Refrigeration

3954

Refrigeration

urn available (cooling water temperature).
On subsequent heating of such a substance
it must also have the property of releasing
the refrigerant at a pressure high enough to
effect condensation at the temperature of the
cooling medium. Aside from the absorption
and liberation of the refrigerant the remaind-
er of the refrigerating cycle, involving the
condensation and expansion in refrigerating
coils after passing a regulating valve, is es-
sentially the same as used in the compres-
sion system. After expansion the gas is re-
absorbed in the substance and the cycle

is considered a necessity in the household.
Electric refrigerating units are of the com-
pression or machine type, and rapid progress
has been made in the adaptation of the ab-
sorption system to the smaller sized units
of gas machines. The simplification of the
apparatus, freedom from moving and wear-
ing parts, silent operation and availability
of low cost fuels are inherent advantages of
the absorption system. Ammonia is the prin-
cipal refrigerant and both liquid and solid
absorbents for ammonia are used in this
system. Cold storage is the art of preserving

HEAT EXCHANGER

VALVB
ABSOftER.

LIQUID HEAT CXCHAN6EP

Diagram of Ammonia Refrigerator.

repeated. The largest application of the ab-
sorption system consists of the use of am-
monia as a refrigerant and water as an ab-
sorbent substance. The second important
factor in refrigeration is the insulation, by
which heat is prevented from penetrating
the walls and entering the cold storeroom.
The insulating material must be light, porous,
containing minute air spaces, odorless, of
minimum capacity for moisture, vermin
proof, non-inflammable and elastic to pre-
vent settling. Until recent years the familiar
household ice box has been the principal
means of preserving food in the home. The
advent of mechanical refrigeration rather
than causing a decrease in the number of
ice users, has stimulated the industry and
today, more than ever before, refrigeration

articles of a perishable nature by keeping
them in chambers constantly maintained at
a low temperature. The refrigeration duty
in cold storage may be divided into the fol-
lowing classes from which the total may be
calculated, (i) Refrigeration to cool the
goods stored. (2) Refrigeration to absorb the
heat transmitted through the insulation. (3)
Refrigeration to offset ventilation losses. (4)
Refrigeration to absorb heat generated in
the room. It is not uncommon to have as
many as 100 different articles stored in a cold
storage house, only a few of which can be
considered. Eggs are among the most im-
portant products preserved by cold storage.
Butter is stored for periods of three to six
months. Cold storage of fruits is designed
to arrest the ripening process and to retard