover all wastes for summer use with hard mus- 
cular labor. In less active work this might be decreased to 
^ or TO gallon. In carrying this water a study must be made 
of the cost of pumping, which decreases with the size of pipe; 
the cost of heat loss through the insulation, which increases 
with the size of pipe; and the yearly cost of the covering and 
pipe for interest depreciation, taxes, and insurance, which 




i Compressor ^Cork Insulation 

FIG. 177. Diagram of Drinking Water Plant. 

varies with the size of pipe. The first demands a large pipe, 
the second and third a small pipe. The yearly cost of several 
pipes should be figured, and that requiring the smallest cost 
used. The Nonpareil Co. recommend a velocity of about 
3 ft. per second, which is considered in Chapter X. This 
figure may be used as a starting-point. A low velocity pre- 
vents the disturbance of any sediment in the pipe. The piping, 
of course, is arranged in a loop from the cooling tank back to 



334 ELEMENTS OF REFRIGERATION 

.the tank. The fixtures are connected to the main flow pipe, 
as no dead ends are used. Long sweep elbows and bends 
will reduce the cost. The pipe may be covered by^ special 
ice-water pipe covering of Nonpareil cork if ins. thick and 
specially made for this service. 

The heat required for such a system is made up of two parts : 
(a) the heat to cool the drinking water to 45 F. in summer 
and (6) the amount to care for the radiation from the pipe 




4 6 8 10 . ia UK; 

Pipe size in inches 

FIG. 178. Heat Loss per Lineal Foot of Pipe per Hour per Degree. 



covering. This latter should be such that the water is only 
warmed 7 in circulating through the pipe. This temperature 
is fixed by the length of circuit and the size of the pipe. The 
cork covering has been tested as shown in Chapter VI, and 
methods of that chapter may be used to compute the loss or 
0.36 B.t.u. may be taken as the loss for i in. of thickness per 
square foot of cork surface at mean circumference per hour 
per degree difference in temperature. The loss from plain 
pipe is 0.8 B.t.u. per square foot per hour per degree dif- 



OTHER APPLICATIONS OF REFRIGERATION 335 

ference. The heat loss is given in curve below for ice water 
thickness of cork, Fig. 178. 



Water needed per hour 

, .. 0.25 X No. of men at one time 



(26) 



Heat loss from pipe in any circuit = H XL, . . (27) 

# = heat loss per foot of pipe from curve for assumed 

diam. pipe; 
L = length of pipe. 

Heat loss in water flowing for 5 rise = M c X 5 . . (28) 

Hence the weight of water circulated to care for heat loss 
is given by 

Mc = Y. . .' ..... (2 9 ) 

The area to allow for a 3 ft. per second velocity is given by 

pf w +M c = /%X3X36ooX62.4 = 673,92cx?v . . (30) 
F p = interior cross-sectional area of pipe in square feet. 

The area thus found must check with that assumed for (27) 
and (29) and if it does not the assumed size must be changed. 

Heat loss in pipes = Q P = ZHL or ZM C _X 5. . . (31) 
Heat to cool water entering = Q,o = M w (gt go). 

q t = heat of liquid at temperature of city supply (80) ; 
go = heat of liquid at outlet temperature (45) F. 

Heat loss from tanks = Q t = FK(tr-to). - - - (3 2 ) 

F = area of surface of tank ; 
K = coefficient of transmission; 
7V = temperature of room; 
To = temperature of water in tank. 



336 ELEMENTS OF REFRIGERATION 

Heat equal to work, Q f = - 
h = friction drop in system. 

Tons of refrigeration = - 



77' 



60X199.2 



. (33) 



- (34) 




FIG. 179. Methods of Covering Pipes and Fittings with Nonpareil Cork. 

Fig. 179 illustrates the section of cork covering of various 
fittings and pipe, and Fig. 180 the insulation of an ice-water 
tank. This covering is made of boards of compressed cork 



OTHER APPLICATIONS OF REFRIGERATION 



337- 



and to fit around pipes the cork is molded to form and where 
separated sections come together, a waterproof cement is 
used to make a tight joint. The sections are held together 
with four copper-covered steel wires. The pipe sectional 
coverings are put in so that the half sections break joints 
as shown. The outer surface is painted with an asphaltic 
paint and cavities are filled with brine putty or granulated 
cork and paraffin. Fig. 181 illustrates the arrangement of 
the ice-water plant of a large office building or hotel. The 



,2-2 "Cork Boards 



^S 









"i 


O_ 





L 


-^ 




35 
















n 






^ 


\ 


r~~ 


r^~ 










-Fl 










































- 






- 




- 






-. 


-4' 























- 





























































.Granulated Cork 
or Brine Putty 

Flanges 



menta of 
Cork Board 



FIG. 1 80. Armstrong Covering for Water Tank. 

centrifugal pump, A, forces the water through the closed sys- 
tem. The filter B is used to supply fresh water to the cooler 
C, which is cooled by the direct-expansion coil or by brine 
around the water coil, which gives up its heat in the brine 
cooler. A close system must be used in high buildings to 
balance the great static head, so that the pump will be re- 
quired for friction only. 

In chemical works the use of refrigeration to remove heat 
is similar to that for water cooling or chocolate making. There 
is nothing special in the methods of calculation. The quan- 
tities required are : 



338 



ELEMENTS OF REFRIGERATION 



(a) Heat loss through walls, 

(b) Heat from persons. 

(c) Heat from motors. 

(d) Heat of vaporization to condense vapors in process. 

(e) Heat to cool liquids in process. 

(/) Heat of fusion to solidify liquids in process. 




FIG. 181. Drinking Water System in Hotel or Office Building. 

The sum of these quantitites gives the heat to be removed 
and consequently the tonnage. The surface to abstract this 
heat is then found by fixing the temperatures on the two sides 
of a cooling surface and obtaining the coefficient of heat transfer. 
The problem is similar to any of the others. 



OTHER APPLICATIONS OF REFRIGERATION 



339 



The application of refrigeration to the manufacturing of 
photographic supplies and to oil refining has demanded large 
installation. Another use is to prevent chemical action by 
lowering the temperature of ammunition holds of war vessels. 

The application of refrigeration to the dairy is shown in a 
cut from the Remington Machine Co. in Fig. 182. In this 
the apparatus used in a dairy is shown with the refrigerating 
machine near the office. The direct-expansion pipe used in the 
cold-storage room and in the cooler is not shown. The cold- 




FIG. 182. Complete Dairy Plant, 3o'X48'. Remington Machine Co. 

storage room is necessary to care for the milk and cream 
properly. 

The apparatus of the Creamery Package Co. shown in 
Fig. 183 gives the requirements of the modern creamery. The 
ammonia compressor draws the ammonia from the brine 
cooler placed in the storage room or above it, the liquid being 
delivered to the cooler from the condenser by an expansion 
valve. The oil trap on the line from the compressor to the 
condenser is marked as well as the liquid receiver below the 
condenser. The brine pump circulates the brine from the brine 
tank to the pasteurizer and wizard back to the cold-storage 



340 



ELEMENTS OF REFRIGERATION 



room. The milk is placed in the receiving vat and after reaching 
the proper temperature it is passed to the separator and from 
this the cream is passed to the pasteurizer and then to the wizard 
ripener, where it is allowed to age before being sent to the churn. 
It may be necessary to cool the cream in the pasteurizer or 
wizard, and for that reason these are connected by pipes to 
the brine system. For storage of butter, cream or milk a cold- 
storage room is used. 

Another application is to the manufacture of liquid air. 
It is known that the throttling action of perfect gases occurs 




FIG. 183. A Modern Creamery. Creamery Package Co. 

at constant temperature because the heat content, which remains 
constant under such action, is a function of the temperature. 
However, there is no truly perfect gas and consequently when 
gases are throttled there is a slight drop in temperature known 
as the Thompson- Joule effect. Tripler, Hampson and Linde 
used this effect to obtain low temperatures. The last one has 
given the best results and is shown in Fig. 184. In this system 
a two-stage air compressor is used. One stage compresses 
atmospheric air to 240 Ibs. per square inch pressure and the other 
stage to 3000 Ibs. per square inch. The atmospheric air is com- 
pressed in the first stage and sent through a coil around the 
cylinder A placed in the jacket where it is cooled before going 



OTHER APPLICATIONS OF REFRIGERATION 



341 



to the second stage. The air there passes through an after cooler 
around the second stage B, "after which it enters a separator C 
for oil and moisture. It then passes through a coil D, where it 
is cooled and then enters the inner pipe of a coil of three pipes 
E. In this coil the air is cooled by a current of low-pressure 
air which has been cooled to a low temperature, so that when 
the air reaches the end F of the coil it is quite cold. It is here 
allowed to expand from 3000 to 240 Ibs. by the valve G and as 
a result its temperature should be lowered 203 C. 




FIG. 184. Linde Liquid Air Machine. 

The incoming air could be cooled to 136.5 when the throttling 
is from 3000 Ibs. to 240 Ibs. per square inch absolute. 

= 203*. (35) 



Of course the air could not drop so much and the heat 
required to keep the heat content constant means that part 
of the air must be liquefied. Part of this air at 240 Ibs. is 
throttled to 14.7 Ibs. by H and is then sent out to the atmos- 
phere through the outer annular space to /. The amount left 
between G and H is four-fifths of the total air, and this is sent 

* Equation for Thompson- Joule effect. 



342 ELEMENTS OF REFRIGERATION 

back through the first annular ring. This air is at 240 Ibs. 
per square inch and is taken to the intermediate receiver of 
the compressor. This air is cooled in the coil surrounding the 
cylinder B and the coil around D removes some of the heat 
from the high-pressure gas. 

When the machine is started the air leaving at G and H 
may not liquefy, although there is a drop of 50 C. and this cools 
the next lot of gas, which of course drops to a lower temperature 
and soon liquid air appears. 

In this apparatus the liquid air which forms is collected in 
the vessel L. The air is at a low temperature, corresponding 
to the boiling temperature at atmospheric pressure. These low 
temperatures may be used for any abstraction of heat to tem- 
perature at a little above that of the air, the liquid boiling 
away as the heat is abstracted. 



CHAPTER IX 
COSTS OF INSTALLATION AND OPERATION TESTS 

THE cost of equipment, supplies, fuel and labor will vary 
from time to time and the figures given in this chapter have 
been collected, through the kindness of many manufacturers, 
as a guide to the student in determining cost of apparatus 
and manufacture. They should be used as guides only on ac- 
count of the fluctuation in prices. They were compiled in 1956, 
but prices in use before the outbreak of the European war 
were employed. 

Land. The cost of land will vary with the location in a 
city and with the city. In the outskirts of small towns it may 
be worth from i cent per square foot or $400 an acre to 5 
cents a square foot or $2000 an acre. In a small city this will 
vary from $1000 an acre to $12,000 an acre, near the railroad. 
This latter price is about 30 cents per square foot. In the 
business districts of large cities $25 per square foot has been 
paid. 

Buildings. The cost of buildings will vary with the type 
of structure. There are a number of variable units which 
enter into the problem and unit costs of various parts of a struc- 
ture are given. For preliminary estimating the total cubic 
contents of the building, including cellar, may be found and 
then a unit cost selected from the table below is used to find 
the total cost. This is known as " cubing the building." 

COST OF BUILDING PER CUBIC FOOT, UNINSULATED 

Office Buildings 

Frame 10 cts. per cu.ft., $1.00 per sq.ft. floor 

Brick and timber 13 i . 25 " 

Brick and steel 20 i . 75 

Reinforced concrete 20 i . 75 

343 



344 



ELEMENTS OF REFRIGERATION 



Storehouses 

p rame 6 cts. per cu.ft., $0.60 per sq.ft. floor 

Brick and timber 8 0.80 

Brick and steel 12 1.20 

Reinforced concrete 12 1.20 

Power Houses 

jr rame 9 cts. per cu.ft., $0.90 per sq.ft. floor 

Brick and timber " J- 10 

Brick and steel I 5 I -5 

Reinforced concrete *5 I -5 

UNIT PRICES OF BUILDING ELEMENTS 

Excavation and Hauling 

Earth ' $ -3 to . 50 per cu.yd. 

Rock 1.50103.00 

Masonry 

Ordinary brick 33 cts. per cu.ft., $8.91 per cu.yd. 

Rubble stone 22 6.00 " 

1:3:5 concrete 22 6.00 

Reinforced concrete 37 10 . oo " 

Concrete forms $3 . oo to $5 . oo per cu.yd. 

Brick chimneys $13 .00 per cu.yd. 

Fireproofing 20 cts. per sq.ft. 

Steel Work 5 cts. per Ib. 



Lumber 

Heavy Georgia pine timber 

Georgia pine joist 

Spruce joist 

Yellow pine boards 

Spruce boards 

Ship lap, pine or spruce 

Clapboards, pine or spruce 

Cypress boards 

Yellow pine flooring, vertical grain, " 

Oak flooring, " 

Maple flooring 

Shingles 

Lath (10 cts. per sq.yd. wall) 

Studding, 3"X4" and 2"X4" spruce 



$50.00 per M bd. measure 
40.00 
34-oo 
25.00 
32.00 

26.00 " 

32.00 " 

60.00 

50 . oo per M 
70 . oo " 
50.00 " 
2 . 50 to 5 . oo per M 
4-65 
30 . oo per M 



Carpentering 
Allow from one-half to full value of lumber for labor. 



Plastering 
Lime and hair 



.30 cts. per sq.yd. 



COSTS OF INSTALLATION AND OPERATION TESTS 345 



Floors and Roadways 

Asphalt facing, 2" $i . 20 per sq.yd. 

Concrete sidewalks $i . 80 

Concrete roadway, 6" o . 70 

Macadam roadway, 6" i .00 

Brick roadway i . 75 

Asphalt roadway 3 . 50 

Concrete fireproof floors 18 .00 per cu.yd. 

o.6opercu.ft. 

Partitions 

Tiles 4" thick (i2"Xi2") 5^ cts. per sq.ft. 

8" thick (i2"Xi2") 10 " 

Labor equals cost of tile. 

Roofing 

Copper roofing $25 . oo per square (100 sq.ft.) 

Slate roofing $10.00 " 

Tin roofing 7 . 50 " 

Slag roofing 4 . oo " 

Book tiles, 2" 07^ per sq.ft. 

3" o8| " 

Rain conductors, tin .12 per ft. 

Copper 35 " 



Mill Work 



Windows with sash and trim. . . 

Outer doors and frames 

Inner doors and trim 

Base boards 

Stairs. . . 



$8.00 to $12.00 
25.00 to loo.oo 

8.00 to 15.00 
.08 to . 16 per lin.ft. 

2 . oo to 10 . oo per step 



Water-closets. . 
Wash basins . . . 

Urinals 

Soil pipe (iron). 



Plumbing 



$25.00 per unit 

$12.00 per basin 

25.00 per stall 

. 25 per ft. 



White lead and oil. 

Mineral paint 

Asphaltum 

Whitewash . . 



Painting 



38 cts. per sq.yd. for 3 coats 



Building paper. . . . 

Asbestos, loose 

85% magnesia 
Hairfelt i" thick.. 



Insulation 



.... $2 . oo to $8 . oo per roll of 500 sq.ft. 

$1.25 to $2.25 per loo Ibs., filling 3 cu.ft. 

$2.00 to $3.00 per 60 Ibs., filling 3 cu.ft. 
06 per sq. ft. 



346 



ELEMENTS OF REFRIGERATION 



Cork boards: Walls. 2" thick on brick or wood walls with cement finish, erected. 

25 cts. per sq.ft. 

2-2" thicknesses, 40 cts. per sq.ft 
1-3" " 3 

2-3" ' ' 60 

Add 8 cts. for cork partition with two sides plastered. 
Floors. 2" cork board in asphalt, 3" concrete top on asphalt cov- 
ering with i" surface, 34 cts. per sq.ft. Same with 3" 
cork, 40 cts. per sq.ft. 2-2" layers, 50 cts. 2-3" layers 
60 cts. 

Ceilings. 2"of cork on concrete or wood and \" cement plaster, 27 cts. 
per sq.ft.; 3" cork, 32 cts.; 2-2", 43 cts; and 2-3", 64 cts. 
Granulated cork : Unscreened granulated cork . . $70 . oo per ton. 
-/o rescreened granulated cork ... 60.00 ' 

^ granulated cork 35 oo " 

Coarse regranulated cork 45. oo " 

Fine regranulated cork 35o " 



PIPE COVERING CORK (NET) 





COST PER POOT. 


COST PER 


BITTING. 


Size 
Pipe. 


Standard 
Brine 


Ice 
Water 


Cold 
Water 


Standard Screwed 
Fittings. 


Standard Flanged 
Fittings. 




ness. 


ness. 


ness. 


Ells. 


Tees. 


Valves. 


Ells. 


Tees. 


Valves. 


Flanges. 


1 


lo.34 


$0.27 


$0.24 


$0.46 


$o. 50 


$o . 54 


$ .20 


5 .60 


13-05 


$0.76 


i 


43 


34 


30 


54 


63 


.71 


-.20 


.60 


3.05 


.76 


i 


54 . 


43 


39 


. 71 


79 


87 


; .05 


, -So 


3-90 


.96 




63 


50 


45 


79 


.88 


.96 


50 


' .85 


4-30 


I . IO 




. i 


57 


Si 


.88 


.96 


1.04 


90 




4.90 


I . 24 


2 




.64 


57 


-96 




1.23 


35 


.90 


5.50 


I . 36 


4 


i: i 


97 


-87 


i. 60 


I. 9 


2.08 


30 


8.15 


9.20 


2.05 


6 


I . O 


1.34 




2.OO 


2. O 


3.02 


I . IO 


12.05 


13.50 


3.05 




3.^0 


2.70 




3-45 


21 .; o 


42.OO 


20.85 


28.90 


41.90 






4- o 


3-l8 




23-55 


32. o 




39-75 


55.90 


71.00 


6.80 



PIPE COVERING, 85% MAGNESIA (NET) 





COST PER FOOT. 


COST FEZ. FITTING. 


Size 






Pipe. 


ii Ins. Thick. 


2 Ins. Thick. 


Elbows. 


Tees. 


Valves. 


I 


$O.I 3 


'$0.21 


$0.08 


$0.09 


$0.14 


2 


.16 


2 5 


.09 


. II 


15 


3 


.19 


.29 


.12 


14 


.16 


4 


.22 


34 


15 


.16 


38 




.28 


43 


33 


.40 


.70 


IO 


42 


.60 


.90 


I-I5 


i-5S 



COSTS OF INSTALLATION AND OPERATION TESTS 347 

Machinery Costs. These costs are made up of various items 
listed in the tables which follow. The prices represent average 
cost prices with discounts taken off. The items are for indi- 
vidual machines, but for complete equipment Mr. Thomas 
Shipley gives the following as a guide for the cost of ice plants 
per ton of ice-making capacity when they are at least of 50 
tons capacity. 

Compression can system $550 per ton 

Compression block system 650 

Compression plate system (direct expansion) 800 

Compression plate system (brine) 1000. 

Absorption can system 500 

The yield of these plants will be 7! to 10 tons of ice per 
ton of coal in distilled-water can plants, 10 to 35 tons in raw- 
water can plants, and 10 to 15 tons in plate plants. 

Refrigerating Plants. Cost of Mechanical Equipment: 

Plants of 50 tons and over. . . $150 to $300 per ton of refrigeration 

Plants of 8 to 20 tons 250 

Plants of 3 to 8 tons 300 

Plants of i to 3 tons 250 

Efficiency of Apparatus: 

Boilers 60 to 80% 

Producers 60 to 80 

Steam engines (indicated thermal) : 
Non-condensing : 

Simple . 6% 

Compound 10 

Unaflow it 

Corliss . 9 

Condensing: 

Compound . 20% 

Mechanical efficiency of engines 85 to 95% 

Steam turbines (overall thermal) : 

Non-condensing 6% 

Condensing, small 8 

Condensing, medium 10 

Condensing, large 21 

Gas and oil engines: 

Indicated thermal efficiency 25 to 35% 

Mechanical efficiency 85 

Compressors: 

Mechanical efficiency . . 85 to 95% 

Volumetric efficiency 88 



348 



ELEMENTS OF REFRIGERATION 



Fuels: 

Crude Oil: 

Heating value per Ib IQ,OOO to 20,000 B.t.u. 

Weight per cu.ft 5o Ibs. 

Cost per barrel of 42 gallons $1.5 

Gasoline: 

Heating value per Ib 20,500 B.t.u. 

Weight per cu.ft 5o Ibs. 

Cost per gallon 20 to 30 cts. 

Bituminous coal: 

Heating value per Ib 13,800 B.t.u. 

Weight per cu.ft., loose 5 Ibs. 

Cost per ton of 2240 Ibs. at mine $i . 55 

Cost of freight for 300 miles 1.9 

Anthracite pea coal : 

Heating value per Ib i3,4 B.t.u. 

Weight per cu.ft., loose 5 6 Ibs. 

Cost per ton of 2240 at mine $2 .65 

Cost of freight, 200 miles i . 60 

Anthracite buckwheat coal : 

Heating value per Ib 12,800 B.t.u. 

Weight per cu.ft 56 Ibs. 

Cost per ton of 2240 Ibs. at mines $i . 85 

Cost of freight, 200 miles i . 50 

BOILERS AND SUPERHEATERS. EFFICIENCY 65 TO 80% 
COST OF BOILERS 

BOILER HORSE-POWER (10 SQ.FT. PER H.P.). 
50 100 200 300 400 500 

Return tubular $ 760 $1120 $2000 $2800 

Water tube 1500 2300 3600 4700 $5700 $7500 

Superheaters, 10 to 15% of 

boiler surface for 100 to 

120 F. superheat 600 600 1000 1300 1500 1600 



PRODUCERS. EFFICIENCY 60 TO 80% 
COST OF PRODUCERS 



H.P 80 

Cost $1600 



IOO 

$1800 



150 

$2200 



200 
$2500 



250 

$2800 



3OO 4OO 

$3200 $3800 



Producers are based on 1.2 Ibs. of coal per hr. per H.P. Grate areas of size 
to burn 9.4 to 10 Ibs. of coal per sq.ft. per hour. 



COSTS OF INSTALLATION AND OPERATION TESTS 349 

ENGINES AND TURBINES 

Steam consumption of engines per I.H.P. hour: 

Simple non-condensing 24 to 40 Ibs. 

Compound non-condensing 2 1 to 36 

Compound condensing 14 to 20 



COSTS 
CORLISS ENGINES, SIMPLE (100 Ibs. per sq.in. gauge) 



Indicated H. P.. 20 


40 


70 


100 


150 


200 


300 


Size 


8X18 


10X30 


12X30 


14X36 


16X36 


18X42 


22X42 


Cost 


$1000 


$1200 


$1500 


$1900 


$2150 


$2700 


$3500 



CORLISS ENGINES, COMPOUND (125 Ibs. per sq.in. gauge) 



Indicated horse-power 


IOO 


600 




Size 


10 and 18X36 


20 and 36X42 


26 and 50X48 




Tandem 


Cross 


Cross 


Cost 


$3000 


$10,000 


$2O,COO 



HIGH-SPEED ENGINES 



Indicated horse-power. . . 


47 to 107 


75 to 162 


87 to 189 


107 to 240 


185 to 390 


Size 


10X10 


12X12 


13X12 


14X14 


18X18 


Cost, belted 


$755 


$980 


$1015 


$1260 


$2510 


Cost, direct connected . . 


IO2O 


1270 


1375 


1617 


3000 



Piston speed from 550 to 650 ft. per min. 
Steam pressure, 80 to 150 Ibs. per sq.in. gauge. 
Mechanical efficiencies, 85 to 95%. 
Steam consumption, 29 to 35 Ibs. per I.H.P. hour. 



TURBO-GENERATORS 



Capacity in K.W. 
Cost 


25 B.C. 

$1375 


ico B.C. 

$3800 


150 B.C. 

$53oo 


200 B.C. 
$6200 


zoo A.C. 

$4100 


200 A.C. 

*55o 



Steam consumption 40 Ibs. per K.W. hr. in small sizes to 26 Ibs. per K.W. hr. 
in large sizes. Both condensing. 



350 ELEMENTS OF REFRIGERATION 

GAS, GASOLINE, OIL OR PRODUCER ENGINES 



Indicated horse-power. . 


5 


10 


25 


50 


100 


200 


300 


Cost of gas' or gasoline 
















engine ....'...-.....'. 


$210 


$380 


$77 


$1500 








Cost of fuel-oil engine. . 






1900 


3100 


4600 


6800 


06OO 


Cost of engine and suc- 
















tion producer 






1800 


2800 


4700 


7000 


9800 



Add 15% for freight and erection of engine and producer. 

s-X -- ; < .-. '. 



ELECTRIC GENERATORS (B.C.) 

Efficiency 90 to 95% 



Capacity in K.W. 


25 


50 


75 


100 


150 


200 


Cost, belted 


$450 


$600 


$1000 


$1000 


$1500 


$2 200 


Cost, direct connected 


650 


875 


1150 


1400 


1850 


2400 



ELECTRIC MOTORS (B.C.) 
Efficiency 85 to 95% 



Horse-power 
Cost. . 


7* 

$213 


15 
$290 


25 
$45 


5 

$605 


75 
$7i5 


100 

$1225 


150 
$1290 


200 
$2403 



SWITCHBOARBS 
SWITCHBOARDS FOR B.C. GENERATORS 



Capacity in amperes 
Cost '... 


125 
$69 


250 

$78 


375 

$78 


500 

$87 


75 
$155 


1000 

$175 



Voltmeter, ammeter, rheostat, main switch and fuses. 



SWITCHBOARDS FOR A.C. GENERATORS 



Capacity in amperes 

Cost... 



$125 



200 
$15 



{Ammeter, voltmeter, exciter field switch, exciter and generator rheostat 
mounting, triple pole main switch and fuse.) 



COSTS OF INSTALLATION AND OPERATION TESTS 351 

AMMONIA COMPRESSORS 

Mechanical Efficiency 85 to 95% 



Capacity in tons of ice 
2-ton refrigeration = I ton ice. 


. . . . 2 . 


5 


10 


25 ; so 


IOO 


200 


Cost of compressor (belt drive) 
Cost of compressor and simple engine 
Cost of compressor and compound en 


. . . . 5550 

... . . 730 


$700 
1150 


$1150 
1800 


$1850 $3400 
2675 Sooo 
4550 6500 


$8,700 
10,670 
13,750 


$17,950 

21,160 

27,500 



AIR COMPRESSORS 

Mechanical efficiency of compressor and motor 85%. 
Efficiency of system from compressor motor to air motor 40%. 



Free air in cu.ft. per min 


55 


no 


250 


350 


Diam. steam cylinder, inches 


6 


8 


IO 


12 


Diam. air cylinder, inches 


7 


9 


12 


14 


Stroke, inches 


6 


8 


10 


12 


Price of engine compressor, governor and 










unloader 


$520 


$700 


$1080 


$1500 


Price of belt-driven compressor with un- 










loader : . 


270 


400 


640 


940 


Max. pressure by gauge in Ibs. per sq.in. . 


100 


IOO 


IOO 


IOO 



PUMPS 

Direct acting for boiler feed, brine, or aqua ammonia. 

Mechanical efficiency, 75%. 

Steam per I.H.P. hour, 100 to 400 Ibs. 



Gallons brine per minute 


IOO 


250 


500 


IOOO ' 


Size in inches for brine (Simplex) . 


6X6X7 


; 8X8X13 


12X12X20 




Cost 




Si 70 


$260 


$57 


$870 


Weight in Ibs 




800 


1660 


4900 8650 ' 


Boiler horse-power. . . 




90 


190 


425 


IOOO , 


Size in inches for 


boiler feed 








(Simplex) 




5X2^X6 


5X31X7 


6X4X12 9X6X13 


Cost 




190 


$IIO 


$150 $250 



CENTRIFUGAL PUMPS 



Speed 

Horse-power . 
Weight in Ibs. 
Cost without motor 



ute 


IOO 


250 


500 


IOCC 




1800 


1800 


2OOO 


1600 




7-5 


IS 


25 


50 




590 


725 


900 , 


1500 


otor 


$180 


$190 


$27O 


$33 


per sq.in 


IOO 


IOO 


IOO 


IOO 



352 



ELEMENTS OF REFRIGERATION 



AIR LIFT PUMP 
Mechanical Efficiency 40% 

FAN BLOWERS 
Mechanical Efficiency 60% 



Capacity at i oz. in 


















cu.ft. per min 


2000 


4000 


8000 


l6,000 


26.000 


40,000 


54,000 


72,000 


Diam. wheel in inches. 


15 


21 


30 


41 


S3 


64 






Cost 


$120 


$IQO 


$270 


$400 


$600 


$800 


$1150 


$1625 



BELTING 
Efficiency of Transmission 93 to 97% 



Cost per inch of width, single thickness 

Cost per inch of width, double thickness 



8| cts. sq.ft. 
17 cts. per ft. 



Ammonia Condensers, Coils and Fittings. Allow 5 to 
10 F. difference in temperature between water and vapor in 
saturated portion of condenser. Use 2-in. pipe for single-pipe 
condensers, 20 ft. long, and 24 pipes high in large stands, if -in. 
pipe may be used. 3-in. and 2-in. pipe are used in double-pipe 
condensers. Use K = 50 for superheated portion of condenser, 
100 to 200 for portion in which there is liquid on each side in 
double-pipe work; 60 is the value used in ordinary single pipe 
type of condenser. In the Block and Shipley forms of con- 
denser K = 2<x>. About 1 8 sq.ft. of surface is allowed per ton 
of capacity and it may be reduced to 8 sq.ft. where liquid 
ammonia is on the inner surface. 

Cost of double-pipe condensers of if- and 2-m. pipes 20 ft- 
long is given by: 

Cost per stand = $5 +$i 5 X number of pipes high. 

For 2 and 3-in. pipes, 20 feet long: 

Cost per stand = $30+$! 5 X number of pipes high. 

Cost of Condensers with pan is given below: 



Capacity in tons of ice 
















Cost for single-pipe condenser. . . . 
Cost for double-pipe condenser. . . 


$160 

100 


$220 
ISO 


$400 
250 


$900 
450 


5 
$1700 
850 


$325 
1700 


$6550 
3150 



COSTS OF INSTALLATION AND OPERATION TESTS 353 



" DE LA VERGNE " STANDARD COUNTER-CURRENT ATMOSPHERIC AMMONIA CON- 
DENSERS (Fie. 73) 



Number 
of Stands. 


Sq.ft. of 
Cooling 
Surface. 


Capacity 
Tons of Ice 
Melted per 
24 Hours. 


Length 
Over All. 


Width 
Over All. 


Sq.ft. of 
Floor Space. 


I 


222 


I2| 


23' 6" 


4' o" 


94 


2 


444 


25 


23' 6" 


6' o" 


141 


4 


888 


50 


23' 6" 


10' o" 


235 


8 


1776 


100 


23' 6" 


1 8' o" 


423 


16 


3SS2 


200 


23' 6" 


34' o" 


799 


24 


5328 


300 


23' 6" 


50' o" 


"75 



COST OF STEAM CONDENSER 
Allow i sq.ft. for 5 Ibs. of steam or design by Orrok's formula. 



Shell type sq.ft 


surface 


IOO 


200 


400 


800 


Cost 




$250 


$390 


$725 


$1280 



Sheet iron type, 7' o" high, 20' o- long. . 



$190 



Expansion Coils. Allow 275 sq.ft. of surface per ton of ice-making capacity 
in plate plants. Allow 300 lin.ft. of ij" pipe in can tanks per ton of ice 
for ordinary coil and 200 to 250 lin.ft. when flooded. 

Brine Coils. Allow 250 sq.ft. of surface per ton of ice in plate system. 

Brine Coolers. 



Tons of ice 


2 


5 


10 


25 


50 


IOO 


200 


Cost of double-pipe brine cooler . . 


$6 4 


$120 


$250 


$500 


$1000 


$1950 


$3900 


Cost of triple-pipe brine cooler . . . 


2 2O 


310 


375 


75 


1500 


3000 


6OOO 


Cost of shell-and-tube brine cooler 




ISO 


200 


360 


650 


1250 


2500 



Ammonia Separators. 24"X36" welded. 
Ammonia Receiver. i2"X72" welded. . . 



$125 
65 



354 



ELEMENTS OF REFRIGERATION 



PIPING AND FITTINGS 

[List price given.] 



Size. 


PIPE. 


ELLS. 


TEES. 


Std. 


Ex. Hvy. 


Std. 


Ammonia. 


Std. 


Ammonia. 


Screw. 


Flange. 


Screw. 


Flange. 


gjE 

H;;;;;;;;; 

2 

3 
4 
6 

Discount . . . 


$0.06 
.o8J 
.} 

.17 
.23 
.371 

a 

i.op 
1.92 

75% 


$o.07i 
. ii 
IS 

.22 

-30 
-36i 
SOi 
1.03 
I 50 
2.86 

70% 


$0.05 
.06 
.08 
.10! 
.16 
. 20 


$0.55 
.65 
.75 
.90 
i . 20 
i-SO 


$1.05 
1.30 
i. 60 

2. IO 

2.45 
2.70 


Io.o8 
.09 

.12 

.15 
.23 
-29 


$0.80 
.95 

I . IO 

i.3S 
1.75 
2.30 


$ .80 

.10 

.40 
.70 
.00 
.50 
.80 
i .60 
31.00 
48.00 

70% 


.75 

1.20 

2.75 
70% 


5. 10 
11.40 

'70% 


2O.OO 
40.00 

70% 


1.75 
4.00 

70% 


7.. 80 
17'. 10 

70% 





FLANGES. 


RETURN BENDS. 


VALVES. 


Size. 


Pairs. 




Ammonia. 


Ammonia. 




Std. 


Amm. 




Screw. 


Flange. 




Screw. 


Flange. 






$i .00 








$1.01 


$7.50 


$7-40 





0.40 


i . 20 








1. 60 


8:50 


8.40 




.46 


i. 60 


|0.26 






2. 20 


9.50 


9-75 


i 


-52 


i. 80 


.30 


$0.95 




2.80 


10.50 


1.15 


a 


.64 


2.45 


.40 


1.30 


2.80 


4.00 


13.00 


7-95 




-78 


2.95 


55 


2.25 




5-50 




9-45 


2 


1 .00 


3.60 


.80 


2.00 


5.20 


8.75 




3.10 


3 


1.50 


6.00 


2. 2O 






12.50 




2.50 


4 


2.10 


n .20 


6. 50 






19.00 




84.00 


6 


3-95 


20.00 








37.50 




159.50 

















COSTS OF INSTALLATION AND OPERATION TESTS 355 



3 

II 

O 3 
g ^ 
" 



58 



'>** o c 3 



|y 

O.SR ^ 



ll! 



SJ? 



1-9 



B-S 

M 



1| 

c^ 






O M M TfsO O\O >O vO O\ ^ (N IN 

OOO OOO"HN ro *t\O 00 O 






t^oS ^ I 



> w r-oo r^ sC 



) ^t 'O fO 

. O r-oo 
) 1/10 t> 



OnO'-'OO OOOO 



MO'-'vON i-HWC\'^'O CN^^r-T}- COOO 



OO w r- O O 






I-H o\ fO "^ 10 -^f ^t t^-vo r^o O M ^ "^"^O 

g O H ^2"2"^g wSSciw 'S^fo $> 



356 ; ELEMENTS OF REFRIGERATION 



a o 

~ I 
B fi 



g* 



s - 



HI 

w w 



IP 



<u i 
G i. u 

in 



rnal 
hes. 



(JOJ^^t;. M < 



M OOO.O>t-t^ OOrJ-OiNO 
M OOiOON OWCMiO 

ci ro 4-d t^. . a o M 



<V M 0>- 



wN woo 



tual 
ernal 
hes. 



11 2 



?l5 2ui 

inn 



*tl/5 NOOO toOO 

t- ^tO W ^t O -O to t^- "** 


PO O 


5^?^" < 

O lorom IOMVO * 
JO O.-O T ro M M' M 


l 


SsIIs llisf 


t^- r~ 

S K 










a^ssssass 


SS 




M M 


mi, !!!g 


100 


*vOOO *! N M -* 


N 


:-SSi^^ 


Tf -<t 






Hl^lE^p 


^ 


IISslislIB 


t^. ro 

t". 


M M 


w (S 


o | 1 l+l 


^ 


Hill Hill 


IO 

IO t^ 

t^-00 


Bi i?^ 


is 






lO 1OO 


II 






_ _ ^ ^ 









* 

I 
g 

I 



COSTS OF INSTALLATION AND OPERATION TESTS 357 

Piping for Ice Storage Rooms: 



Capacity in tons of ice 


2 


e 




2C 








Cost 


$75 


$IOO 


$150 


$200 


$350 


$450 


$750 



CANS AND DISTILLING APPARATUS 

Allow twelve 3oo-lb. cans per ton for flooded system, otherwise fourteen 
300-lb. cans. 



Capacity in tons of ice.. . . 


2 


5 


10 


25 


50 


100 


200 


Cost of cans and tank with 
















coils, raw water 


$950 


$1400 


$1950 


$3850 


$6850 


$13,250 


$26,IOO 


Cost of cans and tank with 
















coils, distilled water 


550 


900 


1600 


3200 


5750 


11,400 


22,90O 


Distilling apparatus 


400 


500 


600 


IOOO 


1650 


2,500 


4,400 



Reboilers, 6o"X6o" $100 

Skimmers, 20" X 1 20" 4 

Water coolers of i% and 2 ft. pipe, 20 ft. long. Same as double- 
pipe condensers. 
Sponge filters, 9"X42" $35 



MISCELLANEOUS APPARATUS AND SUPPLIES 

Agitators. 12" belt driven $ 3 6 

8" motor and agitator 200 

Can Fillers: For 3oo-lb. cans $ J S 

Can-filling hose 4 cts. per ft. 

Can hoists, 300-lb. cans: 

Electric $5 

Air 200 

Hand 75 

Ice dump, 300-lb. single 5 

300-lb. double 9 

Ammonia 25 to 30 cts. per Ib. 

Carbon dioxide 5 cts. per Ib. 

Sulphur dioxide $i per Ib. 

Calcium chloride $14 per ton 

Sodium chloride $14 per ton 

Water from city 5 to 20 cts. per 1000 gal. 



358 



ELEMENTS OF REFRIGERATION 



51 



III 



A'a 



V WtVwb V- 



b o 
b "- 



js MVO - 



xxxxx xxxxx xx 



,7^ 



ob 



-o^o^r 2 ~ 



> O "V~ oo 'b "N 



OO iOiOOO 

M c< foo Ov N 



COSTS OF INSTALLATION AND OPERATION TESTS 359 





T 



FIG. A. York Compressor. 



360 



ELEMENTS OF REFRIGERATION 



PARTICULARS OF " DE LA VERGNE " STANDARD HORIZONTAL AMMONIA 
COMPRESSORS 

ONE COMPRESSOR WITH SIMPLE ENGINE AND Two COMPRESSORS WITH COMPOUND 

ENGINE 



Capacity, tons of ice melted 
per 24 hours * 
Diameter compressor cylinder, 
ins 
Diam. steam cylinder, ins. . . . 
Stroke, ins 
R.P.M 
Rated H.P 
Dimensions main bearings, ins. 
Diameter crank pin, ins 
Diameter cross-head pin, ins. . . 
Steam pipe, ins 
Exhaust pipe, ins 


25 

IS 
18 
63 
45 
6iXn 
4i 
3 
3 
4 


35 

Hi 

17 
2O 

65 

60 
7Xi2i 

i ! 


50 


75 


IOO 


125 


ISO 


200 


19 

22 
62 

85 

8 XiS 
Si 
4 

4 
6 

3 


20 
26 
68 
130 
9XiS 
si 
4i 

t 


22 
30 
65 
170 
IOXl8 

6 

4i 




26 

II 
215 

IlX2( 

f 

7 


26 
33 
56 
255 
12X22 

P 

8 
S 


32 
36 

57 
340 

T 

9 
S 
5 
1 60 
19,000 

# 

10' o" 


Diameter flywheel, ins 
Weight, do, Ib 


96 
5000 


105 
6000 


1 2O 
7000 


128 
9000 


136 
10,500 


144 
14,00 


1 60 

) 17,000 


Width over all 
Height above floor 


8' 6" 
6'o" 


8' 9" 
6' S " 


9' 6" 
7' i" 


11' o" 

7' 7" 


11' 2" 
8' 2" 


1 2' 6" 

9' 3" 


1 2' 6" 

9'S" 




Capacity, tons of ice melted 
per 24 hours * 
Diameter compressor cylinder 
ins 
Diam. steam cylinder, ins 
Stroke, ins 
R.P.M 


250 

24 
34 
40 
54 
425 
14X28 
9 

si 

7 
10 
6 
5 
174 
23,000 
29' o" 
1 6' 6" 
10' 7" 


300 

26 
36 
48 
45 
5io 
16X2* 
9i 

1 
10 
6 
6 
192 
4o,oo< 

33 ; o;; 

1 7' 6" 

II' O" 


2SO 


300 


400 


500 


600 
2-26 

34&6S 
48 
45 
1050 
20X36 
IS 

1 
20 
9 
8 
216 
50,000 
47' 4" 
13' H" 
12' H" 


2 4 & 4 8 

33 

58 
440 
14X28 

12 

4i 
S 

6 4 
5 
160 
) 19,000 
34' 5" 
12' 6" 
10' 8" 


27&S4 
33 
56 
525 
IS X28 

'si 

6 
IS 
6 
5 
160 
23,000 
38' o" 
12' 6" 

II' 0" 


29&S8 3 
36 
57 
700 
17X30 
13 
Si 
7 
16 
7 
6 
T 74 
26,000 
40' 2" 
12' 8" 
n' 7" 


2&64 
40 

IT'S 
18X34 

'si 

7 
18 
8 
7 
192 
40,000 
43' 4" 
13 o 
13' o" 


Rated H. P. 
Dimensions main bearings, ins. . 
Diameter crank pin, ins 
Diameter cross-head pin, ins . . . 
Steam pipe, ins 
Exhaust pipe, ins 


Ammonia discharge, ins 
Diameter fly-wheel, ins 
Weight, do. Ib 
Length over all 
Width over all 
Height above floor 



* The ice-making capacity of these machines is from 50 to 60% of this rating. 




FIG. B. De La Vergne Compressors. 



COSTS OF INSTALLATION AND OPERATION TESTS 361 







spunoj 'aiajd 




g 


a 
z 


Si 


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puB aossaaduiOQ 


"^^^^s,?:- 


2 

o 


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p 

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saqoui '^H^PH 


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saqoui 'q^3ua^ 


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362 ELEMENTS OF REFRIGERATION 

DATA FROM HIGH-SPEED ENGINE ERIE CITY IRON WORKS 











Weight 












Size of 


A 


B 


c 


of Fly- 


D 





F , G 


// 


/ 


Engine. 








wheel. 












10X1 


Ins. 
4 


Ins. 

48 


Ins. 

9i 


1345 


Ins. 
isi 


Ins. 
18 


36 28 


75 


Ins. 
103 


ii Xi 


4 


48 


9i 


1345 


15 i 


18 


42 ; 30 


75 


105 


12X1 


Uf 


54 


13} 


2025 


i8J 


22J 


48 


30 


90 


120 






















14X1 
iSXi 


5. 


60 


14 J 


2920 


aii 


26J 


54 


36 


105 


131 


16X1 
17X1 


7 


72 


I6J 


4500 


24* 


29i 


60 


40 


1 20 


1 60 


18X1 
19X18 


8 


72 


18} 


5200 


27| 


39* 


66 


48 


131 


179 


Size of 
Engine. 


J 


K 


L 


M 


N 


Speed. 


Initial 
Steam 
Pressure. 


I.H.P. 




Ins. 


Ins. 


Ins. 


Ins. 


Ins. 








10 Xio 
ii Xio 


85 
91 


25* 
25J 


54* 

60 i 


99 
99 


11 


300 to 350 

oo to 350 





47 to 104 
57 o 126 


12X12 
13X12 


108} 


30? 


72i 


117 


61} 


75 to 325 
75 to 325 


a 


75 o 162 
87 o 189 


14X14 
15X14 


130* 


351 


80 J 


135 


7i'. 


50 to 300 
50 to 300 




107 o 240 
123 o 273 


16X16 
17 Xi6 


I34l 


40 1 


89i 


ISO 


8ii 


25 to 275 
25 to 275 





146 o 333 
165 to 370 


18X18 
19X18 


148 


47 J 


105* 


167 


921 


200 to 225 
200 to 225 




185 to 390 
205 to 435 




FIG. C. Erie City Iron Co. Engines. 



COSTS OF INSTALLATION AND OPERATION TESTS 363 
DATA FOR TURBO GENERATORS 



Power. 


R.P.M. 


Width. 


Length. 


Limit 
Length. 


Height. 


Steam 
Pipe. 


Exhaust 
Pipe. 




K.W. 




Ft. Ins. 


Ft. Ins. 


Ft. Ins. 


Ft. Ins. 


Ins. 


Ins. 




35 


D.C. 3600 


2 IO 


6 6 


7 II 


3 oj 


2 


4l 


Non- 


100 

200 


A.C. 3600 
D.C. 3600 


4 10 
4 4& 


12 4J 

12 4! 


12 IlJ 

12 4i 


4 9 
4 iij 


it 


8 
8 


condensing 


200 


A.C. 3600 


5 o 


II 9l j 13 io| 


4 9 


3* 


8 










1 


I 







DATA FOR RETURN TUBULAR BOILERS 





Shell. 


Tubes. 












Boiler 
H.P. 


Diam. 


Length, 


Diam. 


No. 


A 


B+K 


c 


C' 


D 


E 




Ins. 


Ft. 


Ins. 




Ins. 


Ft. Ins 


Ft. Ins. 


Ft. Ins. 


Ft. Ins. 


Ft. Ins. 


46.5 


42 


5 


3 


34 


42 


16 2 


2 




8 5 


7 9 


65.4 


48 


5 


3 


50 


48 


16 2 


2 


i ii 


8 ii 


8 I 


80. i 


54 


5 




62 


54 


16 2 


2 


2 2 


9 6 


8 9 


98.7 


60 


6 




72 


60 


17 2 


3 


2 I 


o o 


9 I 


131.9 


66 


8 . 


; i 


74 


66 


19 6 


3 


2 3 


o 8 


9 8 


197. i 


78 


8 


I 


H4 


78 


19 8 


6 


2 6 


2 7 


O IO 


242 . o 


84 


8 


^ i 


142 


84 


19 8 


6 


2 6 


2 IO 


i 3 


283.0 


90 


8 


. i 


168 


90 


19 10 


6 


2 6 


3 4 


i 8 


313.7 


96 


8 


3i 


190 


96 


19 10 


6 


2 6 


3 10 


2 I 


354-6 


96 


o 


3i 


190 


96 


21 IO 


6 


2 6 


3 10 


2 I 


391-6 


96 





3 


248 


96 


21 10 


6 


2 6 


3 10 


2 I 






















c to c 






Boiler 
H.P. 


F 


Gfor i 
Boiler. 


H 


I 


J 


K 


L 


M 


N 


Shells 
in Bat- 


Red 
Brick. 


Fire 
Brick. 






















tery. 






46.5 


Ft. In 
19 


Ft. Ins 
8 o 


Ins 
33 




40 


2 


43 


37 


3 


48 


i Ft. Ins 
5-8 


15.000 


1300 


65.4 


19 


8 6 


33 




48 


6 


49 


43 


4 


54 


6-2 


16,000 


1525 


80.1 


19 


9 o 


33 




48 


6 


55 


49 


4 


60 


6-8 


16,700 


1650 


98.7 


2O 


9 6 


33 




48 


6 

Al 


61 

67 


I 5 


4 


66 


7-2 


18,200 


1900 

2IOO 


131 -9 
167.5 

197 . I 


22 
22 


10 6 

II O 


33 
33 
33 




5 

5,2 

54 


1 


73 
79 


67 
73 


6 
6 


78 8-2 
84 8-8 


23,000 
24,000 


25OO 
2625 


242.0 


22 


ii 6 


33 




54 




85 


79 


7 


90 


9-2 


26,000 


285O 


283.0 


22 


12 


33 




56 


7 1 


91 


85 


7 


96 


9-8 


28,000 


3050 


319.7 


22 12 6 


33 




56 


7t 


97 


91 


8 


IO2 


10-2 


30,000 


3400 


354-6 


24 12 6 


33 




56 




97 


91 


8 


IO2 


IO-2 


32,000 


3400 


391-6 


24 12 6 


33 




561 


71 97 


91 


8 i IO2 IO-2 


32,000 


3400 



Other size boilers are made between the sizes given by vai 
and by changing size and number of rows. The thickness of s 
pd = 2tS x eff. 



; length from 14 to 22 ft. 
is given by the formula 



364 



ELEMENTS OF REFRIGERATION 




COSTS OF INSTALLATION AND OPERATION TESTS 365 

WATER TUBE BOILER DIMENSIONS 



Boiler H.P 


75 


ICO 


200 


300 


400 


500 


Columns and 
Rows of 4" 
flues 


5-9 


6-9 


io-9 


i6-g 


16-12 


21-12 


A and number 
of drums 
B 


36" i 
19' o" 


36" i 
i 8' 4 f" 


3 6" 2 
20' 4 " 


42" 2 
20' 4" 


42" 2 
20' 4 " 


42" 3 
20' 4" 


C 
D 


8' 2" 
3' 2 " 


8' 2" 
3' 2 " 


8' 2" 
3' 2" 


8' 2" 
3' 2 " 


8' 2" 
3' 2 " 


8' 2" 
3' 2 " 


E 


4 i" 


4 i" 


4l" 


45" 


4l" 


45" 


F 
G 
H 
/ 


30" 
7' 5" 
14' 8" 
13' o" 


39f" 

7' 5" 
14' 8" 
13' o" 


39f" 
7' 2" 
14' 8" 
13' o" 


39f 

7' 2" 
15' 2" 
J 3' 3" 


39!" 
9' 2" 
17' 6" 
15' 7" 


39!" 
9' 2" 
17' 6" 
15' 7" 


j 


6' o" 


6' o" 


6' o" 


6' o" 


6' o" 


6' o" 


K 


2' 3*" 


2' 35" 


2' 3i" 


2' 3s" 


2' 3i" 


2' 3\" 


L 
M 
N 
O 


15" 
6' 4" 
17' 95" 
10' 9" 


15" 
6' 4" 
17' 9?" 
n' n" 


15" 
6' 4" 
19' 9" 
17' 2" 


15" 
6' 4" 
19' 9" 

24' 2" 


IS" 
8' 2" 
19' 9" 
24' 2" 


15" 
8' 2" 
19' 9" 
30' o" 


p 


16" 


1 6" 


1 6" 


16" 


16" 


16" 


Q 

R 
5 
T 
U 


6' o" 
24" 
8" 
17" 
3' 3" 


6' o" 

24" 
8" 
17" 
3' 10" 


7' o" 
24" 
8" 

I7"&2 4 " 

6' 2" 


7' o" 
24" 
8" 
i7"& 24" 
9' 8" 


7' o" 
24" 
8" 
17" & 24" 
9' 8" 


7' o" 
24" 
8" 
17" & 24" 
12' 7" 


W 


9" 


9" 


12" 


12" 


15" 


IS" 


X 


15' 5" 


15' s" 


15' 8" 


16' 2" 


17' n" 


18' 9" 



ELEMENTS OF REFRIGERATION 





--. 



___ 



COSTS OF INSTALLATION AND OPERATION TESTS 337 

ANTHRACITE SUCTION PRODUCERS. DIMENSIONS 



H.P. 


B 


C 


D 


E 


F 


G 


H 


K 


Width. 


Height. 


100 
200 

300 


5 ', *",, 

7' 2 " 
8' 8" 


n'8" 

12' 8" 
15' 3" 


39" 
4' 6" 
3' 5" 


3' 3" 
4' 8" 
5' 8" 


14' o" 
1 8' o" 

20' o" 


6' 6" 
?' o" 
8' 9" 


7' 2" 
Q'O" 
10' 7" 


5' 4" 
6' 3" 
6' 8" 


13' o" 

15' o" 
17' 6" 


20' o" 
21 ' o" 
26' 6' 


400 


9' 8" 


16 o 


3 5 


6' 6" 


20 o 


9 3 


n' 8" 


7 i" 


18' 6" 


26' 6' 




FIG. F. Gas Producer. 



ELEMENTS OF REFRIGERATION 



DIRECT-CONNECTED GENERATOR 
DIMENSIONS (Inches) 



K.W. 


Speed. 


Poles. 


B 


c 


D 


A 


E 


F 


G 


H 


/ 


2 S 


280 


6 


42* 


34f 


IS* 


4 or 4! 


i8i 


39 


IQ* 


18} 


i6f 


5 


260 


6 


48* 


37A 


i Si 


4i or 6 J 


21 


44 


"A 


!9| 


19 


75 


250 


6 


54! 


43 H 


J 9 


Si or 74 


22| 


5i 


24H 


f 


21 


100 


235 


6 


60} 


46| 


19 


6or8| 


22} 


56 


27* 


24 


23? 


15 


200 


8 


68| 


sal 


22 


7 or 10 


24 


64i 


3if 


25 


27? 


200 


180 


8 


?4l 


S9l 


25 


8 or ii 


26 


7i 


34l 


2Qi 


29 


300 


150 


10 


88 


66i 


25 


10 or 13 


27 


85} 


4ii 


3ii 


31* 


400 


150 


10 


101 


76 


28 


15 or 17 


30 


IOl| 


48 


34} 


35 




FIG. G. Generator. 



COSTS OF INSTALLATION AND OPERATION TESTS 369 

MOTOR DIMENSIONS (Inches) 



H.P. 


Speed. 


Poles. 


A 


B 


C 


D 





F 


C 


20 


800 


4 


S2A 


34i 


26! 


3l! 


15 


25^ 


28 


5 


650 


6 


62* 


45 


36 


43 


21 


26^ 


28i 


80 


600 


6 


75* 


52 


42| 


49H 


24 


31 


361 


IOO 


575 


6 


go* 


58* 


46i 


52^6 


24 


35i 


361 


125 


55 


6 


93f 


62 


5i 


57l 


27 


36f 


371 





FIG. H. Motor. 



370 



ELEMENTS OF REFRIGERATION 



Power and Performance of Plants. Auxiliary Power. The 
power used by auxiliaries in a plant may be estimated from the 
following tables from which proportions may be found. 

The power used in a loo-ton compression plate plant 
is given in the Transactions of the American Society of Refrig- 
erating Engineers. 



By By 

jH.Torrance, Jr.| T. Shipley. 



i H.P. Compressor 




300.00 


220 


Water pump belt driven 1 1 . 6 net 


20.46 actual . . 






Agitator 4.3 


6.60 






Thaw pump 0.3 


0-53 






Boiler pump 0.98 


1.71 






Air vacuum pump 


3-3 




3 


Electric lights 


IO.OO. ....... 






Electric crane 


4.80. ....... 






Electric motor on cutting table . . 


3-63 


51-03 





Auxiliary power in per cent of main power 17% 

Steam per horse-power hour 18 Ibs. 

Actual evaporation in boiler per Ib. of coal 8.8 Ibs. 

8.5X2000X100 
Fenormance : - tons ice per ton coal 11.2 



15% 



10 to 15 



- - 
351 X 10X24 

The following data are taken from an electrically driven 
raw-water plant of 200 tons capacity: 

Compressor motor ................... 600 H.P. 

i2oo-gallon cooling- tower pump motor . 50 

i6oo-gallon brine-pump motors ........ 100 

i2oo-cu.ft. air-compressor motor ....... 30 

Core-pump motor ..................... 5 

Eight agitator motors ............... 24 



209 H.P. 

Auxiliary power in per cent of main power 35%. 

Air used. % to 1.8 cu.ft. free air per minute per 3 oo-lb. can. 

From a plant reported by W. H. Doreman, in Ue and 
Refrigera'io: for April, 1915, the following data are given: 



COSTS OF INSTALLATION AND OPERATION TESTS 371 

Total horse-power per ton 3.7 

Main motors 81 . o% 

Water pumps 7.2 

Brine pumps 3.7 

Air pump 1.8 

Pressure air pump 2.7 

Cranes 0.4 

Agitators 4.2 



100.00 

To operate a 150- ton ice plant electrically would cost about 
the same as to operate by compound steam engine with power 
at i cent per K.W., the saving in labor being made up by the 
increase in the power cost. The investment would be $20,000 
less and 20% of this would represent an item of $4000 in favor 
of the electric drive at this unit cost of i cent. 

Steam for Auxiliaries. The steam used per twenty-four 
hours in a ico-ton plate plant has been given by I. Warner 
in the Transactions of the A. S. R. E. 

Compressor engine 125,703 Ibs. 69 .6% 

Auxiliary engine and pump 45>347 2 5 2 

Dynamo engine ( 1 2\ hrs.) 5,152 2.8 

Harvesting 26 cakes 3,088 i . 7 

Melting off plates 1,290 0.7 

180,580 Ibs. 100.0% 

8.5X100X2000 

Performance: - = 9.4 tons of ice per ton of coal. 

180.580 

Power and Performance of Absorption Plant. The power 
used in an absorption plant with plate ice is 58.33 I.H.P. per 
100 tons capacity. The steam used is 27 Ibs. per I.H.P. hour. 
The generator requires 50 Ibs. of steam per hour per ton of 
capacity under usual conditions according to H. Torrance, Jr. 
The total steam needed by pumps is 5 8 -33.X 2 7 = I 575 Ibs. per 
hour. The total amount needed by generator is 5000 Ibs. per 
hour. The exhaust from the pumps could be used in the gen- 



372 ELEMENTS OF REFRIGERATION 

erator. The radiation from the pumps may amount to one- 
third of the steam supplied or 525 Ibs. of steam. This is lost. 
The remaining 1050 Ibs. may be used, requiring 5525 Ibs. per 
hour. The performance is 

8.5X2000X100,^ g tons of ke per ton of coal> 
5525X24 

Torrance suggests operating an absorption plant with the 
exhaust from a compression plant. Using figures above and 
assuming 25% of the steam from the compression plant con- 
densed by radiation, the steam returned would be 

351X18X0.75 =4740 Ibs. 
The amount condensed would be 

4740 X - = 1580 Ibs. 
-75 

The amount consumed would be 

4740+1580+1575 = 7895. 

The performance of the two machines together would be 
8.5X2000X200^ tons Qf ke ton Qf coal 

7895X24 

Performance of Producer-driven Plant. A test of a pro- 
ducer plant for 144 hours reported in ithe transactions of the 
A. S. R. E. by E. W. Gallen Kamp, Jr., showed that 22.10 
tons of ice were produced per ton of coal excluding auxiliaries 
or 17.8 tons with auxiliaries. A performance of 25 tons has 
been reported. 

Labor Costs. The tables on pp. 373 and 374, arranged from 
averages of estimates given by a number of manufacturers, may 
be used to estimate the probable number of men and cost of 
labor: 



COSTS OF INSTALLATION AND OPERATION TESTS 373 





g 


OOOOOOOO1/5O 
OOOOOOOONio 


88 






sninsssj 


^ U 







oooooooooo 
o o o wo o o o Co 


S,^, 






ii^ii 1 ' i ii 


5 














a88S8888SS 


^ 




** 


1 ' i i ' ' ' ' ' ' 





9 








H 


* 


OV50t-OOI^l?l^ 


a 5- 


O 




1 1 1 1 1 1 1 1 1 


s 


M 








Pi 

O 
55 


% 


a88K88K : : : 

i i ? 7 ? ? T ' 


o-o 
o o 


8 






J ' 


>< 

< 


10 


S^ : : : : : 


1O 1O 


a 




i i i i i .... 


w 


g 








)NS OF ICE P 





o o o in 
100 r- 


100 

od 


H 


? 


o 10 o 10 ' '.'.'.'. 
Till- 


S^ 

s' 




o 


-" ! ! ':':'' 


t^>0 

od 




u, 


i i V 


a^ 

M 




















c 

s 


llESgg- ' 2 ^ 

.s.S5 5 a a u u s s 

illl.p||| 

WWHhi65iJJ 


Total 
Labor cost per ton . 










S88888KK 

io4ciciNi-<>-i 



i-i O 


1 








1 1 1 1 I 1 1 1 


N 


ti 












> 








: 


O t^ 


1 






IH 


rf Tf W* C-i N oi ^ 


o d 


2 












o, 








: 


* 


| 








ssgg^i 


88 


i 






^ 


7???77 : : 


i O 


1 










w 


(D 








obo^u,: : 


o * 


1 






o 


???77: i 


2 


1 
















z 






8S8K : : : 


w 


s 


1* 




rO 


T ? T 7 


d>d 


a 


Q S 










j5 


* 







o 10 


IOCSO 


a 
'S 


H < 




<N 


if;; ; ; 


4d 


c 


C/) t^ 


SB 






%% 


1 


z < 






10 




1 


1-1 

PL| H 









1^5 


5 


o a 






i i : : : 


5 


1 


g 












a 
1 1 




10 


O 10 


jo 


d 








1 i ... 


^t o 


PJ 


w a 








M 


a 


P4 




o 


O 10 


t^ r 


11 








i M : : ; 





S^ 












gs 








ojo ::: 


KS 


Is 






"> 


77 ; ; ; 


^ 


0*w 












II 












he tables ab 
men from ti 











:| 


SI 






2 


>.|>,4 '% 


:& 


1 

U (4 








liilii' 3 - 


3 


O u 

^^J 








illllfe'U 


^i 


'5 








wwEE5o>-w 


5 


| 



374 



ELEMENTS OF REFRIGERATION 



COST OF FUEL AND SUPPLIES PER DAY 





TONS OF ICE PER 24 


HOURS 








S 


10 


IS 


20 


25 


35 


50 


75 


IOO 


200 


Fuel cost at $3 per ton 


.V2.S 


6.50 


9-50 


I2.OO|I3.OO 


16.00 24.00 


34-00 


43.00 


78.00 


Oil at 4 cts. per gal 
Electricity at 2 cts. per K.W. 


3.20 

8.80 


4.20 
16.80 


4.80 
19. 20 


4.40 

17.00 


5.00 
20.00 


7.00 10.00 i4.oo ; 2O.oo 40.00 
28.00 4o.oojs6.oo 80.00 160.0 


Oil, waste, etc 


-SO 


.75 


i .00 


I . IO 


i. IS 


i-45 


1.90 


2.75 


3-75 


7.25 

























Cooling Water. Starr in Ice and Refrigeration for 
Sept., 1911, points out that the head pressure increases when 
the quantity of water is decreased. This increases the cost 
of compression but decreases the cost of water and the cost of 
pumping water. There may be some point at which the com- 
bined cost of compression, water and pumping water is a mini- 
mum. This point will vary with cost of water, lift of water 
and cost of compression. This should be investigated for any 
given problem. 

Cost of Water. B. C. Sloat in Ice and Refrigeration for 
Dec., 1910, gives the following costs of pumping water per 
loco gallons: 



300 
10.3 



Head lifted, feet 50 100 

Deep- well pump 1.7 cts. 3 . 4 

Air-lift pump 1.2 3.6 

Displacement pump 0.85 ct. 2.3 

Cities charge from 5 to 20 cts. per 1000 gallons for water. 



Cost of Supplies in Ice Plant. Ice Plant of Moderate Size 
by Charles Dickerman in Transactions A. S. R. E v 1908. 



Year. 

1904 
1905 
1906 
1907 

Avera 


Total 
Tons. 


Tons per 
Day. 
300 Days. 


Cost Coal. 


Wages. 


Supplies. 


Repairs. 


Improve- 
ments. 


General 
Expenses 


6667 
8720 
9144 
8866 

ge per 


23 

29 
30 
30 

ton 


$1321.08 
1550.16 
1481.15 
I377.0S 


$4749-90 
4677.70 
5398.55 
5204. 19 


$1266.72 
936.64 
837.25 
887.51 


1354.40 
823.14 
1075.36 
933.8o 


$1352.02 
756.46 
301.15 
556.00 


$ 679.23 
1614.48 
604. 26 


$0.172 


$0.600 


$0.118 


$o. 125 


$0.089 


$0.087 



Total cost per ton exclusive of overhead charges 

Receipts per ton at plant 



$i .19 
$1.50 to $8 



COSTS OF INSTALLATION AND OPERATION TESTS 375 

Data from plant: 

Capacity, 30 tons. 

Compressors, two 13X30 vertical. 

Condensers, double pipe, 2 and 3-in. six banks, 12 high, 18 ft. tubes. 

Brine tank, 24 coils 2-in. pipe, 6 high, 44 ft. long, 6336 ft. 

Ice cans, 483 cans, 300 Ibs. 

Two bulkheads and two engine-driven agitators in tank. 

Fore cooler i2-in. diam.Xi6 ft. long. 

Ice house, 60 tons capacity, cooled by brine. 

Boiler, 66-in. return tubular, 18 ft. long. Fortyeight 4-ia. long. 

Stack, 3o-in., 125 ft. high. 

Bituminous coal, $2.40 to $2.50 per ton. 

Water, 3 cts. per ton of ice. 

Ammonia, $150 to $200 per year. 

Performance, 6| tons of ice per ton coal. 

Cost of labor, fuel and supplies at a plant in Asbury Park was 85 cts. per ton, 
one-half of which was labor cost. 

Load Factors. The load factor sometimes assumed covers 
one-third year at full capacity, one-third year at half capacity 
and one-third at quarter capacity. This gives 



Load factor o . 583 = 58% 

Nordmeyer suggests that the operation at full capacity 
for July with no storage capacity represents 15% of year's 
demand (use of ice in July equals 15% of total yearly amount) 



i 



Load factor = - = 0.56 = 56%. 

With storage space the plant may be run at full capacity 
for even the whole year. Of course the cost of storage is 
offset partially or completely by the smaller fixed charges on 
the smaller equipment. 

Cost of Storage. W. E. Parsons states that it cost 25 cents 
per ton to store ice, hold it from spring until midsummer and 
remove it to delivery platform in a 75-ton plant. J. N. Briggs 
increases this to 45 cents per ton to cover the charge for the 
storehouse. 



376 



ELEMENTS OF REFRIGERATION 



yi g 
r> v 

u 

O fc 

1 









O O 


O -fr 


1 


S 


-1 


5 


fi 


<j 


9 


00 


a o. 


H 


J 

W 


8 


52" 


"2 o 


g 


e 


00 


a oo 




1 


1 


4 r: M 


v/ '-// 






- 





s a 


1 


O 


*t 


S, "' H 




S 


| 


10 


r5 0. 


i 


a 


a o 5? 


1^ 00 




en 


i 


5 ~ 


2 5 


IS Tons. 


d 



1 


g s g 


* 

00 -O 

W* ** 


| 
1 


s 


g g g 


xO 


i 





s 


s s 




CO 


** 


5 * M 


S 






g 





10 M 


10 Tons. 





v? 


5 " 


fi 


Electric. 


t% 


ass 


o 5 


g 


o 


a s 


S" 




en 





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COSTS OF INSTALLATION AND OPERATION TESTS 377 



COSTS OF IOO-TON ICE PLANT 

By W. T. Price, in Ice and Refrigeration for Dec., 
INVESTMENT 





Steam 
Plant. 


Oil 
Engine 
Direct. 


Oil 
Engine 
Belted. 


Producer 
Gas. 


Engine and compressor 
Freezing system 
Ice-storage piping 
Building. 


{27,000 
27,000 
1,500 


$ 34,000 
27,000 
1,500 


$ 38,000 
27,000 
1,500 


$ 39,000 
27,000 
1,500 


Land ' 


9,500 


8,700 


9,100 


10,000 




$102,000 


$100,200 


$106,600 


$112,500 



OPERATING COSTS 



Coal $3.51 per ton with 8 : i boiler-evapo- 










ration 


$9,450 








Fuel oil 3i cts. per gal. i ton to 4 gal. . . 




$3,020 






Fuel oil 3i cts. per gal., i ton to 4$ gal.. . 






$3,400 




Pea coal, anthracite, $4.50 per ton, 26 










tons ice per ton 








$3,740 


Supplies: oil ammonia, waste, 6 cts. per 










ton with steam, 7 cts. per ton with oil 










and gas 


1,300 


1,500 


I.SOO 


1,500 


Labor 365 days 


10,600 


10,800 


IO,8OO 


12,250 


Repairs, 3% 


3,060 


3,000 


3,170 


3,470 


Depreciation: 
Buildings 3% 


I, IIO 


870 


930 


1,050 


Equipment 5% 


2,770 


3,120 


3,320 


3.370 




$28,290 


$22,310 


$23,120 


$25,380 


Assuming 33% full capacity, 33% i capac- 
ity, 33% } capacity gives 21,600 tons at 


$1.31 


$1.03 


$1.07 


$1.17 



DAILY LABOR COST 



Engineer chief .... 
Engineer assistant . 
Oilers, 2 shifts. . . . 
Firemen, 2 shifts. . 

Tankmen 

Storehouse men . . . 

Total . . . 





$5.00 


$6.00 


$6.00 


$6.00 




3.50 


3.50 


3.50 


3.50 




4.00 


4.00 


4.00 


4.00 




4 -SO 






4.00 




8.00 


12.00 


I2.OO 


12 .OO 




4.00 


4.00 


4.00 


4.OO 




$29.00 


$29.50 


$29.50 


$33.50 



378 



ELEMENTS OF KEFRIGERATION 



COST or ICE PLANTS FOR STEAM AND OIL ENGINE OPERATION 

L. K. Doelling, A. S. R. E. Journal, Sept., 1915. 
INVESTMENT COSTS 





STEAM ENGINE PLANT. OIL ENGINE PLANT. 


Apparatus. 










200 tons. 


; ~ df un 












datum 16 ' r P 












Piping for oil, water exhaust and 












oil tank 








1,500 


2,500 


4,500 


Boiler plant and foundation. . . . 


$3,ooo 


$5,5oo 


$10,000 








Piping for steam, exhaust and 














water 


1,500 


2,000 


3,000 








Steam engine and foundation 














direct connected:". 


5,000 


9,500 


15,500 








Compressor, condenser and am- 














monia piping 


5,500 


10,000 


18,000 


5,500 


10,000 


18,000 


Freezing system 


14,000 


27,000 


50,000 


14,000 


27,000 


50,000 


Ice Storage 
Buildings 
Land 


1,000 
16,000 
S.ooo 


1,500 

35,ooo 
8,000 


2,500 
60,000 


1,000 
16,000 


1,500 
35,ooo 


2,500 
60,000 


Total 


$51,000 


$98,500 


$171,000 


$57,500 


$109,500 


$192,000 



OPERATING COSTS 



Labor, fuel and ammonia for 














for 216 days full capacity. . . . 
Labor for remainder of year . . . 


$10,314 
2,736 


$16,740 
4-174 


$29,268 
5,832 


$6,454 
2,348 


$10,908 
3,672 


$18,360 
5,328 


5% depreciation on equipment. 


1,500 


2,775 


4,950 


1,825 


3.325 


6,000 


3% depreciation on building. . . 


480 


1,050 


1, 800 


480 


1,050 


1,800 


5% on total investment for taxes, 














repairs, water and incidentals 














(no allowance for interest on 














investment) 


2,550 


4,925 


8,550 


2,875 


5,475 


9,600 


Total 


$17,580 


$29,664 $50,400 


$13,982 


$24,430 


$41,088 


Tons per year 


10,800 


21,600 


43.000 


10,800 


21,600 


43,OOO 


Cost per ton 


$1.62 


$1.40 


$1.17 


$i .30 


$1.11 


$o 96 


(Cost with interest) 


(1.86) 


(1.63) 


(1.36) 


(I- 57) 


(1.35) 


(I. 13) 



DAILY OPERATING EXPENSE 



Labor 
Fuel (coal $3.50, oil at 3.5 cts). 
Ammonia, oil, waste 

Total 


$19.00 
22.75 
6.00 


$29.00 
38.50 

IO.OO 


$40.50 

77.00 
18.00 


$16.00 

7.88 
6.00 


$25.50 
15 .00 

IO.OO 


$37.00 
3O.OO 
18.00 


$47-75 


$77.50 


$135.50 


$29.88 


$30.50 


$85.00 



H. Swan shows that although a compound-engine plant 
would cost 12% more than the steam-engine plant above the 
fuel cost would be so much reduced that the cost of ice would 
be reduced by 10%. 

L. C. Nordmeyer gives the following costs for a loo-ton 
plant at 57% load factor. 



COSTS OF INSTALLATION AND OPERATION TESTS 379 



COST OF PLANT 





Simple Steam 
Engine. 


Compound Con- 
densing Steam 
Engine. 


Diesel Oil 
Engine. 










Machinery 






8^ 923 












$125,000 


$136,400 


$143,923 



OPERATING COSTS PER TON PRODUCED 



] 

Cost of water per ton . . ' 




$0.09 


Cost of fuel per ton. ... $o . 976 


$0.753 


o. 226 


At 25 cts. per 42 gals. . . (1.03 bbl. per ton) 


(0.79 bbl. per ton) 


(0.238 bbl. per ton) 


Fixed charges per ton 






on machinery [ o . 546 


0.642 


0.821 


Operating cost per ton . 


0.579 


0.579 


0.516 


Total cost per ton . 


$2. IOI 


$1.974 


$1.653 


Fixed charges per ton 






for building o . 504 


0.504 


0.504 


Total 


$2.605 


$2.478 


$2. 157 




Equipment: Two 


6o-ton refrigera- 


Equipment: Two 6c-ton 




ting machines an 


d engines. 


compressors belted to 




Water tube boiler 


ind feed pumps. 


two 225 H.P. Diesel 




Feed water heater, 


:himney. 


engines. 




Freezing system. 




Two 40 K.W. generators. 




Steam condensers. 




Raw water freezing system. 




Ammonia condense 


rs. 


Cooling tower. 




Air lift pumps, air 


compressors. 


Two circulating pumps. 




Circulating water i 


jump. 


Two brine pumps. 




Cooling tower. 




Cold storage piping. 




Brine pump and cooler. 
Piping for storage. 


Piping and covering. 
Ammonia, calcium chloride. 




Piping for apparatus and covering. Two-oil tanks. 
60 K.W. generator and engine. Foundations. 




Ammonia, calcium 


chloride. Ammonia condenser. 




Foundations. 







In the above tables allowance has not always been made 
for interest on the total investment. The items should be care- 
fully gone over and the following percentages allowed: 

Interest on total cost (return on investment) 5 to 8% 

Taxes i to 2 

Insurance (\% fire proof, i% frame) \ to i 

Depreciation on machinery (about 14 years life at 



Depreciation on buildings (25 years life at 5%) .... 

Repairs to machinery 3 

Repairs to building i 



2 

to 
to 



4 



Total 



i6 to 



380 ELEMENTS OF REFRIGERATION 

Ice Delivery Data: 

Cost of wagons $275 .00 

Cost of horses 300.00 

Cost of harness 35 

Cost of feed 50 per day 

Cost of drivers 2.75 

Cost of helpers 2 .00 " 

Mr. G. T. Lawrence gives the following in Ice and Re- 
frigeration, Apr., 1913. 

Cost of i team i horse per month. 

Feed, shoeing, driver, hostler, repairs $81.12 

Insurance i . 68 

Depreciation, 8|% on $720 5 . oo 

Interest, 5% on $720 3 . oo 

$90.80 
Cost of 3 -ton truck per month: 

Driver, repairs, oil, gasoline and tires $138.00 

Insurance 10 . oo 

Depreciation, i6|% on $3600 per month 50.00 

Interest, 5% on $3600 per month *5 oo 

$213.00 

One truck can do the work of 2.93 teams costing $266.04 
per month. 

Amount retail delivered per day per man i\ tons 

In Ice and Refrigeration for Dec., 1914, the following data 
are given for 5-ton truck: 

Cost per day ' $18.45 

Cost per mile o . 39 

Cost per hour 3 80 

Cost computed on equal time standing and running. 



COSTS OF INSTALLATION AND OPERATION TESTS 381 

REFRIGERATED RAILROAD CAR DATA 

Cost of refrigerator car $1600 

Cost of box car 1 100 

Weight of refrigerator car 46,800 Ibs. 

Capacity 15,000 to 35,000 Ibs. 

Length: Over couplers 44' 3^" 

Over sheathing 40' 1 i|" 

Inside 39' lof " 

Inside between ice tanks 33' 2 \" 

Width: Over sheathing 9' 2f " 

Inside 8' 2}" 

Gauge track 4' 8" 

Height: Rail to top of brake shaft 13' 5!$" 

Rail to running board 13' \" 

Rail to eaves 12' $W' 

Rail to coupler 2' io|" 

Inside 7' 5T 3 e" 

Cubic capacity: Total 2444 cu.ft. 

Available 2032 cu.ft. 

Ice capacity at each end 11,000 Ibs. 

Insulation, roof: \" 3-ply flax felt 
f " ship lap, 2 ply 
f " ceiling 

Sides: H" siding, f" furring, 2 ply 
f " shiplap 
I", 2 ply, flax felt 
f|" lining 

Floor: J" flax felt, 3 ply 
if " ship lap floor 
I" ship lap, 3 ply 
Average amount of ice put in at each station . 5345 Ibs. per car 

Cost of icing, Chicago to New York $16.00 

Cost of icing, California to Chicago 62 . 50 

Cost of ice and salt per ton at Indianapolis . . 2 . 85 

Cost of cleaning cars 31 to 80 cents 

Cost of stripping cars $2 . 20 



382 ELEMENTS OF REFRIGERATION 

Rates of Precooling by Mr. A. Faget: 

Asparagus cars 25 per hour air heated in passage from 16 

to 38. 

Celery cars, 16 per hour air heated in passage from 14 to 40 
Grape cars, 14 " 14 to 31 

Orange cars, 8 10 to 30 

Air employed, 8000 cu.ft. per car per minute. 

Charge for preceding $25 .00 per car 

Charge for precooling and first ice . 55 . oo 

Charge for icing to Chicago 62 . 50 

Charge for icing to New York 75 .00 

Cost of precooling and icing 32 . 50 

Charge for use of car 7 . 50 

ICE i OR PASSENGER CARS 
20 Ibs. of ice per car per 300 miles. 

RINK DATA 

Use il-in. brine pipe, 4-in. centers; using about 2 to 3 
lin.ft. of pipe per square foot of surface. This may be formed 
in metal pan placed on 3-in. cork boards and fed from a brine 
main. 

ICE CREAM DATA 

(W. W. Wren, Ice and Refrigeration, May, 1915): 

Cost per gallon: Milk and cream 28 .4 cts. 

Sugar 3.9 

Ic e 5-9 

Salt 2.0 

Fruit i.i 

41.3 cts. 

Over-run or swell 68^% 

Shrinkage 6.1% 

42 to 45 Ibs. of ice per gallon of ice cream. 
Temperature for hardening (6 to 8 hrs.) o F. 



COSTS OF INSTALLATION AND OPERATION TESTS 383 



Temperature for ice making 15 

Temperature for ripening (12 hrs.) . . 33 

Mixing tank to be refrigerated with brine-freezing machine 

15 minutes to batch. 
Power: i H.P. for 5-gallon freezer, single. 

i H.P. for 50 gallons per hour in gangs from 
i motor. 

Mr. J. H. Stone in the Transactions A. S. R. E. for 1910, 
gives the following data for warehouses using insulation of 
various values when the temperature of storage is 30 and the 
average outside temperature for eight months is 70. 



B.t.u. 

per Sq. 
ft. per 
24 hrs. 
per 
Degree. 


Cost 
of In- 
sula- 
tion 
per 
Sq. ft. 


Cost 
of In- 
sula- 
ting 

IOOOO 
Sq. ft. 


Tons 
of Re- 
friger- 
ation. 


Total 
Tons 

S P e e a r - 
son. 


In- 
crease 
Cost of 
Insula- 
tion. 


De- 
crease 
Cost of 
Mach- 
chin- 
ery at 
$450 

Ton 


g 4* 


De- 
crease 
in 
Opera- 
tion at 
Ji.oo 

Ton. 


Net 
De- 
crease 
in Cost, 
Dol- 
lars. 




1 8 cts. $1800 


5-6 


1333 












3 


22 2200 


4.2 


IOOO 


$400 


$630 


$230 -$34.50 


$333 


$367.50 


2 


27 2700 


2.8 


667 


500 


630 


130 19.50 


333 


352.50 


i. 5 


36 


3600 


2.1 


500 


900 


315 


585 87.75 


167 


79.25 


I 


50 


5OOO 


1-4 


332 


1400 


3i5 


-1085 212.75 


168 


-44-75 



Note: The last three columns are changed from those 
given by Stone. This table gives decreased cost of any condi- 
tion on one line over that of the preceding line. If money 
invested is the important item the 2 B.t.u. condition is the best; 
if operation, then 1.5 B.t.u. is the best condition. In this 
analysis the value of space taken by insulation is not considered. 

STUDY FOR MINNEAPOLIS FOR COST OF NATURAL ICE AND MANUFACTURED ICE 
FOR 100,000 TONS 

Ice and Refrigeration, March, 1915 

INVESTMENT 

Natural ice, storehouse for 100,000 tons $125,000 

Manufactured ice Plant (275 tons) 400,000 



Storage 60,000 tons . 
Land. . . 



60,000 

20,000 



$480,000 



384 



ELEMENTS OF REFRIGERATION 



COST OF PRODUCTION PER TON 



NATURAL ICE 
Delivery to storage $ 
Loss 
Delivery to platform 
6% interest on $1.25 per ton 
10% depreciation on $1.25 per ton 
2% taxes 


5.30 
.04 
.15 
.075 
.125 
.025 
.035 
.042 

.792 
.400 
.132 
.25 


MANUFACTURED ICE 
Manufacturing cost $ 


.00 

.288 
.049 
.192 
.096 
.160 


i % insurance on $4.80 










3i % sinking fund 

$ 




.785 
'.642 
.442 


Overhead charges 10% 


10% shrinkage in cars 


C 11' * ~ { 


t.869 




Cars to wagon 


$ 


.574 
750 
432 


Overhead charges 10% 



Selling price $4 756 



DATA FROM STUDY OF HOUSEHOLD REFRIGERATORS IN ROCHESTER, N. Y. 

By John R. Williams 



Weekly Amounts 


Ice. 


Cost of Ice per 


Year. 


Temperature 


L 


50 Ibs. or less 
51 to 75 Ibs 


7% 
12% 


Under $5 
$5 to $10 


.- 23% 
.. 43% 


In refrigerators: 
Below 45 


..I 4 % 


76 to 100 Ibs 
101 to 200 Ibs. . . . 
201 to 300 Ibs. . . . 
301 and over 


18% 
47% 
.10% 
6% 

100% 


$10 to $15 

$15 tO $20 

$20 and over. . . . 


-. 15% 
.- 7% 

.. 12% 
100% 


45 to 50 
50 to 60 
Over 60 
Living Rooms: 
Below 60 
60 to 70 


27% 
.-51% 

.. 8% 

-. % 
42% 










Above 70 
Cellars: 
Below 55 
Below 60 . . 


.-58% 

o% 
8% 










Above 60 


.-92% 



COSTS OF INSTALLATION AND OPERATION TESTS 385 



PROPERTIES OF SATURATED AMMONIA, NH 3 

With Permission of G. A. Goodenough 





I 


03 


Ca 


Is 





..d 




1 




'o 
= 


1 3 


. 




o> 


n 


~g -*-> 


8.3 




j *? 


O h 




> 




3 3 


3^-* 


"3 


aj 


3 


i-l 


g W . 


Oj ^ 


s 


JP 




*o . 


o . 







5 


" 


3 


Tempera 
Deg. F 


Pressure, 
Sq.in. 


U'S'-' 

J* 


H 


ji 


jit 


External 
B.t.u. 


i 

1H 
w 


Entropy 
ization 


Entropy 
Vapor. 


P 


3 


! 


Tempera 


t 


p 


' 


r 


" 


p 


* 


s' 


r/T 


5" 


t>' 


v" 


m 


i 


-25 


15.6 


-59-8 


591- 1 


531-3 


542.1 


49.0 


0.129 


1.360 


.231 


0.024 


6.95 


0.059 


-25 


20 


17.9 


-54-6 


587-4 


532.8 


538.0 


49-4 


o. 117 


1-336 


.219 


0.024 


4.89 


0.067 


20 


-IS 


20.5 


-49-4 


583.6 


534-3 


533-9 


49-7 


0.105 


1-317 


.207 


0.024 


3- IS 


0.076 


-IS 


10 


23.3 


44-2 


579-9 


535-7 


529.8 


SO. i 


0.094 


i . 290 


.196 


0.024 


1.63 


0.086 


IO 


5 


26.5 


-38.9 


576.1 


537-1 


525-6 


50.5 


-0.082 


1.267 


1.185 


0.024 


0.32 


0.097 


-5 





29.9 

33- 8 


-33.7 


572.2 


538.5 


521.4 


50.8 


0.071 


1.245 


1. 174 


0.024 


9.19 

8 20 


0.109 


o 


5 

10 


38.0 


-23.2 


564-4 


541.2 


512.9 


Si-5 


0.048 


i . 202 


1. 153 


0.025 


7-34 


0^136 


S 

IO 


15 


42.7 


-17.9 


560.4 


542-5 


508.6 


51-8 


0.037 


1.181 


1. 143 


0.025 


6.58 


0.152 


IS 


20 


47-7 


12.6 


556.3 


543-7 


504.2 


52.1 


O.O2O 


1.160 


1. 134 


0.025 


5-92 


0.169 
o 187 


20 


25 
30 
35 


53 . 3 

59-4 
65-9 


1.9 
3.5 


548-1 
543 . 9 


546.2 
547-4 


495.4 
491.0 


S2.7 
52.9 


O.OO4 
O.OO6 


I . IO 


1. 115 
1.106 


0.025 

0.025 


4.82 
4-36 


0^208 

o. 229 


25 
30 
35 


40 


73-0 


8.9 


539-7 


548.5 


48'6.5 


53-2 


O.OI7 


1.08 


1.097 


0.025 


3-96 


0.253 


40 


45 


80.8 


14-3 


S35-3 


549-7 


481.9 


53-4 


0.028 


i. 06 


i .089 


O.O26 


3 .60 


0.278 


45 


50 


89.1 


19-8 


531.0 


550.8 


477-3 


53-7 


0.039 


1.04 


1.081 


O.O26 


3.28 


0.305 


SO 


55 
60 


98.0 
107.7 


30 '.9 


522.0 


552.9 


468.0 


54-0 


O.O6O 


1.005 


1.065 


0.026 


2 . 99 
2.73 


o . 334 
0.366 


55 

60 


6s 


118.1 


36.5 


517-5 


554-0 


463.3 


54-2 


O.O7I 


0.986 


1.057 


O.O26 


2.50 


0.400 


65 


70 


129.2 


42.1 


512.8 


SSS-O 


458.5 


54-3 


O.oSl 


0.968 


1.050 


0.026 


2.30 


0.435 


70 


75 


141.1 


47.8 


508.1 


S56.0 


453-7 


54-4 


O.O92 


0-950 


1.042 


0.027 


2 . II 


0.474 


7S 


80 


153.9 


53.6 


503.4 


557.0 


448-8 


54-6 


0.102 


0.933 


1.035 


O.O27 


1.94 


0.516 


80 


85 


167.4 


59-4 


498.5 


557-9 


443-9 


54-6 


O. 113 


0.915 


i .028 


O.O27 


1-79 


0.559 


85 


90 


181.8 


6S.3 


493-5 


558.9 


438.9 


54-6 


O. 12^ 


0.898 


1.022 


O.O27 


1.65 


0.606 


90 


95 


197-3 


71-3 


488.5 


559-8 


433-9 


54-6 


0.134 


.881 


I .015 


O.O27 


1-52 


0.656 


95 


IOO 

105 


213.8 
231.2 


77 . 2 
83.4 


483.4 
478.2 


560. 7 
561.6 


428. ; 
423.5 


54-7 
54-7 


o. 145 
0.156 


. 86*; 
0.847 


I . OO9 
I .OO3 


O.O28 


1.30 


0.766 


05 


US 


269.2 


95-9 


467.4 


563.3 


412.9 


54-S 


0.177 


0.814 


0.991 


O.O2? 


I. 12 


0.891 


IS 


I2O 


289.9 


IO2 . 2 

108 7 


461 .9 


564.2 


407.5 


54-4 


0.188 


0.797 


0.985 


O.O28 


I .O; 


0.960 


20 


125 


311.6 




456.3 


















i . 031 


125 



386 



ELEMENTS OF REFRIGERATION 

ogpadg 

;B3H I """ " )>n ^' n ' n ">">">w ooooo oooo 

MCO *3- 10 10 r~ oo oo 10 w t^ o roio^r^N 00 *too O 

:31UOQ ! '. loa-toWat^-iorJod 4 o' t^- 4 w ovt^4o 

-j^grj * 1- 10 100 O t~oo OvO> 0"MNir> ro-* 100 

ogpadg .. .oioioioTj-TtforororooiNNNwwM 

*1010 O t^ 1^00 Si ".0 M" (N JOTT^- 

oyp'adg 

ogpadg I ! : 4 44r^ 

' ' ' ' ' S'SwK 

og'pa'dg 

00 O O M 1000 MOO O 10 M 10 

O 00 <N N ^ ^t o roo 
10000 O> O " ro-*iO 

00 O N 
M"?M 

jad -sqq 'aanssajj M MMro^n Ttrj-ioioo o t-oo oo M N -s-ior- a M ro 



COSTS OF INSTALLATION AND OPERATION TESTS 387 



PROPERTIES OF SUPERHEATED AMMONIA Continued 

Arranged from Goodenough Tables 


ENTROPY 


Jf 


oypadg 


00^0=0 ""-00.0 OMO^ -N^roo ^^"0^ .orOMU, 


WU SH 


<so " "^!^ M "? r ? t 7 oot 7 *!"?""'? '!"? '71: 


POrOTtLOi^OOt^r^QO OvOOOM !NPO^f^tty-)\Ol^r~OOC> O " N M 
ID IO in iO 1C T> ID 1C IO lO 10 nO O O ^"OOxOO sO O O <5 O i- t^ t^- <^ 




NOOM^V, oo^ro^ 00,^-000 oooor, ^ ao c. r,oc 






* 


oypadg 


1^4^ ooa Voo ^":n^*" ^^ 


W & H 


isiid sis^jiss'Siis? ?^^^>s?^ & is 

1010 ID IDIOIDIOID IDtDlDvOO sOOvOOvO O O >O O O O l> I- t- 


WdX 


r^ 


; M J?'8S5SS:SS25faSU8|g5a| 


I 


oypadg 


:;^::-ooL^^;nn^^r^::.' 


,,UOO H 


; j'SSt SS1& JSISi HIE 




' 'roOoOOoOTft-0Niot-t-r-0OMONOtr->00 








oypadg 


-00 OOINOOOOOOlOOOr<30vM ^too 00 MOOwOOOOOONt^ 


. . . . . "T "? *? ^ . ". . *? N . . "1" ? "? .. *T "? " . *\ "? " . . oc .- 


. . .MM M 2 a OX -*^"5 ^^ 


iua;uoo ^ 




: : :KSSK^^K^Sa5o5So 5 o h ^SSS^R 


-^- x 


. . . 


. . .2 ^iNN^ioRooao"" 1 ^ -to oo ov o N" nv> <~~ S o N n 


... 1 





oypadg 


... .0, MWf-oOM no-'7 "~^o7 *".*:"? '?". aoc . 


. . . .M MS "" 00 t ~ t ~ 00 tttro roro 


^H 


: : : : M . tl*".^ " f ?. 00< ! "? r . M . ". T". f?"? " T?. 


. . . .5 S^^S-S KK^g S5552 5^^ ^S^5 


aan^aduiax 




Oi 


oypadg 


: : : : : :^2? ^J5J^|^ ^f^llf ^ 


! '. '. i '. ' ^-ao^ t^oorfo ^o,^aa cr^^-^o CXMMO 


.^u^ 




SWmiadUX I;;;;;; MMMMMMM NNNNNN ^ 


oo 


oypadg 






SH 


: : : : : : : M~^a^a^o o^oo ^S^ o-H : 


..... . .10^,0 ......10000 OOOOO 0000 


Mmtuaduiax 


Qj^jjj -*""o o S S jr285SSS8 


-jadiuaj, uoi^aruBg 


-gsrrss rfoTo Sg^I^Us^ al?s 


aad -sqq 'ainssajj 


^7?SS SSS% ^SISS o^a^ ^^5-K^ ,2SS 


M N <S M 



388 ELEMENTS OF REFRIGERATION 

PROPERTIES OF SATURATED CARBON DIOXIDE, CQ 

Based on Curves of the Institution of Mechanical Engineers of Great Britain and Work 
of M oilier 





I 


3 


** 


8 




*4 




1 


I 


S 

PC 


"o 


*;* 






B 


S 


Is 


S 1 ^ 


jfl 


!? 


^ 
S 




> 
*O . 


> 
8 


p 


Ic3 


fe 


jj 


afc 

I* 


Pressure, 
Sq.in. 


P 


* 


31 


jit 


External 
B.t.u. ] 


fcS 

&& 
fa 

M 


Entropy 
ization 


Entropy 


ilS 

F 


* 0,7] 


* 


Tempera 


/ 


p' 


," 


r 


*" 


p 


* 


s' 


r/T 


s" 


r" 


v" 


m 


t 


25 


202 


22.2 


124.7 


102. S IO8. I 


16.6 


-0.050 


0.287 


0.237 


0.05 


0.459 


2.17 


-25 


20 

-IS 


218 
238 


20.5 
- 8.8 


123.2 
121 .6 


IO2.?'lO7. I 


16.1 


0.046 


0.280 


0.234 


0.06 


0.416 

0.381 


2.42 
2.62 


20 

IS 


IO 

-s 


260 
283 


5.3 


118.3 


103.0 


102.4 


15-9 


0.034 


0.260 


0.226 


o.o 6 


0.320 


2.87 
3.12 


IO 

-s 





308 


- 3-5 


116.5 


103.0 


100.7 


IS. 8 


-0.030 


0.254 


0.224 


o.o 6 


0.293 


3.41 


o 


S 

10 


334 
362 


1.6 

-9-7 


114.7 


103.1 


99.1 


15.6 


0.027 


0.248 


O. 221 


o.o 6 


0.268 


3-73 
4.08 


s 

IO 


is 

20 

25 


391 
422 

454 


-5.6 
3- 


108.3 

105.8 


102.7 


93-6 


14.7 


-0.013 








0.205 


4.88 
5-32 


IS 

20 

25 


30 
35 


489 
526 


I. 

I. 


99.7 


IOI.2 


86.1 


13.6 


+ O.OO2 


0.200 


O.2O2 


o.o 8 


0.157 


S.8I 
6.37 


30 
35 


45 
50 


606 
650 


7. 

10. 


92.0 
87.4 


99.4 

98.2 


79-2 
75-2 


12.8 


0.012 


O.lSl 


0.193 


o.o 8 


0.132 


7-58 
8.33 


45 
So 


00 


696 

744 


14. 

17- 


77-4 


95-3 


66.5 


10.9 


O.O3O 


0.149 


0.179 


o.o o 


0.099 


9-17 

IO. IO 


00 


70 


848 


26: 


64.7 


91.1 


55-4 


9-3 


0.045 


0.123 


0.168 


0.0 I 


0.080 


12.50 


70 


11 

85 


962 

IO22 


37. 
45- 


47-5 

33.8 


84-7 

79.2 


40.7 
28.5 


6.8 
S-3 


O.O6S 
0.080 


O.O89 

0.061 


0.154 
0.141 


o.o 4 
o.o 6 


0.062 
0.054 


16.13 
18.52 


85 


88.4 


1070 


63. 


0.0 


63.0 


o.o 


O.O 


O. 112 


o.ooo 


O.II2 


0.035 


0.035 


28.57 


88.4 



COSTS OF INSTALLATION AND OPERATION TESTS 389 







j.u 


t^OfO OlOOvoO'O sOiO^r^N MM OO* 






o.^* i 


M . . . 






CO 


00 00 







111 

















f* 


2JS ^"J5 2*22" "5 H- 














1-3" 


: : : :5^S SSSSS S^ SS 






a > 3 


- . 






CO 














", 


ri C " 









ao! 


-00^00 " 2 H w 2" !?r wS 






















g 


: : : :vdu; o'o r:d 4o 

















. . ... 








$8 SS^^o' o oooo" 






<u> | 


. . . 






CO 




t 


s 

o 


I,M 


'oo ooo'oo o " MM 


g 








i 




i 


!ii m ^ u u 






"5-1 w 


' o 'too ^f O> 1OO O t^ 
MOOO> 0,00 OOt- 

MMMMQ 00 OO 






co 






Ov 


gg| 


i i i i j i T ^ ^ 




O 


*" 








fl 


: : : : : : . . tff t . t 00 . 






lii 


: : : : : : :&,? Sg. 

"000000 






CO* 










. . . . . . 







II! 


I! 1 in ;s*s ^ ss 














i 


III III ^ *' ^ 




2c 




"?~.~. : : 




1* 


y 


Tin 11 : : 




g! 


c 

'I 
1 


UHi IIHS Hill HUI l!|il 



390 



ELEMENTS OF REFRIGERATION 



p 

If 



Set 

!& 



3 E 

4J> "S 

dfe 

E ai t~ r-5 100 10 ^ ro M t- ro rhO looo aoc ) O _M o g a O 

" oo -d- o-oiooooo mooroo-* ro o M m 10 oo o 

<C C .2^?.^^ %HOOOt- -O'tMMOl OOt-OlO't Sl MI 

il 

Kg 
O 

^ M | M M 1 IN f*3^-Oi/)sO t^OO* O> ^ 

Q 

S ' * ' 'S-'S o *O ^-^ ^M ^ O O M 1O O O POO 

> 
I : : : ?2 22? - sass'g s^ ss 

u 

' O 11 O 

HQ 



COSTS OF INSTALLATION AND OPERATION TESTS 391 



PROPERTIES OF SULPHUR DIOXIDE, SOz 

Based on Curves of the Institution of Mechanical Engineers of Great Britain and Work 
of Lange 





& 

3 


"3 . 

" jj 


1; 


"o 

*J J2 


1 _ 


tt 




c 




"o a 


; 3 

3U 


"o u 

I s - 


. 


3fe 

2 
& 


,J 
2 . 

3 C 


! m 

o|3 




c a3 
^ 3 


1*3 





"o 

11 


li 

li 


s 

ig 


*-g 


o u . 

i|s 


^5 

g^ 


3fe 

li 


ia 
H 


!" 


rf.S'S 
X Jft 


||3 


JM 


JS& 


i 




l> 


3>* 


P3 


$**> 


^ 


Ja 


















0.380 




' 


v" 

13.89 


m 


t 


25 


S-i 


17.4 


165.5 


148. i 


135.0 


13. i 


0.038 


0.342 


O.OI 


0.072 


25 


20 


5.9 


15.9 


164.9 


149.0 


[35.9 


u.i 


-0.035 


0.375 


0.340 


O.OI 


12 .02 


0.083 


20 


15 


6.8 


-14.4 


164.2 


149.8 


136.6 


13.2 


0.031 


0.369 


0.338 


O.OI 


10.42 


0.096 


15 


10 


7-9 


12.9 


163.6 


150.7 


137.4 


13.3 


0.028 


0.364 


0.336 


O.OI 


9. 12 


O. IIO 


IO 


5 


9-1 


-II. 4 


162.8 




138.1 


13.3 


-0.025 


0-358 


0.333 


O.OI 


8.05 


0.124 


-5 


o 


10.4 


9-9 


162.0 


152.1 


138.7 


13.4 


O.O2I 


0-352 


0.331 


O.OI 


7.12 


0.140 


o 


5 


11. 8 


=1:1 


161.3 


153.0 


139.5 


13.5 


-0.018 


0.347 


0.329 


O.OI 


6.27 


0.159 


5 


15 


15-0 


-5.3 


159.7 


154.4 


140.7 


13.7 


O.OII 


3-336 


0.325 


O.OI 


4.95 


O. 2O2 


15 


25 


19.2 


-2.2 


158.3 


156.1 


142.1 


14.0 


0.005 


0.326 


0.321 


O.OI 


3.96 


0.253 


25 


30 


21.5 


-0.6 


157.4 


156.8 


142.5 


14. i 


O.OOI 


0.321 


0.320 


O.OI 


3.56 


0.281 


30 


35 

40 

45 


24.0 
26.7 
29.8 


1 .0 

2.6 

4-3 


156.3 
155.4 

154-3 


157.3 
158 .0 
158.6 


143.1 
143.7 
144.2 


14.2 
14.3 
14.4 


0.002 
O.OO5 
O.O08 


O.3i6|o.3i8 
0.311 0.316 
0.306 0.314 


O.OI 
O.OI 
O.OI 


3.20 

2.88 
2.61 


0.312 
0.347 

0.383 


35 

40 

45 


50 


33.0 


6.0 


153.3 


159.3 


144.8 


14-5 


O.OI2 


0.301 


0.313 


O.OI 


2.36 


0.424 


50 


55 


36. S 


7-7 


152.1 


159.8 


145.3 


14-5 


O.OI5 


o. 296 


0.311 


O.OI 


2.15 


o. 4 6S 


55 


60 


40-4 


9.3 


151-1 


160.4 


145.8 


14.6 


0.018 


0.291 


0.309 


O.OI 


1.96 


0.510 


60 


65 


44-7 


1 1 .0 


149.9 


160.9 


146.2 


14.7 


O.O2I 


0.286 


0.307 


O.OI 


1.7* 


O.S62 


65 


70 


49.2 


12.7 


148.8 


161.5 


146.8 




0.025 


0.281 


0.306 


O.OI 


1.62 


0.617 


70 


75 
80 


54-0 
59-3 


14.4 


147-6 


162.0 


147.2 


14.8 


O.O28 


0.276 


0.30^ 


O.OI 


1.48 


0.676 


75 
80 


85 
90 


70.9 


19.5 


143-9 


163.4 


148.5 


14-9 


0.037 


0.262 


0.299 


O.OI 




0.870 


85 
90 


95 


77-5 


21.3 


142.5 


163.8 


148.8 


15.0 


0.041 


0.257 


o. 298 


O.OI 


1.05 


0.952 


95 


IOO 


84.4 


23. 1 


140.9 


164.0 


149.0 


15-0 


0.044 


o. 252 


o. 296 


O.OI 


0.96 


1.042 


IOO 


105 
no 


91.8 
99-4 


24.8 
26.6 


139.4 
137.7 


164.2 
164.4 


149.3 
149.5 


14.9 
14-9 


0.047 
0.050 


o. 247 
o. 242 


O . 29- 

o. 292 


O.OI 
O.OI 


0.88 

0.82 


1.136 

I . 22O 


105 

IIO 


iiS 










14. 9| -.-aap-o, 




O.OI| ~.,, 


1.299 





392 



ELEMENTS OF REFRIGERATION 



oypadg 

<t ro O >O n t^Nt^roO o u? O\ r*5 > fOOv^t-w 

in^aaduiax I | 5 M S Nroro^^- v> min-o^o t-t--ooo> 
IA 3P 3d S 

[t 

oypadg 

| 

3 HP 3d S 

"" "5 V) \r> 10 

ajtHBaaduiaj, uoiiBjn^'Bg "* 

urbg J9d -sqq aanssaj<j 



COSTS OF INSTALLATION AND OPERATION TESTS 393 



I 



o 


""1A=.9PS 


-" *-^ " 


W 


,. W o 3 , H 


ii^ mil i 




2^?^^ ^^^^.S 1 fi 


l-i l-l 


% 

~ 


aiunpA oypadg 


5^332 'oS52S t^-"" 




.,ua;uo 3 ^ H 


S5^s 5IHI I^lil i 


M M W M M H M 


'^ x 


o^-^S ^g^^ ,? S5^^ 




6 


-au^oAoypadg 


St*r" ^^- t 5 ." 12 . 2 . ? S ^ 




0-H 


t^t^tCt-t^ "'S-ooMoo oo"Sooooa aSSa 




w-ta,i 


sss? ssEssi ^^^55 jis^a 




n 


*9uin|o^Y oyioadg 


^t ro M HI o OXt-OiO TfrooiMO OO\O*oo 


(NNNMW MOOO 






z 
W 


o 




M MM 


w d-^ 






o 


a^pAoypadg 






,u^oo^ H 


555SS SSSS ^^ S855 




W^do^i 


^5^5^ g^SaS; ^g^S^S SSSS 




o 


.au^OAo^S 


Ov oooot-sO^f roojHii-to OO\O\oO 


.... oooo 


WOO ^H 


'' :: 6 *' ^4i ^ ao^ ^44 


.... H M 


.^^du^i 


: : : :S ^S^S^ a 8;^ : : S^^^ 




o 


-au.npAoyp^g 


'.'.'.'.'. '.'.'.'.'. '. '. M M M d d d d 




'...'.. ..ro^t*o or-r-oo 





i i : : : : : : : : : :& 2B2 


ajn^BJaduiaj, uoi^-BamBg 


^^inioS vOvo'o'vO 1 ^ oooo > SSl 0000 


ui -bg jad 'sqq 'aanssaaj 


SSS3S- ^5^g.K 5^&SS i?as 



394 ELEMENTS OF REFRIGERATION 

TABLE OF CHLORIDE or CALCIUM (CaCU) SOLUTION 



Specific 
Gravity 
at 60 F. 


Degrees 
Beaume 
at 60 F. 


Degrees 
Salom- 
eter at 
60 F. 


Lbs. 
(CaCU) 
per gal- 
lon So- 
lution. 


Lbs. 
(CaCU) 
per Cu. 
ft. Solu- 
tion. 


Percent- 

(CaX-U) 
by 
Weight. 


Freezing- 
point F. 


Specific 
Heat at 
32 F. 


Weight 
per 
Gallon 
at 60 F. 


.021 


3 


12 


1 


3f 


3 


+ 2 9 


0.965 


8. 54 


-043 


6 


27 


I 


7i 


5 


+ 27 


0.920 


8.70 


.066 


9 


36 


I* 


8| 


7 


+ 25 


0.883 


8.88 


.074 


10 


40 


ii 


ni 


9 


+ 23 


0.868 


8.96 


.082 


ii 


44 


ii 


13 


10 


+ 21 


0.857 


9-05 


.099 


13 


52 


2 


IS 


12 


+ 18 


0.830 


9.19 


US 


IS 


62 


2i 


I 7 


14 


+ 14 


0.808 


9.29 


.160 


20 


80 


2* 


19 


18 


+4 


0-753 


9-65 


.179 


22 


88 


3 


22j 


20 


-i-S 


0.732 


9-83 


.198 


24 


95 


3^ 


26 


22 


-8 


0.714 


10.00 


.219 


26 


104 


4 


30 


24 


-17 


0.695 


10. 16 


239 


28 


112 


4* 


34 


26 


-27 


0.678 


10.32 


.261 


3 


120 


5 


37i 


28 


-39 


0.661 


10.50 


-283 


32 


128 


5^ 


41* 


30 


54 


0.643 


10. 72 



If more chloride is used the freezing-point is raised. 
CU for each ton of ice-making capacity. 



Use about i ton of 



TABLE OF SODIUM CHLORIDE (SALT) SOLUTION 



Specific 
Gravity 
at 39 F. 


Degrees 
3eaume 
at 60 F. 


Degrees 
of 
Salom- 
eter at 
60 F. 


Pounds 
of Salt 
per Gal- 
lon of 
Solution. 


Pounds 
of Salt ' 

C P u 6 ft. 


Percent- 
age of 
Salt by 
Weight. 


Freezing- 
point 
Fahren- 
heit. 


Specific 
Heat. 


Weight 
per Gal- 
Ion at 
39 F. 


.007 


, 


4 


.084 


.628 


I 


31.8 


0.992 


8.40 


015 


2 


8 


.169 


1 . 264 


2 


29-3 


0.984 


8.46 


.023 


3 


12 


.256 


1.914 


3 


27.8 


0.976 


8.53 


.030 


4 


16 


344 


2-573 


4 


26.6 


0.968 


8-59 


037 


5 


20 


433 


3.238 


5 


25.2 


0.960 


8.65 


-045 


6 


24 


523 


3.912 


6 


23-9 


0.946 


8.72 


053 


7 


28 


.617 


4-615 


7 


22.5 


0.932 


8.78 


.061 


8 


32 


.708 


5.295 


8 


21 .2 


0.919 


8.85 


.068 


9 


36 


.802 


5.998 


9 


19.9 


0.905 


8.91 


.076 


10 


40 


.897 


6.709 


10 


l8. 7 


0.892 


8.97 


.091 


12 


4 8 


.092 


8.168 


12 


16.0 


0.874 


9.10 


US 


15 


60 


.389 


10.389 


15 


12.2 


0.855 


9 . 26 


155 


20 


80 


.928 


14.421 


20 


6.1 


0.829 


9.64 


.187 


24 


9 6 


376 


17.772 


24 


1.2 


0-795 


9.90 


.196 


25 


100 


.488 


18.610 


25 


o-5 


0.783 


9-97 


.264 


26 


104 


.610 


19-522 


26 


i.i 


0.771 


10.04 



COSTS OF INSTALLATION AND OPERATION TESTS 395 

Correction for temperature of aqua ammonia to reduce 
Beaume readings to 60 readings subtract | Beaume for the 
following number of degrees F: 

From 18 to 20 B. for each 8 F. above 60 F. 
From 20 to 22 B. for each 7 F. above 60 F. 
From 22 to 23^ B. for each 6 F. above 60 F. 
From 23! to 25^ B. for each 5 F. above 60 F. 
Above this for each 4 F. above 60 F. 



COMPARISON OF THERMOMETERS 



Cent. 


Fahr. 


Cent. Fahr. 


Cent. 


Fahr. 


-40 


40.0 


8 


46.4 56 


132.8 


-38 


-36.4 


10 


50.0 


58 


136.4 


-36 


- 3 2.8 


12 


53.6 


60 


140.0 


-34 


-2Q.2 


14 


57-2 


62 


143-6 


-32 


-25.6 


16 


60.8 


64 


147.2 


-30 


22.0 


18 


64.4 


66 


150.8 


-28 


-l8. 4 


20 


68.0 


68 


154-4 


-26 


-I 4 .8 


22 


71.6 i| 70 


158.0 


-24 


II .2 


24 


75-2 


72 


161.6 


22 


-7.6 


26 


78.8 


74 


165.2 


2O 


4.0 


28 


82.4 76 


168.8 


-18 


-0.4 


30 


86.0 78 


172.4 


-16 


+3-2 


32 


89.6 


80 


176.0 


-14 


6.8 


34 


93-2 


82 


179.6 


12 


10.4 


36 


96.8 


84 


183.2 


10 


14.0 


38 


100.4 86 


186.8 


-8 


17.6 


40 


104.0 


88 


190.4 


-6 


21 .2 


42 


107.6 


90 


194.0 


4 


2 4 .8 


44 


III .2 


92 


197.6 


2 


28.4 


46 


114.8 94 


2OI.2 





32.0 


48 


118.4 96 


204.8 


2 


35-6 


5 


I22.O 98 


208.4 


4 


39-2 


52 


125.6 ioo 


212. 


6 


42.8 


54 


129. 2 





TESTING REFRIGERATING APPARATUS 

Tests of refrigerating apparatus are difficult to perform 
because the changes of temperature in various parts of the appa- 
ratus are very slight, because the weight and quality of the 
refrigerating medium is difficult to determine and because the 



396 ELEMENTS OF REFRIGERATION 

errors at start and finish of the test make it necessary to carry 
the test over a considerable time. 

Tests are necessary to determine the effects or values of 
new devices and alterations and particularly to determine whether 
or not the guaranteed amount of refrigeration or the guaran- 
teed refrigerating effect has been obtained. 

To find the yield of the apparatus, the refrigerating effect 
may be measured from the ammonia or from the brine or in 
an ice plant the amount of ice produced may be found. If the 
guarantee is the production of a certain amount of ice or the 
cooling of certain rooms to a definite temperature with a given 
amount of power and cooling water this test is simple except for 
the length of test, which should never be less than twenty-four 
hours and would be much better if continued for one or two 
weeks. When, however, the refrigerating effect is to be found 
the test is difficult because of the quantities to be measured. 

The refrigeration produced from the ammonia is given by 

Q T = M(ii-K); 

M = weight of ammonia in given time; 

^ 1 =heat content in suction main leaving expansion coil; 

23= heat content at entrance to expansion valve. 

To determine this, the various factors on the right-hand 
side of the equation must be found. The weight of ammonia, 
M, may be found by collecting the ammonia in a receiver 
resting on a platform scale. This is connected to the piping sys- 
tem by a long piece of pipe so that there will be only a slight 
effect from the rigidity of the pipes. If the pipes are 10 ft. 
long the weight necessary to deflect the pipe an amount equal 
to the movement of the scale platform will be so small that 
little error results. By using two receivers, one may be filling 
while the other is being emptied. The ammonia may be col- 
lected in two tanks and the volumes measured, this being 
changed to weight by calibration. Care must be taken to have 
no pockets in the piping in which the ammonia may collect. 
In fact the uncertainty of the amount of ammonia which may 
lodge in pockets makes this method a difficult one and for that 



COSTS OF INSTALLATION AND OPERATION TESTS 397 

reason in some tests, such as those at the Eastman Kodak Co., 
the refrigeration is measured from the brine side. 

The quantities i\ and i 3 are difficult to determine if by chance 
there are liquid and vapor present together. To prevent this, 
the liquid going to the expansion valve is after-cooled so that 
it is below the temperature of vaporization corresponding to 
the pressure and must be all liquid (hence iz=qz'} and the 
vapor entering the suction valve is slightly superheated so that 
the quality may be determined by a thermometer 



In this way it is possible to find the value of ii and iz. The 
compression is dry compression. If it is desired to have wet 
compression it would be possible to have slightly superheated 
ammonia in the suction pipe and add an amount of liquid 
ammonia from a calibrated tank. 

The thermometers placed in the thermometer wells are 
subject to errors, due to the warming of the stem if any mercury 
projects above the well, and if none projects above there is 
difficulty in reading the thermometer, as the stem often freezes 
fast to the well on the suction side. To correct for stem error 
it is well to determine the temperature of the stem t s by a small 
thermometer tied to the stem and if t t is the reading of the 
thermometer, and /, is the reading of the point of the ther- 
mometer opposite the edge of the well so that the number 
of degrees exposed, above the well is t[ t w , the correction to be 
added to the reading is 

At = 0.000088 (t t - t s } (t t - Q . 

This assumes that the length (t t t w } is heated (t t t s ) 
degrees above the temperature it should have been 0.000088 
is the difference between the coefficient of expansion of glass 
and mercury. Constant immersion thermometers which have 
been calibrated to read correctly in rooms of a certain tem- 
perature when immersed to a mark on the stem may be used with 
no correction. 



398 ELEMENTS OF REFRIGERATION 

To save corrections and troubles in observation, thermo 
couples or resistance thermometers may be used. 

Calibrated gauge readings as well as temperatures are neces- 
sary on suction and discharge to determine the quantities i\ 
and is. The suction pressure is often measured by using a 
mercury U-tube so that small pressure differences may be read. 

On account of the errors in the method above, the refrigera- 
tion is sometimes determined from the brine, which is cooled 
by the ammonia. 



M b = weight of brine; 
c = specific heat of brine; 

to = temperature of brine at outlet from cooler; 
t t = temperature of brine at inlet to cooler. 

In this case the weight of brine M b is measured by weighing 
in large tanks; by the use of a meter which is calibrated at 
intervals during test; by the use of a Venturi meter or weir. 
The calibrations of these pieces of apparatus are absolutely 
necessary. 

The specific heat c must be determined by a formula from the 
specific gravity of the brine and the temperature or by tables 
given earlier or, what is better, by an experimental determination 
made in a Dewar flask by finding the watt hours used in a coil 
and required to warm a certain amount of brine between the 
temperatures used during the test. Corrections can be made 
for radiation by cooling curves and the water equivalent may be 
found by method of mixtures or by heating distilled water. 
In finding c by the formula or table the mean temperature 
is used and the specific gravity is determined by a hydrometer 
of some form. . . 

The temperatures / and / ( are subject to the same corrections 
mentioned before and because the difference between them is so 
small the thermometer should be graduated to tenths of a degree, 
or smaller, divisions. 

The use of Beckman thermometers would prove of value 
here. 



COSTS OF INSTALLATION AND OPERATION TESTS 399 

The power of the engine required to drive the compressor 
and the power of the compressor are determined by indicator 
diagrams. The small clearance on the compressor makes it 
necessary to use close and small connections for the indica- 
tors as the increase of clearance when the indicator is opened 
will change the form of card. It would be well to have a com- 
pensating volume to cut out when the indicator is connected 
or the indicator might be placed so that the piston would move 
vertically downward and the passage from the cylinder could be 
filled with oil so that this volume is not filled with ammonia. 
The usual formula for horse-power is used. 

It is necessary to test the springs and have the reducing 
motion correct. 

The amount of cooling water is weighed, metered, passed 
through an orifice or over a weir and its temperature is deter- 
mined by thermometers. The heat is given by 



In all cases the machines should be brought to an operating 
condition before starting the test and a running start should 
be made. With brine to determine refrigeration ten hours 
after steady conditions are obtained may be sufficient, although 
with ammonia a longer test must be used. In testing absorp- 
tion machines calibrated meters are used to determine the 
flow of liquor and the strength of the liquor is determined 
by drawing off samples and using a hydrometer to give the speci- 
fic gravity. Thermometers and gauges give the conditions at 
the various points. Meters are used to measure the cooling 
water and thermometers give the temperatures from which 
the heat may be determined. The drip from the separator 
may be determined by passing it into one of two cylinders and 
measuring its volume on the way to the analyzer. 

The test of ice plants should extend over a number of days 
five or seven, and in this test the ice is pulled at regular inter 
vals during the twenty-four hours. The test is started after 
the plant has been run at least seventy-two hours to get steady 
conditions. 



400 ELEMENTS OF REFRIGERATION 

General observations should be made at fifteen-minute 
intervals. These include the following: Temperatures: out- 
side atmosphere, engine room, refrigerated rooms, condensing 
water at inlet and outlet, brine at inlet to cooler and at outlet, 
ammonia at entrance to expansion valve and at entrance to 
suction main, at suction valve and at discharge main on com- 
pressor, at inlet and outlet to jacket; pressures on suction and 
discharge main, and in expansion coil, barometer; volume 
shown by meter on brine line, condensing water line and jacket 
water line, indicator cards, revolutions of compressor, weight 
of water going to ice tanks with temperature, weight of water 
left unfrozen, weight of coal, weight of boiler feed, feed tem- 
perature, calorimeter readings, flue gas temperature. 

The computation for such a test will be given in .the next 
chapter. 

For absorption machines -the readings are somewhat similar 
and are used in the same manner. 

A form of test has been discussed by the A. S. R. E. in its 
proceedings. 

The following data are obtained from a series of tests: 

RESULTS OF TEST ON DOUBLE-ACTING COMPRESSOR, MADE BY 
THE DE LA VERGNE Co. AT THE EASTMAN KODAK Co., 
DATE FEB. 5, 1908 

Temperature: Discharge ammonia R.H 149.44 F. 

L-H 143-36 F. 

Suction at compressor, before liquid 

injection i7.8oF. 

At brine cooler 19.40 F. 

Before expansion valve 58.91 F. 

Brine at inlet to cooler 25 . 11 F. 

Brine at outlet from cooler 14.81 F. 

Engine room 65 . 85 F. 

Ammonia receiver room 55 . 58 F. 

Outside atmosphere I 4-93 F. 

Revolutions in i5-minute compressor 512.1 

Revolutions in i5-minute brine pump 419 



COSTS OF INSTALLATION AND OPERATION TESTS 401 

Specific heat of brine o. 678 

Weight of brine per revolution 41.15 Ibs. 

Specific heat of liquid ammonia i . i 

Pounds of liquid ammonia in 15 min 236 . 6 

Pressures: Suction at cooler 20.45 

at compressor 20 . 03 

at condenser 185 . 06 

Steam at engine 84 . 1 1 

Barometer 15 .01 

M.E.P. Head end 38.95 

Crank end 39-67 

I-H.P.. 55-83 

Tons of refrigeration by brine 36 . 91 

Equivalent tons with 20 Ib. suction 36.88 

I.H.P. per ton i . 514 

Size of compressor. . .n|X 2 2 (2^ piston rod) double acting 
Size of engine 22X22 (3! piston rod) 

RESULTS OF TEST ON SINGLE-ACTING COMPRESSOR MADE BY 
THE YORK MFG. Co. AT THE EASTMAN KODAK Co., 
DATE MAR. 9, 1908. 

Temperatures: Discharge ammonia R.H 248.3 F. 

L.H 243- 3 F. 

Suction at compressor R.H 14 .34 F. 

L.H i 5 .2oF. 

At cooler 9 . 29 F. 

Before expansion valve 77 .91 F. 

Brine at inlet to cooler 22 . 73 F. 

Brine at outlet from cooler 13 .02 F. 

Engine room 64.80 F. 

Ammonia receiver room 73 .46 F. 

Outside atmosphere 24. 79 F. 

R.H. water jacket 180. 7 F. 

L.H. water jacket 168.45 F. 

Revolutions in i5-minute compressor 5 14 .7 

Brine pump 426 . 85 



402 ELEMENTS OF KEFRIGERATION 

Specific heat of brine o . 678 

Weight of brine per revolution 41 . 15 Ib. 

Pounds of liquid ammonia in 15 minutes 233 . 9 

Pressures: Suction at cooler 20.46 

at compressor 20.04. 

at condenser 187 . 27 

Steam at engine 81 . 96 

Barometer 14 . 95 

M.E.P.: Headend 36.56 

Crank end 37 . 09 

LH.P 52.57 

Tons of refrigeration by brine 37 . 01 

Equivalent tons with 2o-lb. suction 36.97 

I.H.P. per ton 1.42 

Size of compressor 15X22 (single acting) 

Size of engine 22X22 (3! piston rod) 

TEST OF Two DE LA VERGNE STANDARD HORIZONTAL RE- 
FRIGERATING MACHINES, DATE OCT. 27, 1910 

Temperatures: Ammonia discharge 245 .80 F. 

Ammonia suction at brine coolers . . 5 . o F. 

Ammonia before expansion valves. 8. 14 F. 

Brine at inlet 6 . 20 F. 

Brine at outlet 17.6 F. 

Revolutions of compressors 43-5 

Pressures: Suction 16 . 23 

At condensers 165 . 50 

Total horse-power 517.88 

Tons of refrigeration 373 . 23 

I.H.P. per ton i ..398 

Size of compressors double acting. . i&'><33" 

Size of engine 22 & 44X33 

Volumetric eff. : Apparent 95 .38 

True 82.15 

Rated capacity, two, 275 tons, 550 
tons 



COSTS OF INSTALLATION AND OPERATION TESTS 403 

TEST OF KROESCHELL BROS. ICE MACHINE Co.'s CO 2 COM- 
PRESSOR, DATE AUGUST 9, 1907 

Compressor, double acting, horizontal. 

Bore 138 M/M = s&" 

Stroke 508 M/M = 20" 

Piston rod 58 M/M = 2&" 

Speed 65R.P.M. 

Compressor gas displacement 54,914.6 cu.in. per min. 

Condenser pressure 65 atm. 

Evaporating pressure 23 atm. 

Evaporating temperature 5 F. 

Water temperature condenser inlet 53 F. 

Water temperature condenser outlet ... 81 F. 

Temperature of brine cooler inlet 25 .9 F. 

Temperature of brine cooler outlet 17 F. 

Quantity of brine pumped per hour .... 1000 cu.ft. 

Strength of brine 26 Beaume 

Estimated loss in brine tanks and cooler 10% 

Amount of refrigeration 50 . 76 tons 

Indicated power at engine 67 . 25 H.P. 

Indicated power at compressor 51 .3 H.P. 

Compressor gas displacement per ton per 

per min 1082 cu.in. 

Horse-power -f- cooling effect = i .010 

H.P. per ton of refrigeration. 

TEST OF VOGT ABSORPTION PLANT 

Aqua ammonia pump 5^ X 1 2 

Average speed pump 22 R.P.M. 

Temperature: Brine inlet 15 F. 

Brine outlet 13 F. 

Ammonia at condenser 105 F. 

Liquid from condenser 78 F. 

Strong aqua to rectifier 89 F. 

Strong aqua from rectifier 120 F. 

Strong aqua from exchanges 189 F. 



404 ELEMENTS OF REFRIGERATION 

Weak aqua from cooler ...................... 89 F. 

Cooling water .............................. 65 F. 

Cooling water from condenser ................ 72 F. 

Cooling water from absorber ................. 88 F. 

Cooling water from weak aqua cooler ......... 117 

Strong aqua at 60 F ........................ 26| Beaume 

Weak aqua at 60 F ........................ 23! Beaume 

Total cooling water per min .................. 252 gals. 

Ice per ton of coal .......................... 10.3 tons 

TEST OF WESTINGHOUSE-LEBLANC REFRIGERATING MACHINES, 
DATE AUG. 4TH AND 5TH, 1916 

Barometer .............................. 29. if 

Temperature atmosphere ................. 86 F. 

Live steam pressure ...................... 200 Ibs. per sq.in. 

Vacuum: ist ejector ..................... 29 

2d ejector ................. .... 28.95 

Condenser ..................... 27 . 80 

Temperature: Condensing water inlet ...... 82 . 5 F. 

Condensing water outlet ..... 92 F. 

Brine inlet ................. 18 .40 F. 

Outlet .................... 15.00 F. 

Weight of brine per hour ................. 19826 

Specific heat brine ........................ 833 

B.t.u. of refrigeration per hour ............ 56,202 

Tons per twenty-four hours ............... 4 . 60 

Loss by radiation ......................... 37 

Total loss ............................... 5 05 

Steam and vapor condensed per hour ....... 1125 

Vapor per hour .......................... 61 

Steam per hour .......................... IO 6 4 

Tons of refrigeration per ton of coal at 8 Ibs. of steam per pound 
of coal: 



1064 X?j* 
8X2000 



_ = = 
3 1.596 3 7 



COSTS OF INSTALLATION AND OPERATION TESTS 405 

TEST OF WESTINGHOUSE-LEBLANC APPARATUS FOR COOLING 

WATER. MARCH 24, 1915 

Barometer 29.18 

Vacuum in ist ejector 28 . 91 

Vacuum in condenser 27 .40 

Steam pressure (gauge) 125 

ist ejector 112.5 

2d ejector 110.5 

Quality 98.7% 

Temperatures : 

Water to be cooled (brine ordinarily) 

at inlet 40.5 F. 

at outlet 34 . 9 F. 

Steam, line 357-3 F. 

Atmosphere 69 . i F. 

Condenser, top 155 . 5 F. 

Condensate 89 . 7 F. 

Circulating water inlet 79 . 9 F. 

Outlet 89. 7 F. 

Weights per hour: 

Water to be cooled 101,320 

Circulating water 450,000 

Condensed steam 2513 

Heads pumped against 67 . 2 ft. 

Power brine pump 8 . 83 H.P. 

Condenser 35.7 H.P. 

Refrigeration 567,392 B.t.u. per hr. 



406 



ELEMENTS OF REFRIGERATION 

TESTS OF HART COOLING TOWER 



TEMPERATURE. 






Water 


Air. 






Gallons 


Rel. Hu- 






Above 


Below 


per Min. 


midity. 












Wet 


Atmos- 






Enter- 




Reduc- 


Dry 


Wet 


Bulb. 


phere. 






ing. 


Leaving. 


tion. 


Bulb. 


Bulb. 










78 


74 


4 


88 


72 


2 


14 


600 


41 


77 


71 


6 


88 


7 1 


O 


17 


600 


39 


81 


76 


5 


88 


74 


2 


12 


600 


46 


79 


7 6 


3 


84 


74 


2 


8 


600 


57 


82 


75 


7 


81 


73 


2 


6 


600 


64 


75 


69 


6 


7i 


67 


2 


2 


600 


78 


108 


76 


32 


87 


73 


3 


II 


1800 


46 


in 


73 


36 


76 


66 


7 


3 


1800 


55 


108 


76 


32 


81 


72 


4 


5 


1800 


60 


109 


78 


3i 


79 


73 


5 


i 


1800 


7i 


108 


74 


34 


74 


69 


5 





1800 


74 


83 


68 


IS 


77 


62 


6 


9 


3000 


4i 



CHAPTER X 
PROBLEMS 

THIS chapter is devoted to problems illustrating the appli- 
cation of the text. They are typical problems, and the student 
is urged to consider them as illustrating principles so that 
other problems of similar nature may be solved in the same man- 
ner. Certain problems are solved for a given set of conditions 
and if these conditions change the results will, of course, differ 
from those obtained. The general problems of design are repe- 
titions of certain fundamental problems and it has been the aim 
of the author to include these fundamentals in this set. The 
data to be used in actual problems must be obtained for the 
particular locality. 

Problem i. Find the best thickness of cork insulation for 
an 8-in. wall on a room which is to be held at 20 F. 

Cork thicknesses possible: 2 in., 3 in., two 2 in., 2 and 3 in., 
two 3 in., etc. 

Cost of i sq.ft. of cork installed (page 346) : 

2 in 25 cts. 

3 in 30 cts. 

4 in 40 cts. 

5 in 50 cts. 

6 in 60 cts. 

Value of i cu.ft. of storage space, per mo 5 cts. (p. 215) 

Cost of i ton of refrigeration 40 cts. (p. 376). 

Average outside temperature per year 48 F. (Fig. 166). 

Fixed charges (p. 379). 

Interest 8% 

Taxes i% 

Insurance i% 

Depreciation 3% 

Repairs 2% 

Total 15% 

407 



408 ELEMENTS OF REFRIGERATION 

Coefficient for 8-in. walls with plaster #" = 0.37 (p 211) 

C for cork 0.022 

C for plaster o. 46 

For completed walls the effect of additional layers of materials 
may be computed in the following way: 



-+-+- 

-fiT' = new constant; 
K = former constant for wall; 
/ = thicknesses of new layers; 
C = coefficients of new layers. 
(a) K for 8" brick, 2" cork, i" plaster. 

vt I 

K = -=0.095. 



0.37 12X0.022 12X0.46 
(b) K for 8" brick, 3" cork, i" plaster. 

r -*- 



=0.070. 



0.37 12X0.022 12X0.46 

(c} K for 8" brick, 4" cork, i" plaster (2", ", 2 /r , i x/ )/ 

^' = 0.055. 
(d) ^ for 8" brick, 5" cork, i" plaster (2", f", 3", i ;/ ). 

K' = 0.046. 
#ea/ 055 ^er Year in Tons of Refrigeration per square foot. 

(n \ 365X24X0.95(48-20) 

" - =.8iton; 

.6o ton; 



0.095 



PROBLEMS 409 



(c) o.8iX' 55 =o.47 ton; 

0.995 



= 0.39 ton. 



Cost of Refrigeration per Square Foot per Year. 
(a) 0.81X40 = $0.324; 

() 0.60X40= 0.240; 

(c) 0.47X40= o.i 88; 

(d) 0.39X40= 0.156. 
Cost of Space Required per Year. 

(a) -^XiXo.o5Xi2=o.i2o; 



(b) - 

(c) XiXo.o5X 12 =0.240; 



(d) XiXo.osX 12 =0.300. 



Yearly Cost of Insulation Investment per Year. 
(a} 0.25X0.15 =$0.037; 

(b) 0.30X0.15= 0.045; 

(c) 0.40X0.15= 0.060; 
(d} 0.50X0.15= 0.075. 
Total Yearly Cost. 

(a) 0.324+0.120+0.037 =$0.481; 

(b) = 0.456; 

(c) = 0.488; 
(d} = 0.521. 



410 ELEMENTS OF REFRIGERATION 

From the above it is seen that for the assumed conditions 
the 3-in. thickness is the best. If conditions (assumed data) 
be changed, a different result will be obtained. If space is 
worth i\ cents per cu.ft. per month, a wall made up of two 2-in. 
boards would be best. 

Problem 2, Find the space required to store the following: 
180,000 doz. eggs, 25,000 bu. potatoes, 200,000 Ibs. butter, 
200,000 Ibs. cheese, 25,000 bu. apples, 400,000 Ibs. beef, 200,000 
Ibs. mutton, 200,000 Ibs. pork, 20,000 Ibs. poultry, 500 crates 
celery, 2000 bbls. vegetables, 2000 boxes oranges and lemons. 

(a) Size Egg Room. 

-NT r 180,000 

No. of cases = =6000; 

3 

Volume of cases = 6000 X 2 \ = 13,500 cu.ft. ; 
Height of piles = 6 ft.; 

Net floor area =^^ = 2250 sq.ft.; 

Allow \ for aisles. 

Total floor area = 2 2 50 X I = 33 7 5 sq.ft. 

(6) Size Potato Room. 

No. of barrels = = 10,000 bbls.; 

..s 

Space required = 10,000 X 5 = 50,000 cu.ft. ; 
Height of piles = 8 f t. ; 



Net floor area = - = 6250 sq.ft.; 
8 

Allow 3- for aisles. 

Total floor area = 6250X1 = 781 2 sq.ft. 
(c) Size Butter Room. 



No. of tubs 



So 

Space = 4000 X 2 = 8000 ; 
Height of piles = 6 ft. 



= 4000; 



PROBLEMS 411 

AT , a 8OOO 

Net floor area = -- = 1 143 = 1 200 sq.ft. ; 
Total floor area = 1400 sq.ft. 

(d} Size Cheese Room. 

Same as (c), 1400 sq. ft. 

0) Size Apple Room. 

Same as (6), 7812 sq.ft. 

(/) Size of Beef Room. 

No. of halves of beef = - - - X 2 = 1070. 

750 

Assume these to be hung at i8-in. intervals and 3 ft. apart. 
Floor space = 1070X1^X3 =4800 sq.ft. 

(g) Size of Mutton Room. 

Assume carcass weighs 60 Ibs per cu.ft. in piles and that 
piles are 4 ft. high with aisles occupying one-quarter 
space. 



Floor space = - X = 1 100 sq.ft. 

(h} Size of Pork Room. 

Same as (g), noo sq.ft. 

(*) Size of Poultry Room. 

Same as (g), nob sq. ft. 

(j) Size of Celery Room. 

Total volume = 500 X 10 = 5000 cu.ft.jj 
Height of piles = 8 f t. ; 



Net floor area =- = 625 sq.ft.; 

8 

Allow ^ for aisles. 

Total floor area = 62 5X1 = 940 sq.ft. 



412 



ELEMENTS OF REFRIGERATION 



(k) Size of Vegetable Room. 

Space = 2000 bbls. X 5 = 10,000 cu.ft. ; 
Height piles = 8 ft; 



(/) 



Net floor area = = 1 2 50 sq.f t. ; 

o 

Allow \ for aisles. 

Total floor area = 1 250 Xf = 1600 sq.ft. 

Size of Orange Room. 

Space = 2000 X4 = 8000 cu.ft. ; 

Height = 5 ft; 

Net floor space = 1600 sq.ft. ; 

Allow i for aisles. 

Total floor area = 2000 sq.ft. 

The layout shown in Fig. 185 is suggested for this problem. 
The height of the stories would be 10 ft. in the clear. The 





Beef 
90 x 35 and 2-20 x 35 
30F. 


_R 


Pork 


Mutton 


35x16 


35x15 


30F. 


30F. 




6th Floor 6th Floor 

FIG. 185. Typical Warehouse. 



height of the building with a 4-ft basement and a 5-ft attic 
would give a total height of 75 ft. 



PROBLEMS 413 

Problem 3. Find the probable amount of refrigeration for 
the plant in Problem 2, assuming that all goods are received 
at 70 F. and that 90 F. is the warmest weather. Insulation: 
Main walls, 8-in. brick with two 3-in. thicknesses of cork at- 
tached with plaster and plaster finish. Partitions: 8-in. tile 
with plaster and 2 ins. of cork on one side, plastered. Floors 
at second story and ceiling of sixth floor: second figure, Fig. 108; 
other floors: brick arches with ^ = 0.25. 

(a) Temperature of Rooms. 

Eggs, 31 F.; Meat, 30 F.; 

Cheese, 32 F.; Apples, potatoes, vegetables, 36 F.; 

Butter, 15 F.; Oranges, lemons, 40 F.; 

Poultry, 20 F. ; Celery, 34 F. 

(b*) K'sfor Walls. 

K for walls (from p. 211) =0.039; 
K for partitions. 

K = - 1 -=0.081. 



0.022 0.46 

0.21 for tile with plaster, p. 211; 
0.022 from p. 193 for compressed cork; 
0.46 from p. 193 for plaster. 

K for floors. 

K = 0.062 p. 211 (second story); 

= 0.25 assumed for hollow arch bricks without 

insulation (3d to 5th); 
= 0.030 (p. 211), ceiling, top floor. 

(c) Heat Loss through Walls, Floors, Ceilings, Partitions. 
Heat loss from rooms in B.t.u. per hour. 



414 ELEMENTS OF REFRIGERATION 

FIRST FLOOR 
Holding room: 

Wall, 35 XioX (90-30) Xo.039 
Partitions (45 + 15 + 10+20+35) XioX 

(90 - 30) X 0.08 1 = 6750 

Floor 

Ceiling,35X35X(36-3o)Xao62l = 54Q 

loX 15 X (40-3) X 0.062 J __ _ 

8119 

Total for first floor 8lI 9 

SECOND FLOOR 
Celery room: 

Walls (55+35) XioX(90-34) Xo.o39 I9&5 

Partitions [35 X 10 X (36 - 34) + 20 X i o X 

(90-34)+35XioX(40-34)]Xo.o8i 
Floor 35X55X(90-34)Xo.o6 2 6684 

Ceiling [35X35 X(3i-34)+35_X 2 X 

(iS-34)]Xo.2 S = ~* 2 44 

5539 

Vegetable room: 
Walls (55+35)XioX(90-36)Xo.o 3 9 = 1895 

Partitions [35 X 10 X (34 - 3 6 ) + 2O 

Xio( 9 o-36)+35Xio( 4 o-36)].Xo.o8i 93 1 

Floor [ 3 5X3_5X(3Q-36) +20X35(90-36)] 

Xo.o62 = l888 

Ceiling ( 3 5X55)X(3i-36)Xo.2 5 = -2406 

2308 
Orange room I: 

Walls (55+35) XioX(9Q-4o) Xo.039 = i?55 

Partitions [35 XioX (36 -40) + 20X10 

X(90-4o)+35Xio( 4 oX4o)]Xo.o8i = 697 



+ 20 X 10 X (90-40)1X0.062 = 54io 

Ceiling 3 5X55X(32-4o)Xo.25 = 



4012 



PKOBLEMS 415 

Orange room II . 

Walls (55 +35) X 10 X (90 -40) X 0.039 = 1755 

Partitions [35 X 10 X (34 40) + 20 X 10 

X(QO 40) +35 X 10 X (40 4o)]o.o8i 640 

Floor 35 X 55 X (90- 40) X 0.062 5964 

Ceiling [35X35X(i5~4o) + 2oX35 

X(20 40)1X0.25 =11,156 

-2797 
Total for second floor 9062 

THIRD FLOOR 
(In the same manner as before.) 

Egg room 6,760 

Butter ror m 22,642 

Cheese room 5,3 J 8 

Poultry room . . 7,128 

Total for third floor 41,848 B.t.u. 

FOURTH FLOOR 

Beef room 12,433 

Mutton room 4466 

Pork room 742 

Total for fourth floor I0 \i57 B.t.u. 

FIFTH FLOOR 
Total for floor 22,632 B.t.u. 

SIXTH FLOOR 

Total for floor 23,5-54 B.t.u. 

Totals: 

First floor 8,119 

Second floor 9,062 

Third floor 41,848 

Fourth floor J6,i57 

Fifth floor 22,632 

Sixth floor 2 3>554 

122,372 

Tons Required: _H 2 j372_ = i Q 2 

60X199.2 



416 ELEMENTS OF REFRIGERATION 

(d) Heat from Goods. The greatest amount received at one 
time will have to be assumed together with the time required to 
reduce the goods to warehouse conditions. The cooling is 
assumed to take place in forty-eight hours. The greatest 
amount received at any one time is assumed to be the following: 

Beef, 40,000 Ibs. ; Butter, 6000 Ibs. ; 

Mutton, 15,000 Ibs.; Poultry, 2000 Ibs.; 

Pork, 2^,000 Ibs.; Apples, 300 bbls.; 

Eggs, 300 crates; Potatoes, 200 bbls. 

Heat Removed (see p. 215): 

From Beef : 40,ooo[(7o 30) Xo. 70+90] = 4,720,000 

Mutton: i5,ooo[(7o 3o)Xo.67+9o]= 1,752,000 

Pork: 25,ooo[(7o-3o) Xo.5o+9o] = 2,750,000 

Eggs: (3ooX5o)[(7o-3i)Xo.76] = 444,600 

Butter: 6ooo[(7o-i5)Xo.6o+84J = 702,000 

Poultry: 2ooo[(7o- 20) X 0.80 +102] = 284,000 

Apples: (300X1 50) [(70-36) X 0.92] = 1,407,600 

Potatoes : (200 X 1 50) [(70 - 36) X 0.80] = 8 1 6,000 



Total 12,876,200 

Tons Required: 12,876,200 = 22 4 

48X60X199.2 

(e) Heat from Lights (p. 341). 

In rooms 55X35 there would probably be ten 20- watt 
lamps. If six rooms are being used at one time the heat from 
these will be 

T 10X20X6X3.41 
= 



. ton. 
199.2X66 

(/) Heat from Men (p. 214). 
Assume 10 men working at one time. 



0.96 ton. 



199.2X60 

(g) Leakage through Doors. This is a difficult quantity to 
estimate and if the assumption is made that K = 2 and that the 



PKOBLEMS 417 

door area is 8X8 and that 10 of these may be open at one time, 
the following results: 



0199.2 

Totals: 



Walls 
Goods 


10-25 

22 4O 


Lights 
Men. 


34 
06 


Leakage. 


.yu 

6 20 







40.15 

If 33% excess is allowed for safety the total will be 54 tons. 
To check this, various general rules will be used. 

Volume of Building: 



From Peterson's rule, on p. 256, using 20,000 cu.ft. as the 
average size of the room and 30 as the average temperature: 

Cu.ft. per ton = 2. 5X1000 - -- =4000; 
L 5000 J 

4187^0 
1 ons required = '-^ = 104 tons. 

4000 

From average rule on p. 256: 

Tons required = - I --~= 1 40 tons. 
3000 

The difference in these results is due to the assumptions 
made. In the first case the insulation is heavy and the time to 
cool goods is moderately long. If this time were made less and 
the insulation poorer, the tonnage would be increased. In the 
general rules, there is no specific value for these items. 

In this problem two 30- ton machines should be installed. 



418 ELEMENTS OF REFRIGERATION 

Problem 4. Find the amount of radiation to be placed in 
the room for beef storage. 

Heat from walls = 1 2,433 B.t.u. per hr. 

Heat from beef = 4>7 6o >9 = I0 o,ooo B.t.u. per hr. 

45 

Heat from lights = 20X20X341 = J 3 6 4 B.t.u. per hr. 
Heat from men = 5 X 1150 = 575 B.t.u. per hr. 

Heat from door = 64X2 X6o = 7680 B.t.u. per hr. 

127,227 B.t.u. per hr. 
(a) Direct Expansion. 

t r =3F.; 
/ a =2oF.; 
# = 5 (P- 2 55); 



Using extra heavy 2-in. pipe, 1.608 ft. of length will give i sq.ft. 
Total Length = 2544X1. 608 =4100 lin. ft. 
From rules on pp. 255 and 256 the following is obtained: 

Volume of room ............... 45,500 

Temperature .................. 30 F. 

Allow f of 25 cu.ft. per lin. ft. on account of first freezing. 



Allow I of 35 sq.ft. per 1000 cu.ft. to allow for freezing in 
forty-eight hours- 

f t 

Lin. ft. = 23 50X1. 608 = 3 790 lin. ft. 

Amount allowed for room, 4000 lin. ft. This will be arranged 
in eight coils 37! ft. long and four coils 25 ft. long. Each coil 
will be five pipes high and two pipes wide. 



PROBLEMS 419 

(b) Brine. Surface, first method, using 7! difference in 
place of 10 will require 6100 lin. ft. 

Levey's table : Lin. ft. = ^^ = 4000 lin. ft. ; 
^Xiy 

Schmidt's table: Lin. ft. = 45 ' 5 X-X5oXi.6 = 546o lin. ft. 



Amount to be used, 6000 lin. ft. 

Problem 5. Find the length of 2-in. brine pipe with a drop 
of 5 and a mean temperature difference of 7^ F. between room 
and brine, assuring a 4-ft. per second velocity of brine. 

Internal area standard 2" pipe 3-355 sq.in. 

Outside circumference standard 2" pipe 7.461 in. 

Brine, sp.gr 1.119 

Specific heat 0.8 

K 5.0 

From (19) p. 259: 



1.119X0.8X5 

144 =4260 ft. 



In table on Fig. 255 it is noted that Levey suggests that 
these coils be made 275 ft. long. If such is done there will be 
different conditions from those noted: First, the velocity must 
be much less than 5 ft., and second the temperature drop will 
be less than 5 F. Of course, if K is taken as 10 instead of 5, 
there will be a decrease in length. If i ft. per second is used 
as velocity, and the drop is taken as 2, although the tempera- 
ture drop is 7^, and if K is used as 10, the length is found to 
be about 215 ft. 

L =4260 X T 5 oXirXf = 213 ft. 



420 ELEMENTS OF REFRIGERATION 

Problem 6. Find the velocity of brine in a 2-in. coil, 190 ft. 

long, if the mean temperature difference is 5 F., K = $, and 
temperature drop is 5 F. 



. 119X0.8X5 
I2 144 

^ = 0.127 ft. per sec. 

Problem 7. Find the amount of ammonia which will be 
evaporated in a 2-in. coil, 190 ft. long, of extra heavy pipe, if the 
ammonia is at 60 F. before throttling it to 20 F., and the 
temperature difference is 10 F. 

Heat from Pipe = 190 X -^ X 5 X 10 = 5900 B.t.u. per hr. 

Heat for i Ib. of Ammonia =(ii- is) =512.8(75) p. 69. 
HOT 60 F. and# = o = 30.9 
i for 20 F. and x = i = 543-7 

Pounds of ammonia per hour = ~ -- = 11.5 Ibs. 
Quality of ammonia after throttling to 



,. 

556.3 

Specific volume after throttling 

= 0.078 X 5.92 +0.922 Xo.0244 = 0.484. 
Velocity of mixture in 2-in. pipe at entrance: 

w= 11.93 Xf 4 8 sec. 

2.953X3600 

If longer pipes are used a greater quantity will be admitted 
and a higher velocity will be used. 

Problem 8. Find the amount of air to be admitted in an 
indirect system for the data of Problem 4 during the time of 
filling. Find the surface required in bunker coils. 



PROBLEMS 421 

Heat removed per hour = 127,227 B.t.u.; 
Temperature of room, 30 F.; 
Assumed temperature of air, 20 F. 

Amount of air per minute = - - = 10 602 cu f t 
10X0.02X60 

This assumes that air retains the same amount of moisture. 
Use i -in. pipes for bunker coils. Assume velocity of air 900 
ft. per minute. 

Area through clear space in bunker 

10,602 

= X 144 = 1700 sq. in. 
900 

If pipes are 6 ft. long and i in. is allowed between pipes, the 
number of sections will be 

1700 



.315 = 6.03, (14), p. 256. 
Air is cooled from 30 to 20 with ammonia at 15 F. 

MeanAJ =i5ll| = 9-i- 
fofrV 

o f 127,227 f 

Surface = - - = 2 ? 20 sq . f t. 
9-1X6.03 

or 2320X2.904 = 6750 lin. ft. 

Lines of pipe per section = 75 =47. 
24X6 

This excessive number of lines and surface is due to the small 
difference of temperature assumed. If a greater difference in 
temperature were used, the coil surface would be smaller, but 
the cost of compression would be greater, as a lower back pres- 
sure would be needed. 

This problem has not considered any change in moisture 
content. If this were taken into consideration, more surface 
would be required. The problem of heat and surface required 



422 ELEMENTS OF REFRIGERATION 

when there is a change of moisture content is given in Prob- 
lem 25. 

Problem 9. Find the size of ducts for air of Problem 8 
together with pressure drop, size of fan, and power required. 

Velocities in System (p. 248) : 

In register ..................... 300 ft. per min. 

In branches ................... 800 ft. per min. 

In main ...................... 1200 ft. per min. 

Size ofmain= I ^=8.& sq.ft., 4 'X2. 2 '. 

1200 

Assume main 80 ft. long with 5 bends, 4' X 2.2'. 
Assume branch 20 ft. long with 3 bends, 2' X i'. 



Loss in grill = 0.8x=0.31 (p. 250). 

Loss in branch =0.02 X X =0.83 (D 240) . 

4X0.33 64.3 

2Xl 



/8 QJ)\2 

Loss in 3 bends =3X0.15X^-^=1.24.' 
64-3 

Loss in main =0.02 X ---- - '""*"*"' = 2 
4X0.71 64.3 

8.8 



= 4.66 



Loss in 47 lines of pipe = 47 X 0.4 X = 6 <; 6 



Velocity head at end = = o ?.o 

64-3 



loss 76.54 ft. of air. 



PROBLEMS 423 

Oz. pressure =' '^ 4 = 0.606 (i 

no 

Inches of water =0.696X1.73 = 1.20. 

Dynamic pressure for Sirocco fan (p. 251) =^' uyu =0.977 oz - 

0.712 



Equivalent tabular volume for i oz. = 10,602.. /- I ^- = 10,7^0. 

\o-977 
No. 6 fan is the nearest fan in the table. 



Speed 



Discharge = ii,3OoX A / =11,150. 

\ i.ooo 



Power 



I.OOO \ I.OOO 



This fan is slightly too large, but using tabular values only it 
is the one which must be selected. 

Problem 10. Find the size brine main, size of pump, and 
power to pump brine for warehouse. 

For 60 tons capacity and 10 drop in brine, the weight of 
brine to be circulated per minute is given by (18) p. 259. 



M 6 = i498 Ibs. 

Volume per min. = ^^ - = 21.44 cu.ft. = 160 gal. per min. 
62.4X1.119 

Area main = ^-X 144 = 12. 9 sq.in. 

Use 4-in. pipe. Area, 12.65 sq.in. This gives a velocity of 
4.1 ft. per sec. 

Duplex pump size to discharge brine at 45 cycles per minute. 



424 ELEMENTS OF REFRIGERATION 

Assume 8-in. stroke. 



Diameter, 5! in. 

Use 6 X 8-in. brine end to pump. 

To find power to drive brine through warehouse it would be 
necessary to lay out all lines, branch circuits and compute losses 
in various parts. To find the approximate power it will be 
assumed that the 4-in. line extends to the top of the building and 
back again with 200 feet of pipe and eight right-angle bends, and 
the longest branch, near end, is 400 feet of 2-in. pipe with thirty 
right-angle bends. The velocity is 0.127 ft. P er second in the 
branch and 4.1 ft. per second in the main. The main has branches 
taken off from it at intervals and is, therefore, equivalent to a 
main of length equal to one-third of the length on line. 

From p. 260: 



.- 
64-3 0.33 64.3 

ft. 



, 

64-3 2 64.2 

There is no head lost in forcing the brine to top of the system, 
as the pipe is full. The slight difference in density, due to 10 
difference in temperature in ascending and descending pipes, is 
neglected. 

Total hydraulic 0^ = 2.27X1498 = 3410 ft.lbs. per min. 

Assuming 60% for the mechanical efficiency of pump, the 
power required to drive pump is 



I.H.P. ^ = o.i 72 H.P. 

33.000 



PROBLEMS 425 

Problem n. Find the size of supply main for liquid am- 
monia and return main for vapor for warehouse. 

Total ammonia per min. = a "' 2 = 23.3 Ibs. (See Prob. 7.) 

Volume of liquid at 60 F. = 23.3 Xo.o26o9 = 0.609 cu.ft. 

. . 0.600 
Area pipe = -^X 144 = 0.365 sq.m. 

Diameter =f". 

Use i" extra heavy pipe. 

Volume of vapor at 15 = 23. 3 X 6. 583 = 153 cu.ft. 

(a) From Velocity Considerations. 

Assume velocity 60 ft. per sec. (p. 257). 

Area = ^ X 144 = 6.1 sq.in. 
60X60 

Use extra heavy 3 -in. pipe. 

(b) From Pressure Drop Considerations. 

Assume \ Ib. drop in 50 ft. of pipe (p. 257). 



d J o. 

Use 3" for d within bracket. 

^ = 258. 

d =3.16. 

Use 3!" extra heavy pipe. 

Problem 12. Find the size of a freezing tank for a 50-ton 
plant using 3oo-lb. cans. 

Size of can from p. 290: 11^X22% at top, io|X 21^ at bottom, 
45 in. length over all, 44 in. length inside. 

Surface transmitting heat for 42 in. water depth 

= |2[llX42] + 2(22X42) + Io|X2l||TTT = 20.83 Sq.ft. 

Heat per hour with 20 brine and a coefficient of 3.3 B.t.u. 



426 ELEMENTS OF REFRIGERATION 

Heat from caw = 30o[i44.3 + (40 -32)] =48,390 B -t.u. 
(Temperature of water from cooler, 40; p. 308.) 
(Temperature of ice 20 F.) 

Hours to remove heat=~^- = 58.5. 
826 

By (3) p- 3 4: 

2 

Time to freeze ^-=46.3 hrs. 

These do not check, because the value of K used above is 
lower than can be used. If 4 were used in place of 3.3, the two 
would check. However, the previous value of 3.3 will be used. 
If now the temperature of the brine is reduced to 16 F. the 
heat removed per hour would be 

20.83 X (32 - 1 6) X3-3 = 1100. 
Hours=^390 = 44 hrs. 

IIOO 

Total cans per ton per day with 15% allowance 



From p. 305 it is seen that 14 cans are allowed per ton, 
but 1 6 cans are allowed by Shipley (p. 307). Using 16, the total 
number of cans would be 

Number of cans = 50 X 16 = 800 cans. 

If this is made 16 cans wide and 50 cans long the tank sizes 
will be 

Length = S o[ii| + i + i? + i] =62' 6"; 



Width = i6[ 

Depth = 45 "+6"= 4 '3''. 

Problem 13. Find the space required for a plate plant of 

50 tons capacity, using ammonia at 16 F. 



PROBLEMS 427 

Volume of ice per day = ^^=1740 cu.ft. 

Total length if 8-ft. depth and i2-in. thickness is used 

I74 O f. 

= =22O ft. 

1X8 
If 6 coils are used, giving 1 2 plates, the length is given by 



Using 1 2 -in. clearance the length of the tank will be 

i2Xi2"+6Xi2"+6"+6" = i 9 '. 
Tank size=i9 / Xi8| / X3 / . 

Time to freeze = ^ = 189 hrs. = 7.9 days = 8 days 

(P- 34)- 

Eight tanks will be required. 
Floor space = 43' X 92'. 
Problem 14. Find the coil surface required for the tank 

of Problem 12. 

Heat removed per pound of ice made = 200 B.t.u. (p. 308) .1 

., 150X2000X200 

Heat from coil= = 833,400 B.t.u. per hr. 

24 

Assume 10 difference between ammonia and brine. 
K = T.$ (p. 306). 

Surface of coil = ^' 4 = 5560 sq.ft. 

Linear feet of ij-in. pipe = 5560X2. 301 = 12,800 ft. 
From p. 307 the requirement would be 

Lin. ft. = 250X50 = 12,500. 
If 17 coils 60 ft. long are used the coils must be 13 pipes high. 

. . 12,800 

Number of pipes = =12.5. 
60X17 

This requires 41 in. of height if 3 centers are used. 



428 ELEMENTS OF REFRIGERATION 

Problem 15. Find the tons of refrigeration for plant of 

Problem 12, if 3 B.tu. are required for cooling. 

50 X 2000 X (200 +30) o 
Tons of refrigeration = -^^Oa^T" 

Problem 16. Find whether or not ice storage will pay with 
load curve shown on p. 309. 

Average machine capacity, 150- tons. 

Peak load capacity, 325 tons. 

Ice to be stored with 150 ton machine: 

May 25X31= 775 

June 65X30= 195 

July 175X31= 5425 

August 170X31= 527 

September 130X30= 3900 

October 55X31= J 75 

Total 19,025 tons - 



Volume of ice = ^ 025200 - = 662,ooo C u.ft. 

/ *D 

Size of house = 130 X 1 30 X4Q = 676,000 cu.f t. 
Cost of building = 0.06 X 676,000 = $40,560.00. 

(From p. 344.) 

Insulation, two 2" cork. 0.40X37,7= i5, 8o -- 

$55,640.00 
Yearly cost on building: 

Interest ......................... 6% 

Taxes and Insurance .............. i% 

Depreciation ..................... 5% 

Repairs .......................... T % 



13% of $55,640.00 = $ 7,233-20 
Cost of handling and holding = $0.25 X 19,025 = 4,75 6 -25 

Total cost of storing ice ........... $11,989.45 



PROBLEMS 429 

Cost of extra apparatus if no storage is used : 

175-ton compressor and engine with condenser, 
piping, receiver, oil separator. $ 23,000.00 

Boilers( I ^ X2 ^ X20 = 292 Boiler H.P.Y 
V 3 / 

including chimney piping, pump (p. 378) .... 9,000.00 

Cans, tank and coils 19,000.00 

Distilling apparatus 3,800.00 

Erection 9,000.00 

Additional building space 400,000 at 10 cts. 

(100X20X20) 40,000.00 



Total cost $102,800.00 

From p. 347, the cost per ton is $500.00, giving 

as the probable cost $ 87,500.00 

Amount assumed as cost 95,000.00 

With 8% depreciation and 3% for repairs the fixed charges 
willbei8%. 

Fixed cost per year = i 8% X 95,000 = $17,100.00 
Additional labor cost 1,500.00 



Total $18,600.00 

Saving by use of storehouse = $18,600 $12,000 = $6,600.00 

Problem 17. Find the cost per ton of pumping water for 

ice in a raw- water plant of 100 tons capacity if the water is 200 ft. 
below surface, using anthracite buckwheat coal. 

100X2000X1.15 , ,, 

Water per minute = - = 160 Ibs. 

24X60 

160X200 

Water horse-power = = 0.965. 
33,000 

(a) Power of steam end of deep-well pump = = 1.29 H.P. 

Steam required = 1.29X1 20 =I 55 lb. 

(P- 35I-) 



430 ELEMENTS OF REFRIGERATION 

Pounds coal per hour = ^ * C = 16. i 

12,800X0.75 

Tons of coal for water pumping per ton ice 



100X2240 
= 0.00172 ton. 

Cost of coal for pumping per ton of ice = 0.00 1 72X13.10 

= $0.00533. 
Cost of attendance per ton of ice (50 cts. per ton of coal) 

= $0.0008. 
Cost of pump end equivalent part of boiler, assumed 

$100.00. 

rrt r j , r . $IOO.OOXO.2O 

At 20%, fixed charges per ton of ice = 

365X100 

= $0.00055. 
Total cost of pumping per ton of ice = $0.00668. 

(b) Power for air-lift pump =^-^ = 2.41 H.P. 
0.40 

Pounds of steam per hour = 2.41X35 = 84. 4 Ibs. 
Tons of coal per ton of ice- 84.4X1000X24 



1 2, Soo.X 0.75X100X2240 

=0.00095. 

Cost of coal for pumping water per ton of ice = 0.00095 
X$3-io = $0.00244. 

Cost of attendance, = $0.00048. 

Cost of pump end equivalent part of boiler, = $250. 

Cost per ton of ice for fixed charges = 2 5Xo.2o 

100X365 
=$0.00137. 

Total cost of water pumping per ton of ice = $0.00429. 

Problem 18. Find the steam and surface necessary to evap- 
orate 40 tons of water per 24 hours, with steam at 5.3 Ibs. per 
sq.in. gauge pressure and of quality i.oo. 



PROBLEMS 431 

Temperature of steam at 20 Ibs. abs ........ 213 F. 

Temperature assumed in evaporator ......... 193 F. 

Pressure in evaporator, Ibs. abs ............. 9 . 96 

Vacuum in evaporator ..................... 9-7" 

Heat content of steam entering ............. i*57 7 

Heat content of steam leaving .............. U44-3 

Heat content of water at 193 F ............ 160.92 

External surface of evaporator, assumed ..... 250 sq.ft. 



Heat loss from 2 in. of 85% magnesia = 2 50 X[ 193 90] 

T2 

= 5408 B.t.u., using (i) p. 302. 



Af s (n57-7- l6o -9 2 )= [1144.3 -160.92] + 5408 
24 

= 3,278,000+5408 = 3,283,408. 

^^3,283,408 lbg hr 

996.7 

40X2000, , N 

(i 144-3 -160.9) 

Tube surface required = 40O ( 2I3 _ I93 ) = 4io sq.ft. 

This requires sixty-five 4-in. tubes 6 ft. long, using a drum 
about 5 ft. in diameter. 

Problem 19. Find the size of filter to be used for filtering 
the raw water for a ico-ton plant. 

100X2000X1728 

Water = Xi.i "5 = 19.1 gal. per mm. 

62.5X24X231X60 

Allow 2.5 gal. per min, per sq.ft. of filter (p. 287). 

Area of deck = ~^ = 7.6 sq.ft. = 1094 sq.in. Diam. = 38". 

Problem 20. Find the size of compressor to be used for a 
raw-water ice plant of 100 tons capacity. 
(a) Find Power. 

TOO tons requires 1600 cans of 3co-lb. capacity each . 
Air required = \ (1.8+0.3) =0.7 cu.ft. per min. per can. 
Total air = 0.7X1 600 = 1120 cu.ft. of free air per min. 



432 ELEMENTS OF REFRIGERATION 

Assume 90% for volumetric efficiency of a compressor 
running at 120 R.P.M. 

= 5-2 cu.ft. = 9000 cu.in. 



Use 2o"X3o". Displacement = 9560 cu.in. 

Power required = 0.4X10)0 = 40.0 H.P. (p. 296). 

Power required for air compressor by calculations to com- 
press 1 1 20 cu.ft. per minute to 18 Ibs. per sq.in. by gauge will 
be found to be 64 H.P. 

Problem 21. Find the power to drive the compressor 
required for Problem 15, the size of the compressor and parts, 
the amount of water for the condenser, and the condenser sur- 
face. Temperature of cooling water 65 F. (See pp. 72, 
et seq.) 

Temperature of evaporation ............ 6 F. 

Temperature of cooling water at inlet. . . 65 F. 
Temperature of water at point at which 

ammonia reaches the saturated state . . 80 F. 

Temperature of after-cooled liquid ...... 75 F. 

Temperature of ammonia in saturated 

portion of condenser ................ 90 F. 

Heat content of dry saturated ammonia at 

6 F .............................. 540 . i 

Entropy of dry saturated ammonia at 6 F. i . 1616 
Specific volume of dry saturated ammonia 

at6F ............................ 8.02 

Pressure at 6 F ...................... 34 . 60 Ibs. per sq.in. 

Pressure at 90 F ..................... 181 .80 Ibs. per sq.in. 

Heat content at 1 8 1.8 and entropy 1.1616. 644.0 B.t.u. 

Heat content of dry vapor at 181.8 ..... 558.9 B.t.u. 

Heat content of liquid at 90 F ......... 65 .3 B.t.u. 

Heat content of liquid at 75 F ......... 47 .8 B.t.u. 

Temperature of ammonia at end of com- 

pression ........................... 2 i i F. 

Specific volume at end of compression. . . 2.18 cu.ft. 



PROBLEMS 



433 



Amount of ammonia to produce 80.2 tons 

80.2X199.2 
= 540^47^ =3-5 Ibs. per mm. 

Power to drive compressor = 32.5(644.0-540.1) = IO ^ H p 

42.42X0.75 

The size of the compressor is fixed after the clearance is 
known. The clearance is made small so as to give a large volu- 
metric efficiency. The clearances of -^ in. on the upper end and 
| in. on the bottom end have been used on double-acting cylinders 
and in single-acting cylinders with a safety head -fa in.. and even 
6*4 in. have been used on the upper end, while that at the lower 
end may be anything. With small clearances the clearance 
volume will amount to about |%. 

As was pointed out earlier there is no effect of clearance on 
the work done, except in a slight degree, due to friction from 
longer strokes with larger clearances. The effect on volumetric 
efficiency is quite marked and hence, the amount of ammonia 
handled at a given speed and with it the amount of refrigeration. 
The York Mfg. Co. has performed a number of experiments on 
their double- and single-acting compressors with various amounts 
of clearance and has obtained the results given in the following 
table: 



COMPRESSOR I. H. P. PER TON FOR SINGLE-ACTING AND DOUBLE-ACTING COM- 
PRESSORS WITH VARIOUS CLEARANCES 





Clearance Volume 


H.P. at 


H.P. at 


H.P. at 


Linear 


in % of Displace- 


S Lbs. Suction 
Pressure 


15.67 Lbs. Suction 
Pressure 


25 Lbs. Suction 
Pressure 


Clearance 












S.A. 


D.A. 


S.A. 


D.A. 


S.A. 


D.A. 


S.A. 


D.A. 


A" 


0.24 




1-75 




1.30 




1.09 




A" 




0.42 




.18 




.60 




.26 


1" 


0.76 


0-85 


1.77 


34 


1.32 


.62 


I . IO 


.28 


1" 


I. 4 6 


i-55 


1.81 


45 


1-34 


.64 


1 .11 


30 


i" 


2.8 5 


2-93 


1.82 


56 


1.36 


.72 


I .12 


35 


i" 


5.63 


5-71 


1.83 .89 


J -39 


.01 


I - I 3 


44 



NOTE. S. A. Single-acting Compressor. 
D. A. Double-acting Compressor. 
Clearance Volume includes indicator connections, valve shut. 



434 



ELEMENTS OF REFRIGERATION 



TONNAGE PER 24 HOURS FOR SINGLE-ACTING AND DOUBLE-ACTING COMPRESSORS 
WITH VARIOUS CLEARANCES 



Linear 


Clearance Volume 
% of Displace- 
ment 


Tons at 
5 Lbs. Suction 
Pressure 


Tons at 
15.67 Lbs. Suction 
Pressure 


Tons at 
25 Lbs. Suction 
Pressure 














S.A. 


D.A. 


S.A. 


D.A. 


S.A. 


D.A. 


S.A. 


D.A. 


A" 


o. 24 




22.7 




38.0 




50-4 








0.42 




19.2 




33-0 




47-4 


\" 


0.76 


0.85 


22.6 


17-3 


37-2 


32.1 


50.1 


45-i 


\" 


1.46 


i-5S 


21 .O 


16.0 


35-6 


30.0 


49.1 


44-8 




2.85 


2-93 


19.7 


14-3 


34-4 


28.9 


47.0 


42-3 


i" 


5.63 


5-71 


15-5 


10.6 


29.7 


22.9 


42.6 


36-5 



For \% clearance the clearance factor is 

i 

/l8l.8\l-33 

1+0.0050.005! 1 =0.988 

If 5% leakage around valves and piston is assumed the 
volumetric efficiency is 

0.95X0.988=0.939. 

Displacement per min. = '- = 278 cu.ft. 

o-939 

The piston speed used in refrigeration work varies from 
140 ft. per minute in compressors of 5 tons to 500 ft. per minute 
with compressors of 300 tons capacity. These give 140 R. P. M. 
for the small compressors and 50 R. P. M. for the large ones. 
Using 2 compressors with 2 cylinders each at 80 R. P. M. the 
displacement of one cylinder is 

278 



Displacement = 

Sizes 10X19. 
12X13. 



2X2X80 



= 0.87 cu.ft. = 1500 cu.in. 



Either of the above might be used as 1he ratio of stroke to 
diameter used in practice varies from 2 to i to i to i. 

The cylinders are made of close-grain cast iron. They are 
designed to stand 300 per sq.in., using the ordinary formulae for 



PROBLEMS 435 

cylinder thickness. One-quarter to f in. is added for reboring. 
The upper portion of the cylinder is jacketed. 

Valves. The valves should be as large as possible. About 
2 5% of the piston area is sometimes found in valve area. The 
velocity through the valves may be used to determine the valve 
area. In this case 4000 ft. per minute is used in the suction 
valves where the increase of pressure is noticeable, while 
10,000 ft. per minute has been used through discharge valves. 
In any case make the area as large as possible. In single-acting 
compressors or their equivalent the suction valves are prac- 
tically as large as the piston. The discharge valves may be 
single large valves as in the Frick vertical or a number of smaller 
valves as in the Frick horizontal compressor. 

Pipe Connections. The pipe connections are of such a size 
that the velocity is 4000 ft. per second on the suction side and 
8000 on the discharge. 

32. 5X8.02 

144 = 4.7 sq.m. or 3-m. extra heavy pipe. 



F d ia = ^ . 2-I Xi44 = o.64 sq.in. or i-in. extra heavy pipe. 
2X8000 

Use 3-in. and 2-in. pipes. 

Pistons. The ammonia pistons are designed for 300 Ibs. 
per sq.in. They are made deep. The depth is about equal to 
the diameter or f the diameter of the piston. Some makers 
use three piston rings, ground to fit the ring groove, while others 
use four or five rings. The usual design of rings is made. The 
pistons are made of cast iron or steel. They are designed as flat 
plates supported by a series of beams. Empirical constants are 
found in handbooks of machine design. 

Piston Rod. The piston rod should be made of high-grade 
alloy steel and a factor of safety of 10 should be used. The rod 
is attached to the piston by a thread, using the piston as a nut 
or using a separate nut. The section at the root of the thread 
should be designed for tension. The main body of the rod is 
designed as a column. 



436 ELEMENTS OF REFRIGERATION 

Condenser. Heat removed in superheater portion per pound of 
ammonia = 644.0 -558.9 = 85. i B.t.u. 

Heat removed in saturated portion per pound of ammonia 

= 558.9-65.3=493-6 B.t.u. 

Heat removed in after cooler per pound of ammonia -65.3 
-47-8 = 17-5 B.t.u. 

Amount of cooling water per minute 
-- 1 no Ibs. 



= . 

48.05-33-08 

= 17.75 cu.ft. per mm. 

= 132.5 gal. per min. 
48.05=9' at 80 for water; 
33<0 8 = g' at 65 for water. 

Temperature of water at end of superheat is given by 

, M a (i 2 '-i2) 

q - qi= -~M^T 

, = 48-05+^ 

= 48.05 + 2.5 = 50.55. 
2=82.5. 

Temperature of water at end of aftercooler and entrance to 
saturated portion is given by , 



33.08+3- 



0.51=33.59; 

f-.65.5- 



Temperature Differences: 

At inlet aftercooler ........... 75 65 = 10 

At outlet aftercooler. . ., ...... 90 65.5 =24.5 

At inlet superheater .......... 90 80 = 10 

At outlet superheater ........ 21182.5 = 128.5 



PROBLEMS 437 

Mean Temperature Differences: 

For aftercooler AT = 2 4-5~io = l6 2 

, 3 ,o g ^ 

For saturated portion AT = 24.5-10 = 16.2 ; 

*** 

For superheated portion AT= I28 -5~ IQ =4 6. 3 . 

i 128.5 
2 . 3 log5 

If the water is forced through the double-pipe condenser 
at 5 ft. per second, the value of K would be 275, from Fig. 94. 
From formula (18) the value is 291 and by (20) it is 220 with 
2-in. and 3-in. pipes. On Fig. 188 the value of K is 100. The 
value of 200 will be used in the problem. 

F...= 60X32 - 5X493 ' 6 = 2 9 7 sq.ft. 

16.2X200 

For the aftercooler 400 will be used for K (p. 187). 

= 60X32.5X17.5 
16.2X400 

For the superheated portion (22) p. 188 gives K = $o. 

P 60X32.5X85.1 ,. 

F suv = - ^ -5 ^ = 122.0 sq.ft. 

46.3X30 

Total surface with | increase as safety factor = 566 sq.ft. 

The ordinary rules call for from 8 to 18 sq.ft. per ton. This 
would give 640 to 1440 sq.ft. The difference between 556 and 
640 is due to temperature difference. With water at tempera- 
tures taken 556 sq.ft. is sufficient. 

If the condenser is made up of 2-in. and 3-in. pipes and no 
allowance is made for cooling from the outside, the total length 
will be 

Total .length = 566 X i .608 = 910 ft. 

Number of stands of 12 pipes, 20 ft. long = m = 4- 



438 ELEMENTS OF REFRIGERATION 

In Block condensers 9 lin.ft. per ton is allowed. This 
requires about 720 linear feet. Shipley uses 8 ft. per ton in his 
improved condenser. Ordinarily with temperatures occurring 
in practice 25 lin.ft. per ton may be allowed in double-pipe con- 
densers of 2-in. and 3-in. pipes. In the problem just worked out 
about ii lin.ft. per ton is used. This is due to the velocity of 
the water and the assumed temperatures. 

Problem 22. If one-third of the refrigeration of Problem 21 
is possible at 20 F. in place of 6 F., find the size of compressor 
and power required for this if a Voorhees multiple effect in- 
stallation is used. 

Refrigeration at 6 F ................ 53.5 tons 

Refrigeration at 20 F ................ 26.7 tons 

Dry compression or x = i at discharge from coils: 

i"e ...................... 540.1 B.t.u. 

*"2o ----- ................. 543-7 B.t.u. 

i f 75 ...................... 47. 8 B.t.u. 

V 6 ...................... 8 . O2 CU.f t. 

^"20 ..................... 5.92 cu.ft. 

PG ...................... 34-6 

^20 ...................... 47-75 



53.5x199.3 

540.1-47.8 



M 2 ............... 26.7X199-2 =iog 

543-7-47-8 

Volume of cylinder for 21.7 Ibs. at 6 = 21.7 X8.02 = 174 cu.ft. 
Volume of i Ib. after adiabatic compression from 34.6 to 47.75, 
6.32 cu.ft. 

Volume of cylinder to care for addition at 20 = 21.7X6.32 
+ 10.8X5.92 = 201 cu.ft. 

If the compressor is built of 174 cu.ft. capacity, the 10.8 Ibs. 
of ammonia will not be drawn in at 47.75 lbs - pressure and the 
refrigeration cannot be done while a displacement of 201 cu.ft. 



PROBLEMS 439 

per minute would lower the back pressure in the lower system 
to 29.3 Ibs. per sq.in. and more work would have to be done. 

Specific volume = ^- = 0.28; 
21.7 

Pressure =29.3. 

This cannot be changed if it is necessary to divide refrigera- 
tion, as stated. 

Condition after mixing is given from specific volume. 

Specific volume = f f = 6. 18 ; 
Pressure =47.75 Ibs. per sq.in.; 

Temperature =35 F. (superheated 15); 
Heat content = 553-i; 
Entropy =1.153. 

After compression to 181.8 the conditions are- 

Entropy =1.153; 
Heat content = 638.0. 

Work of compression = (Mi + Af 2) (iz ~ii)+A(pi p )v 
= 32.5[638-553.i]+ T fs 144(47.75-29.3)201 
= 3453 B.t.u. permin. 

I.H.P. of motor = ^53 = 108.5. 

42.42X0.75 

The power required in Problem 21 was 102, so that this is not 
of any advantage on account of the lower back pressure. If, 
however, the load could be divided so that a smaller tonnage 
would be taken, at the higher pressure then there might be some 
economy. If 18 tons are used at the higher pressure the results 
are better. 

,, 62.2X199.2 

MI= = 25.1 Ibs.; 

492-3 

,, 18X199.2 
M 2 = = 7.2 Ibs. 
495-9 



440 



ELEMENTS OF REFRIGERATION 



Volume of cylinder for low pressure = 25.1 X8.O2 = 201. 
Volume of cylinder for high pressure = 2 5. 1X6.3 2 + 7. 2 

X5-92=20I.2. 

This checks and the system will operate. 

Specific volume of mixture at 47-75 lbs:= = 6.21. 

Temperature = 3 5 F. 
Heat content = 553.0; 
Entropy =i-i53- 

After compression to 181.8 at entropy 1.153 the heat content 
is 638. 



I.H.P.= 



42.42X0.75 
= 100.2. 

This means a saving of 2% over the simple arrangement. 
With other conditions this saving may be greater. 

Problem 23. Find the quantity of water at 60 F. which 
gives the most economic results if water for condensing is raised 
100 feet from a stream. . Use data in Chapter IX to fix costs. 
Assume temperature in coils to be 5 F. 

(a) Find cost of producing i ton of refrigeration if tempera- 
ture of condensation has different values by methods below. 



DATA COMPUTED FOR DIFFERENT QUANTITIES OF WATER 



t of condensation 


70 


75 


80 


85 


90 


95 


105 


p of condensation 


129.2 


141.1 


153-9 


167.4 


181.8 


197.3 


231.2 


v of compression 


1.1637 














i at beginning of comp 


539 9 














at end of comp 


621.3 


627.1 


633.5 


639.6 


645.2 


651.9 


666 '. o 


j of liquid at 68 F 


39.9 














/of water .'.... 


65 F. 


68 F. 


70 F. 


75 F. 


80 F. 


85 F. 


95 F. 


I H.P 


i .02 


I . IO 


1.18 


i . 25 


i .32 


i .41 


59 


Gallons per minute 


S.S6 


3.S2 


2.83 


1.91 


1.44 


1.07 


.85 


I. H.P. pump 


0.187 


0.118 


0.096 


0.064 


0.049 


0.036 


.029 


Steam per hour for engine. . 


24-S 


26.4 


28.3 


30.0 


31-5 


33-8 


3 -o 


Steam per hour for pump. . . 
Total steam per hour 
Cost of coal and labor in cts . 


28 
53.5 
1.07 


17.8 
44.2 
0.88 


14.4 
42.7 
0.85 


9.6 
39.6 
0.79 


7-8 
39-3 
0.79 


5-4 
39-2 
0.78 


.3 
4 -3 

-85 


Fixed charges on engine. . . . 


0.038 


0.041 


0.044 


0.046 


0.050 


0.052 


.059 


Fixed charges on condenser . 


0.014 


0.009 


0.007 


0.006 


0.005 


0.005 


0.005 


Total in cts per ton per hr. . 


1.227 


0.989 


0.955 


0.878 


0.872 


0.857 


0.930 



PROBLEMS 441 

The method of computing is given as follows: 

M = =0.398 Ib. per min. 

539-9-39-9 



42.42X0.75 



Gal per min. = 



(65 60^62.4X231 



... .. 

1728X33,000X0.75 

Steam consumption of engine on compressor, 24 Ibs. per 
I.H.P. hr. 

Steam consumption of pump, 150 Ibs per I.H.P. hr. 

Steam per hr. = 24 X 1.02 = 24.5. 

Steam per hr. = 150X0.187 = 28. 

Cost of buckwheat coal, $3.25 per ton. Cost of firing, 40 cts. 
per ton. Efficiency of boiler, 65%. Temperature of feed, 
200 F., pressure of steam 125 Ibs. abs. 

Cost of coal per 1000 Ibs. of dry steam 

_ iooo(i q } Xcost per ton 
" Heatperlb.Xeff.X224o ' 

.0- 167.951X365 



12,800X0.65X2240 
Cost of coal and labor = ~ X 20 = i .07 cts. 



Cost of fixed charges on compressor engine of 100 H.P. size 
based on 15% allowance and 8000 hours of use 

= $20.ooX 1.02X0.15 8 cts> 

8000 

There is no allowance for fixed charges on compressor, as com- 
pressor size is the same in all of these cases. 



442 ELEMENTS OF REFRIGERATION 

$300.00X0.15X0.187 
Fixed charges on pump = goQO = . 1 05 cts. 

, 0.398 (i 2 - is) X 60 

Condenser surface 



:8.6 sq.ft. 
100X7-5 

Cost of condenser at 40 cts. per sq.ft and 15% for depreciation, 

18.6X40X0.15 

taxes, etc., and 8000 hours = =0.014. 

8000 

From the total of cost it is seen that 1.07 gallons per minute 
is the most economical rate. If now instead of having water free 
from a stream it must be purchased at 3 cents per 1000 gallons, 
the sums above are increased giving the following table: 



Gallons per minute 
Cost for water free 
Cost of water 

Total cost with water 


1.227 

I.OOO 


3-52 
0.989 

o'.632 


2.83 
0-955 
0.510 


1.91 
0.878 
0-344 


1.44 
0.872 
0.259 


1.07 
0.857 
0.193 


0.85 
0.930 
0.153 


2.227 


1.521 


1-465 


I .222 


I.I3I 


1.050 


1.083- 



Cost of water 



The result is the same as before, although, if these results are 
plotted into a curve, the most economical rate will be found 
higher. At 6 cents per 1000 gallons the total cost at 1.07 
gallons would be 1.243 cts - against 1.236 at 0.85 gallon; show- 
ing that at this cost for water, the cost of water would offset 
the additional cost of power. 

Problem 24. Find the size of cooling tower to cool the 
water required in Problem 22 for 80.2 tons of refrigeration with 
102 H.P. and a steam consumption of 25 Ibs. of steam per 
horse-power hour. The water is to be cooled from 95 to 60 F. 
in 70 weather, with the wet bulb temperature of 60 F. 

Amount of water from ammonia condenser = 1.07X80. 2 
= 85.8 gallons per min. 



PROBLEMS 443 

Amount of water from steam condenser 

_ 102X25X1000 1728 

35X60X62.4 231 

Total water per minute to tower = 228. 8 gallons = 1910 Ibs. 

Relative humidity from Fig. 92 0.49 

Relative humidity at discharge i . oo 

Temperature of air at entrance 70 F. 

Temperature of air at discharge 95 F. 

Temperature of water at entrance 95 F. 

Temperature of water at discharge 60 F. 

Barometric pressure 14.7 

Assume volume of air at entrance i cu.ft. 

Weight of moisture at ew/rawce = 0.0011 53 X 0.49 = 0.000564. 
Volume of air at discharge 

= 144(14.7-0.49X0.3628) ^ (460+95) = z 
460+70 (14.7-0.815)144 

Moisture in air leaving = i .095 X 0.002474 = 0.002 7 1 Ib. 
Moisture absorbed 0.00271 0.00056 = 0.00215 Ib. 
Assume water entering when i cu.ft. of air enters is equal 
to m". 

Energy Entering: 

With water, w"x63.oi =63.01 m"\ 

With air, M x i44(i4.7-o.49Xo. 3 628) = 

0.4 778 

With moisture, o.ooo565[io8i .5 + (70 50)0.6] = 0.62. 

Energy Leaving: 

With water, (m" -0.002 15) (28.08) = 28.08^"- 0.06. 

With air, L4 x i44(i4.y-a8is)i.og5 = 
0.4 778 



444 ELEMENTS OF REFRIGERATION 

With moisture, 0.00271X1102.3 = 2.99. 
Equating: 
63.01 ^"+9.42 +0.62 = 28.08 ^"-0.06+9.86 + 2.99. 



12.7 cu.ft. of air must be taken in per Ib. of water entering. 
12.7X0.00215 = 0.0273 Ib. moisture absorbed per pound 

entering. 

Total air per minute = 12. 7X1910 = 24,200 cu.ft. per min. 
With a velocity of 700 ft. per second, this would require a cross- 
sectional area of 

= 35 sq.ft. (5'X/.) 



An atmospheric tower would require 

228X1 = 228 sq.ft. (15X15'.) 
A cooling pond for this plant would contain 

228X70 = 15,960 sq.ft. (160X100'.) 
The basin for spray nozzles would contain 

228X2 = 556 sq.ft. 

There would be a set of four 2^-in. nozzles, as each would 
care for about 70 gallons. Two sets would be required for 35 
cooling. 

Problem 25. Find the amount of refrigeration, surfaces 
for brine cooler, condenser and bunker, and fan size for the 
air conditioner for a 450-ton furnace (450 tons per day), when 
the air is at 90 F. and the wet bulb shows 85 F. 
(a) Refrigeration: 

Relative humidity (Fig. 93) ........ 0.82 

Partial vapor pressure = 0.82 X .698. . 0.57 

Temperature of air leaving ......... 34 F. 

Assume air required per minute ..... 40,000 cu.ft. 



Volume of air leaving = 40,000 X Mii 1 ^ ~-57; 

(460+90) 

x _(46o 34) = 
144(14.7-0.0961) 



PROBLEMS 445 

Weight of air entering = ^ X * 44 X (l ^ =2790 Ibs. 

53.35X550 

Weight of moisture entering = 40,000 Xo.82 Xo.oo2i37 

= 70 Ibs. 

Weight of moisture leaving = 34, 900X0.000327 = 11.4 Ibs. 
Water condensed per minute = 58.6 Ibs. 

Water condensed per day 58.6X60X24X1728 = ^ } 

62.4X231 
Entering: 

Energy in air at entrance above 32 F. 

= 0.24X2790(90-32)= 38,900 
Energy in moisture at entrance above 32 F. 

= 70 X [1097. 3 + (90 -34)0.6]= 77,063 

Total ............................... 115,963 

Leaving: 

Energy in air at exit above 32 F. 

= 0.24X2790(34-32= 1335 
Energy in moisture at exit above 32 F. 

= 11.4X1074= 12,250 
Energy in water at exit above 32 F. = 58.6X2.01 = 118 

Total ....... . ........................ i3>73 

Heat removed, 115,963 13,703 = 102,260 B.t.u. per min. 

102,260 
Tons of refrigeration for air alone = - = 513 tons. 

(b) Surfaces required: 

Air temperature entering, 90 F. ; 
Air temperature leaving, 34 F.; 
Brine temperature entering, 24 F.; 
Brine temperature leaving, 39 F. 



Mean Ar = - = = 

'lo. H 2 - 12 



446 ELEMENTS OF REFRIGERATION 

Assume velocity of air 900 ft. per min. 



102,260 X6o = 
19-4X8.5 

Use 2-in. pipes, 20 ft. long. Pipe surface = 2oX ~r~o = I2 -45- 

Number of pipes = - = 3060 pipes. 
12.45 

If sections are made up of sections 25 pipes high and 3 sec- 
tions above each other, the number of rows will be 

Rowi.J252.-4i. 

3X25 

Area for air = = 44.4 sq.ft. 

Width between rows of tube= 44 ' 4 X 12 =0.65". 
41X20 



Total length = --i2- 4 f". 

If three division walls or plates are placed in bunker, this 
may be made 13 ft. o in. long. 

The width of bunker will be 30 ft. to allow 5 ft. at each end. 
The height will be 

75(4" centers) +3X6" = 26' 6". 

The heat loss from bunker with 3-in. cork insulation on i2-in. 
brick will be 



2340X oo- Xo.o; =4580 B.t.u. 

(K = o.oj, p. 211). 



Tonnage in radiation = = 21 tons. 
199.2 

Tonnage in brine = 513+ 23 = $36 tons.* 



PROBLEMS 447 

Brine coils: 

Assume ammonia at 9. 

Mean AT = takl?4^) = _i5_ = o 
log, f 0.692 

Assume velocity of 5 ft. per sec. From Fig. 95, # = 137. 

^536X199.2X60 ft 

137X21.7 

Using ii-in. pipe 20 ft. long and 10 high for one coil, the 
surface per coil will be 

2coX - = 99-5 sq.ft., 

2.OI 

Number of coils = 22 coils. 
99-5 

With no circulation in pipe the rules on Fig. 189 would 
require 29,315 sq.ft., but in this rule the temperature difference 
is small. 

Suppose brine tank is 20X11X8 ft. The surface will be 
936 sq.ft. and the heat loss will be 



9 3 6Xo.o 7 X 9 o- =3800. 



Tons of Radiation =- -- = 19 tons. 
199.2 



Total toage = 536 + i9 = 555 tons. 

Condenser $;/# = 55 5X40 = 2 2, 200 sq.ft. If the ammonia 
were in condition of Problem 21, the surface would be 

555X7=3885 sq.ft. 

This would require 12 stands of 2- and 3 -in. double pipe con- 
densers, each 10 high and 20 ft. long. 

3885 

J 5 =12.1. 



20XIOXI.608 



448 ELEMENTS OF REFRIGERATION 

(d) Fan Size. Pressure in actual plants (p. 321) = 1.2 oz. 
Use Buffalo conoidal type. 
Pressure 1.2 oz. 

Equivalent volume at 2 oz. = 40,000^- - = 51,600 cu.ft. per 

min. 

Use No. 130 fan; 



= 226; 



Actual quantity = 64,700 = 50,000; 



2 64,700 



27.1 H.P. 



The fan is larger than required, but it is the nearest that can 
be obtained from table. The fan would be 129 in. high, 6 ft. 
6 in. wide and 109! in. long. 

Problem 26. Find the amount of refrigeration and power 
to operate a water-cooling system to supply 1000 men in a plant 
when the length of the circuit is 5100 ft. arranged in parallel 
circuits 1700 feet long with 20 elbows. The water is 75 in 
90 weather. 

Men on i shift ............ 600 

Quantity of water ......... 600 X| = 150 gals, per hr. 

= 50 gals, per hr. in circuit 

= 412 Ibs. 
Number of fountains ....... - 6 ^- = 20 

Length of pipe at each fountain, 20 ft. 

Total length of i circuit, 1700+^X20 = 1840 ft. 

Elbows in i circuit = 4X7 + 20 = 48. 

(a) Refrigeration: 

Mean temperature of water, 50 F.; 

Drop in line temperature, 5 52.5 to 47.5 F. 



PROBLEMS 449 

Using ice water covering and assuming i^-in. pipe, the heat 
loss is 

Q = 1840X0.23(90 50) = 16,900. 
Weight of water to care for radiation with 5 fall 

16,900 

= 3380 IDS. per hr. 

Area required to give 3-ft. velocity (30), p. 335. 



Fp = 0.00562 =0.8 1 sq.in. 
Use ij-in. pipe. 
For i|-in. pipe 

Velocity = 3792Xl44 = 1.2 ft. per sec. 

3600X62.4X2.036 

Total refrigeration in pipe and water 

= = 6.8^ 

199.2X60 

Loss in two storage tanks of 6 ft. diameter, 10 ft. high 
= 220X0.07X40 = 617 B.t.u. per hr. =0.05 ton. 
Total tonnage = 6. 88 tons. 

(6) Power required: 

=[(i&f + * SlfeH- 

L\I2 / 12 J 

:O.II5H.P. 



33, ooo X 60 X. 60 
UseiH.P. 

Problem 27. Using data from test of Feb. 5, 1908 (p. 400), 
reduce refrigerating effect. 
(a) From brine: 

Weight of brine per revolution of pump ... 41.15 Ibs. 
Revolutions of brine pump in 15 min ...... 419 

Weight of brine per minute, ^^ ^^ = 1 150. 



ELEMENTS OF REFRIGERATION 

Temperature of brine at inlet to cooler ...... 25.11 F. 

Temperature of brine at outlet from cooler. 14.81 F. 
Specific heat of brine .................... - 6 7 8 

Heat removed per minute 

= ii 5 oX(25.n -14-81) X 0.678 = 8049- 

8040 
Tons of 



I.H.P .......... ........... 55.83 

"^.83 
I.H.P. per ton ..................... ^of = I ' 39 

(&) From ammonia: 

Mean discharge temperature .......... 146 -4 

Discharge pressure by gauge .......... 185 . 06 

Barometer .......................... i5- QI 

Absolute pressure .................... 200.07 

Temperature of saturation ............ 95 . 9 

Heat content at 185.06 Ib. and 146.4 F. 595.9 
Temperature at expansion valve ........ 58.9 1 F. 

Heat content of liquid at 58.91 F ..... 29.8 

Temperature in suction ............... 17 . 80 

Pressure of suction ............. 20.45 

Barometer .................... 15 . 01 

Absolute pressure .................... 35 . 46 

Temperature of saturation ............ 6.5 F. 

Heat content at 3 5. 46 Ibs. and zy.ST. . . 547 

Ammonia per minute 23 ' =15.8 Ibs. 
Refrigeration = i5-8[547 - 29.8] = 8180. 

Tons of refrigeration, - =41.2. 
199.2 



PROBLEMS 451 

This is slightly greater than the brine result. 

Cooling = 15. 8(595. 9 29. 8) =8960 B.t.u. per min. 

Problem 28. Check data from test of Westinghouse-Leblanc 
machine. 

Refrigeration = -~ X o. 833 X (18.40 15.00) =935.8. 
oo 

Tons of refrigeration, 935 ' =4.69. 
199.2 



INDEX 



PAGE 

A 

Absorber 32, 137 

, tubular 37 

Absorption machine 3 1 , 79 

system 49 



Accumulator. . 



279 



Adiabatic, construction of 114 

After cooling 69 

Air 105 

blower 295 

circulation 245 

compressors, cost of 351 

cooling 318 

of churches, hotels, auditoriums 322 

drying 319 

drying design 444 

for cooling tower 176 

leakage, heat of 213 

lift pump 298 

machine advantage 21 

operation 25 

work of compression 20 

pump 283 

quantity 248, 254 

refrigerating machines 18 

required for raw water ice 295 

required for room 420 

supply header 295 

system closed 19 

open 20 

velocity 248 

Allen 24 

Allen dense air machine 19 

Ammonia compressors, cost of 351 

evaporated, in coil 420 

main, size of 425 

required 257 

Amount of refrigeration for ice making 310 

Analyzer , 33 

453 



454 INDEX 



Apples 22 7 

Applications of refrigeration 3 12 

Aqua ammonia ^ 

, partial pressure 80 

, specific heat 83 

, specific gravity 83 

, temperature of boiling 80 

Arctic machine I2 5, 126 

Audiffern-Singrun, machine I3 1 

Auditorium air cooling 3 22 

Automatic refrigeration 263 

Automobiles, use of 3" 

B 

Bananas 229 

Baudelot cooler 314 

Beal 297 

Bell-Coleman 21 

Belting, cost of 352 

Berthelot 81 

Bertsch 167 

Binary refrigeration 169 

Blast furnace application 318 

Bohn ice box 13 

Boilers, cost of, dimensions of 348, 363, 365 

Boiling-point 2 

Boyle Union 142 

Branch tees 141; 

Brewery 241, 314 

, refrigeration for. 317 

Brine 258 

, amount of 259 

cooler 160, 163, 164, 306 

, forcing 250 

freezing tank 273 



kind of 



259 



pipe and pump, size 

, specific heat 2 ^g 

system 27 245 

tank 34 

tank coil 259 

velocity determination 420 

Buildings, cost of ,4, 

Bunker _ 247 

piping 256 

room , 323 

surface, determination of 42I 



INDEX 455 



PAGE 

Cabbages 229 

Candling 220 

Candy 312 

Cans, cost of 357 

Can filler 274 

, ice : 289 

, number of 305 

required 426 

surface 310 

system 269 

Car, precooling 264 

refrigerated data 381 

refrigerator 13 

Carbondale machine 36 

Carbon dioxide machine 31, 105, 128 

properties 390, 391, 392 

Carpentering, cost of 344 

Carrg 37 

Carr6 Machines 4 

Carrier 51 

Carrier's chart 175 

Celery 229 

Cement wall 201 

Central refrigerating plant 260 

station load 262 

Characteristic equation 62, 64 

Cheese 223 

Chemical work 337 

Chocolate, specific heat 313 

Church air cooling 322 

Cleanliness of plants 303 

Clearance 433 

effect 44, 71, 433 

factor 46 

Clothing 229 

Closed air system 19 

Coefficient for brine pipes 306 

of transmission of pipes 255 

Coil, cooling 18 

, cost of 35 2 . 353 

, data for 3S 2 , 353 

surface 3 1Q 

, amount of 254 

, required 4 2 7 

, testing 123, 124 

Coke filter. . . 3o 



456 INDEX 

PAGE 

Cold storage ......................................................... 2I 7 

, average length of time .................................... 219 

for brewery .............................................. 241 

for florists ............................................... 231 

,for hotels ................................................ 238 

for markets .............................................. 232 

for packing houses ........................................ 239 

for ships ................................................ 240 

heat loss ................................................ 243 

laws .................................................... 217 

products, value of ........................................ 217 

with ice ................... . .............................. 241 

warehouses ...................... ........................ 5 

Cole. I. & W ............................... . ........................ 26 

Comparison of thermometers ............................ ............... 395 

Complete absorption, heat of .......................................... 81 

dilution, heat bf ............................................. 81 

Compressed air machines .............................................. 4 

Compression, dry ..................................................... 68 

, machines ................................................ 4 

refrigerating machine ..................................... 26 

, wet ..................................................... 68 

Compressor air, size required ........................................... 431 

, cost of ................................................ 351 

, ammonia, cost of ....................................... 351 

, size required ....................... .......... 432 

, arctic ................................................. 125 

, De la Vergne ................................... 29, 116, 118 

, dimensions of ................................. 358, 360, 361 

, exhausting ............................................ 125 

, Frick ................................... x ........... 28, 122 

, power required ........................................ 432 

, single acting ........................................... 27 

.York ................................................. no 

, aqua ammonia ......................................... 31 

Condenser ..................................................... 31, 32, 149 

Block, cost of ...... ..................................... 352, 353 

> data for .............................. ........... 352, 3S3 

, De La Vergne ........................................ 154 

, design ..................................... ............... 43 6 

, double pipe ................................................ 37 

, exhausting ................................................ I2 ^ 

, flanged ................................................... l $ 2 

, Philadelphia ............................................... I57 

, oval flask steam ............................................ ^ 



screwed 



53 



.Shipley .............................. _ I5 g 



INDEX 457 

PAGE 

Condenser, submerged 155 

, supports 159 

, surface steam 165 

, welded 151 

Conduction ' 182, 183 

Conduits 261 

Congealer 233 

Constant quality 58 

vapor weight line 58 

volume line 59 

of transmission ^7 

Construction warehouses 231 

Cool brine system 5 

Cooler for sweet water 241 

Cooling 46 

, by evaporation ! 

, by solution i 

, by ice 3 

, determination of 399 

, drinking water 331 

method of 244 

pond 172 

pond design 1 78 

tower 167, 169 

lower design 1 76, 442 

tower test 406 

water 374 

Cool water coil 32 

Cooper system of refrigeration 18 

Cork, best thickness 407 

board 201 

covering 336 

loss . . 334 

Correction for hydrometer 395 

of thermometer readings 397 

Cost of air compressors 351 

ammonia compressors 351 

belting .... 352, 353 

fan blowers 352 

boilers 348 

buildings 343 

cans 357 

carpentering 344 

coils 352, 353 

condensers 352, 353 

distilling apparatus 357 

electric generator 350 



346 



458 INDEX 

PAGE 

Cost of electric motors 35 

engines 349 

excavations 34 

floors 34S 

gas engines 35 

ice, natural 3 8 4 

, manufactured 34 

storage 39 

insulation 345, 346 

land 343 

lumber 344 

machinery 347 

masonry 344 

millwork 345, 395 

miscellaneous apparatus 357 

operating 376, 377, 378, 379 

partitions 345 

painting 345 

plumbing 345 

pipe and fittings 354 

pipe coverings 

pipe for storage 357 

plant, initial 376, 377, 3?8, 379 

plumbing, initial 345 

producers 348 

pumps 35 r 

receiver .' 353 

roadway 345 

roofing 345 

separators 353 

space 49 

storage 215, 375 

supplies 357, 374 

switchboard 35 

water .' 374 

Counter current flow 47 

Curves, construction of US 

Cream 225 

Creamery refrigerators 339 

Crosses 145 

Curve of ice consumption 308 

Cushionhead 109 

Cycle diagram 66 

Cylinders 116, 120, 122, 434 

Cylinder expansion IQ 

head 29 

operation of 123 



INDEX 459 



PAGE 

Dairy refrigeration ' 339 

Data for coils and condensers 352, 353 

engine 349 

gas engine 350 

ice cream 382 

ice delivery 380 

ice storage plant 310 

Pipes , 355, 356 

pumps, 351 

rinks 382 

turbines 349 

warehouse 383 

Deepwell pump 298 

Dehydrator 33, 34 

De la Vergue 116, 118, 120 

machine 30 

freezing tank 273 

Dense air machine: 57 

Density of salt 258 

Deodorizer 284 

Depreciation 206, 379 

Design of pistons 435 

piston rod 435 

Determination from Le Blanc machine test 451 

amount of ammonia and air 420 

amount of water for condenser and power 43 2 

of best quantity of water 440 

of best thickness of cork 407 

brine pipe and pump 423 

bunker surface 421 

coefficient of wall 408 

coil surface 427 

condenser surface 436 

cooling 399 

cost of pumping 429 

data for air drying 444 

fan and power 422 

heat loss through walls 413 

ice storage 428 

length of pipe 419 

multiple effect installation 438 

number of cans 426 

pipe sizes 435 

plate plant 426 

radiation 418 

refrigeration 396, 398, 428 



460 INDEX 

PAGE 

Determination refrigerating effect test 449 

size of air compressor 43 * 

size ammonia main 4 2 S 

size of cooling tower 44 2 

of size of evaporator : . . 43 

size of filter 431 

size of freezing tank 4 2 S 

specific heat 39$ 

storage space required 4! 

value of ice storage 428 

of valve area 435 

velocity of brine 420 

water-cooling system 448 

Dexter system of refrigeration : n 

Diagram of cycle , . 66 

Dickinson 16, 258, 308 

Diffuser 167 

Dimensions of boilers 365 

compressors l 358, 360, 361 

Dimensions of engines 362 

generators 368 

motors 369 

producers 367 

turbo-generators 363 

Direct-expansion system : 5, 27, 245 

Displacement 70 

Distilled water 79 

Distilling apparatus 280 

, cost of 357 

Distribution of air 246 

Door, heat leakage 416 

construction 208 

Drinking water, cooling 331 

computations 335 

for hotels 338 

Dry bulb thermometers 50 

compression 68 

Drying air ' 3IO 

Duct, size of 248 

Dump, ice 290 

Dust preventing 222 

Dynamic pressure 250 

E 

Efficiency apparatus 347 

220 

, candling 220 



INDEX 461 

PAGE 

Eggs, cracking 221 

, temperatures of storage 222 

, weight . m 220 

Elbows 143 

Electric generators, cost of 350 

motors '. 115 

welding 140 

Elevator 238 

Engines, cost of 349 

, data 349 

, dimensions of 362 

, steam 115 

Equivalent speed 252 

volume 252 

Ethyl alcohol 105 

. Evaporating surface, effect of varying 306 

Evaporation, heat of 2 

Evaporator, refrigeration by 26 

, design of 283, 302, 307, 430 

Excavation costs 244 

Exchanger 34, 137 

Expander 66 

Expansion coils 31 

, storage of ammonia in 1 23 

for freezing 306 

joint 262 

valve 31, 289 

F 

Fan blowers, cost of and dimensions 352, 353 

data 251 

, size and power 422 

Fermenting tank 241 

tub 315 

Filter 276, 286 

size required 431 

Fish 225 

Flange union 141 

Flooded system ". 288 

Floor construction 207 

insulation 204 

costs 345 

Fore cooler 284 

Freezing by evaporation .' 37 

, coils for 306 

, tanks 303 

, time of 304 



462 INDEX 

PAGE 

Freezing tank 2 73, 288, 303 

, size 425 

Frick Co ; 2 ? 

machine ' ' 28, 122, 123, 124, 275 

Friction effect 44 

loss 249 

Fruit 227 

Fuels 348 

Furs 229 

Fusion, heat of .... 2, 215, 308 

G 

Gauge board : 29 

Gas Engine "S 

, cost of 35 

, data 35 

Gayley 319 

Generator 32, 134 

dimensions 368 

George 258 

Gobert system 329 

Goods, heat from 416 

Gorrie 21 

Grapes 228 

Grease separator 285 

H 

Hall, J. & E 26 

Hampson 340 

Hangers 146 

Hart cooling tower 171 

Haslam & Co 26 

Haynes 38 

Head cushion 109 

Headers 273 



Heads. 



117 



, false 

, spherical , 121 

Heat content S9 

-entropy diagram 61 

for breweries .317 

from door leakage 416 

goods 4I 6 

men " 4I 6 

loss from pipe , 334 

in cold storage 243 

Per year 408 



INDEX 463 

Heat of air leakage 213 

complete absorption 81 

partial absorption 81 

complete dilution 81 

fusion 2 , 215, 308 

lights.. . . 214 

machines 214 

persons ... 213 

solution 3 

of salt I4 

vaporization 2 

transfer I g >2 

through walls !go 

transmission ] 84 

Helmets 1 7g 

Hoofnagle 38 

Hoists 290 

Horse-power to drive 47 

Hotel air cooling 322 

boxes 238 

Hydraulic radius 249 

Hydrometer, correction for 295 

Hygrometer 50 

I 

Ice, amount of refrigeration 310 

and salt mixture 223 

, artificial 5 

, manufactured . . 5 

, can 289 

cold storage 241 

cream data ... .... 382 

cream freezer 326 

consumption, curve of . . 308 

, cooling by 3 

, cost of storage 309 

, delivery data 380 

, distribution 310 

, dump 200 

, heat of fusion 308 

, latent heat of fusion 41 

making 265 

, absorption system 297 

, passenger car 382 

plant, Frick 275 

, York 270 

saw 279 



464 INDEX 

PAGE 

Ice storage amount and economy 428 

plant data 3 IQ 

room 276 

tank insulation 208 

Inclined coordinates 62 

Incomplete expansion 48 

effect 48 

Indicator cards 41 

, from vapor machines 64 

, use of 113 

valve 29 

Indirect system 246 

Injecting liquid, effect of . . . 119 

Insulation 190, 201 

, amount of 244 

, cost of 345, 346 

, experimental determination of value 212 

values of K 211 

Insurance 206, 379 

Interchanger 33, 37 

Interest 379 

Interstate Commerce Rules 181 

J 

Jacket ; 126 

, effect of 1 1 2 

Jackson system of refrigeration Q 

Johns-Manville Co I3I 



21 



K 
Kirk ...... ! ......................................... ............ 

Kroechel machine .................................................... ! 2 g 

L 
Labor for plants .................................. ,-, 

Lagging ....................... ..................... ........... ' ' 1 1 2 

Land cost ......... 



112 

Latent heat ..................................... 2 

of fusion of ice ............................... 4I 

Laws, cold storage ......... 2I7 



machine test .................................... 4SI 

Lightfoot machine ........................ 

Lights, heat of ................... .' ' [][ [[ ' [[] ' _' ' _' [[ [' ..114 

, heat from ............................... ' 6 

Lillie evaporator .......................... ' ^ 



INDEX 465 

PAGE 

Linde 340 

Liquid air 340 

Liquid-air machines 34! 

Liquid line 58 

Liquid receiver 34! 

Lith 201 

Load factor 375 

Lorenz 3 29 

Loss of heat per year 408 

Low temperature by ice and salt 16 

Lubrication 121 

Lucke 80 

Lumber, costs 344 



M 

Machine, absorption * 31 

, Carbondale 36 

,York 35 

Allen dense air 19, 57 

compressed air 4 

, heat of 214 

, Lightfoot 19, 57 

, test of 400-405 

Machinery, co.sts 347 

Marine compressor 129 

Market 232 

Masonry costs 344 

McCray refrigerator 8 

Methyl alcohol .' 105 

chloride 31 , 105 

Meat 223 

Melons 229 

Men, heat from 416 

, required 373 

Milk 225 

Mill work, cost of 345 

Miscellaneous apparatus 357 

Motors, dimensions of 369 

, electric, cost of 350 

for driving compressors 115 

Moisture effect 5 

Mollier 80 

diagram 63 

Multiple effect 107 

, installation . 438 

, Voorhees 71 



466 INDEX 

N 

PAGE 

Nozzle design 1 7 & 

steam l6 7 

O 

Oil pump "9 

separator 3 1 

spray "7 

Onions 229 

Open air system 20 

Operating costs 37<S 377, 378, 379 

Operation of cylinders 123 

Oranges 228 

Osborne 16, 308 

Ott Jewell 297 

Oxy-acetylene welding 14 

Oysters ? 227 

P 

Packing house. . ._ 239 

, leather . 129 

Painting, cost of 345 

Partial pressure from aqua ammonia 80 

Partial absorption, heat of 81 

Partition, cost of , 345 

Passenger car ice 382 

Patten 38 

Peaches 228 

Pears 227 

Penny 169 

Performance of plants 370, 371, 372 

Perkins 4 

Perman 80 

Persons, heat from 213 

Pipe and fittings, cost of 354 

Pipe coefficients . . . v 255 

covering 200, 346 

data 355, 356 

for storage, cost of 357 

heat loss. . . m 

OO*r 

joints I4 2 

length, determination of 419 

lines, bell arid spigot 262 

line, brine 262 

line, size 257 

size at compressor 435 

.. 3o8 



INDEX 467 

PAGE 

Pipe, suction and discharge 119 

Piping 138 

arrangement 236 

for brine tanks 259 

for bunkers 256 

for rooms 256 

Piston 27, 109, 129 

, arctic 126 

design 435 

rod 121 

rod attachment 121 

rod design 435 

speed 434 

Planck 75 

Plant cost 376, 377, 378, 379 

Plate plant, size of 426 

Plate system 269, 276, 297 

Plumbing, cost of 345 

Plums 228 

Poetsch system for shaft sinking 328 

Point of boiling 2 

fusion 2 

melting 2 

Pond, cooling, design 178 

Poultry 224 

Power for deep well 300 

plants 370, 371, 372 

raw water ice 296 

to drive 106 

Precooling cars 264 

charges 382 

Pressure, effect of varying 307 

volume diagram 64 

Principle of refrigerating machines 5 

Problems, absorption machine 83 

, air machine 55 

, vapor machines 72 

, miscellaneous 407-4$* 

Producers, cost of 348 

dimensions 367 

Properties of ammonia 3 8 7~389 

of carbon dioxide 390-392 

of sulphur dioxide ' 393~395 

Pump, air lift 298 

, cost of 3Si 

data 3S 1 

, deep well 298 



468 INDEX 

PACK 

Pump, oil .................................................. ......... "9 

Pumping, cost of ..................................................... 4 2 9 

Purge valve .......................................................... 2 9 

R 

Radiation ........................................................... 182 

, required ................................................... 4 J 8 

Raw water .............................. ......... ................. 79, 269 

system ................................................... 290 

Reboiler .............................................. 274, 282, 284, 285 

, vacuum ..................................................... 283 

Receiver ...................................... ....................... . 161 

Receiver, cost of ..................................................... 353 

Rectifier ........................... ............... 33, 34i 136 

Reduced pressure ..................... ........................... 3 

Refrigerants ......................................................... 105 

Refrigerating capacity ................................................. 41 

effect .................................................... 46 

effect, vapor machines ..................................... 70 

effect from test ........................................... 449 

machine compression .............. . ....................... 26 

machines, general principle ............................... . . 5 

machines, diagram of cycle ................................. 66 

mediums ................................................. 31 

plants, cost of ................... ......................... 347 

Refrigeration ........................................................ 46 

applications of ........................................... 312' 

automatic ............................................... 263 

by chemical process ...................................... 40 

ice .................................................. 8 

evaporation ............. ............................. 26 

, central station ................ ............................ 260 

, determination of ...................................... 396, 398 

for brewery .............................. ................ 317 

creamery ............................................ 339 

dairy .................... ......................... ... 339 

plant ................................................ 428 

methods ................................................. 8 

Refrigerator ......................................................... g 

cars.... ........... ...................................... I3 

household, data . . . . ............................... ....... 384 

Relative humidity ................................ 50 



chart 



175 
Re P airs ............................................................. 379 

Return bends ..................... ; ............................ ^i, 144 

Return tubular boilers ............................. . . 363 

dimensions of ................................... 363 



INDEX 469 

PAGE 

Rietschel Igi 

Rinks 326 

Rink data 382 

Roadway, cost of 345 

Roelker 24 

Roofing, cost of 345 

Rooms, piping for 256 

Rooms, temperature of 244, 413 

Rugs 229 

Rules for safety 180 

S 

Safety devices 179 

head 29 

plate 129 

Salt, heat of solution 14 

Saturated ammonia, properties of 385-387 

Saturation line 58 

Scale separator 31 

Separator 33, 34, 119, 159 

. c st of 353 

, oil 31 

scale 31 

Setting box 312 

Shaft sinking 328 

Ship cold storage 240 

Single acting compressor, advantage of 113 

Skimmer 283 

Solution, heat of 3 

Space, cost of 409 

, storage, determination of 410 

Spangler 80 

Specific heat, determination 398 

of aqua ammonia 83 

brine 15, 258 

chocolate 313 

ice 16 

materials 215 

superheated steam 44 

vapors 64 

Speed, equivalent 252 

Spider 109 

Spray nozzles 172 

Stahl 38 

Static pressure 250 

Steam for plants ' 371 

washer 300 



470 INDEX 



Storage, cost of 2I5> 37S 

tank 31,287 

unit for 2I S 

Strainer ' j> 

Strawberries 228 

Stuffing box 27,112,117,121,126 

Suction side 29 

valve 28 

Sulphur dioxide 3i, >$ 

machine J 3 Z 

properties of 39i"393 

Supplies, cost of 357, 374 

Superheat, degrees of 6 3 

Sweet water cooler 2 4* 

Switchboard, cost of 35 

T 

Taxes 379 

Tees J 43 

Temperature at points on cycle J 9 

-entropy diagram 57 

mean difference l &5 

of freezing for brine 2 58 

ice and salt mixtures I 4 

rooms , 244, 4i3 

range, effect of 7i 79, 106 

Testing coils I2 4 

Test of apparatus 395 

cooling tower 46 

machines .400-405 

Tests 395 

Thermit welding 138 

Thermodynamics of refrigeration 41 

Thermometer comparison 395 

correction 397 

, use of 169 

Thomas spray nozzle 172 

Thompson-Joule effect , 34 

Throttle valve ... 32 

Tilting table 279 

Time of freezing 304 

storage 215 

Tobacco 229 

Tomatoes 229 

Tripler 340 

Triumph ice machine 127 

Tub, fermenting 315 



INDEX 471 

PACK 

Turbines, cost of 349 

data 349 

Turbo-generators, dimensions : 363 

Twining 4 

Two cylinders, use of 113 

U 

Ulrich 297 

Unions 141 

Unit for storage 215 

V 

Values of K 187 

Valves 1 2 1 , 148 

, cylinder 117 

, hurricane 125 

, indicator 29 

, manipulation of 123 

, mushroom 18 

, purge ... 29 

, sizes 435 

.slide 18 

, Triumph Co 127 

Vaporization, heat of 2 

under reduced pressure 3 

Vapor machine 57 

pressure 51 

pension 51 

Vegetables. 229 

Velocity of air 248 

pressure 250 

Ventilating air cooling 322 

Vogt Co 134 

Volume equivalent 252 

Volumetric efficiency 70, 434 

Voorhees 71, 107, 438 

W 

Wall coefficient, determination of 408 

constants 192 

for cold storage 243 

heat loss 413 

Warehouse construction 231 

data 383 

Water, best quantity of 440 

, cooling system design 448 

, cost of 374 



472 INDEX 

PAGE 

Water, distilled 79 

, distilled, amount required 300 

, effect of large quantities in air S3 

for condensing 432 

for cooling 374 

for ice making 298 

jacket 29 

jacket, value of 29 

per pound of aqua ammonia 81 

, raw 79 

storage tank 273 

tank insulation 337 

tube boiler, dimensions 365 

Weak liquor cooler 137 

Welding 138 

Westinghouse 39 

Westinghouse Le Blanc machine 167 

Wet and dry bulb hygrometer 1 74 

Wet bulb thermometer 50 

Wet compression 68 

White-wash 222 

Wood insulation 202 

Work of compression 43 

, air machine 20 

expansion 43 

with friction 44 

Y 

York ice plant 270 

machine 36, no, in 



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