the heat capacity curves, over 100 per cent air supply, the assump-
tion being made that the total heat released is absorbed in raising
the temperature of the products of combustion. This curve has
a point of flexure at A on the curve of the heat capacity of the
products of combustion formed with 100 per cent or theoretical
With this line as a base the points for similar curves may be
located by setting off with a pair of dividers the additional heat
capacities added by the preheating of the gas and the air supply
to any temperature. These heat capacities are given in Table 4
and are plotted on the chart. The dividers may be set from the
air or gas heat capacity curves on the charts and measuring the
quantity of heat added at the temperature of preheat, and this
distance added to the base line A to fix a point upon a curve
showing the effect of preheat. Care should be used in stepping
these distances off to set the dividers parallel with B.t.u. or
The writer frequently prefers to sum up the preheat points
analytically, as shown, and use reference letters to connect the
corresponding values shown.
PEODUCEE GAS No. 3, CLEAN COLD GAS. TAE RETTTENED TO PEODTTCER
Liscum, A. C. Ford Motor, Co., Power, Aug. 31, 1920
Theoretical Air Supply
(1) (2) (3)
Products of Combustion
H2 16.60X 58.2 = CH4 5.50X195.2 = CO 27.10X 68.2 = CO2 3 90 ...
966 1074 1848
8.30 11.00 13.55
33.20 44.00 54.20
5.50 27.10 3.90
N2 46.30 .....
H2O 0.60 .....