Document zQqGZb4VgVJXJ9qd86rkV3y6z

HEATINC VENTILATING AIR CONDITIONING GUIDE 1943 Summary: Component of Load Normal ^Transmission" ^ Radia"0n Transmission........... ,,.... ......... Solar Radiation Through Glass Outside Air ................. ................................. .......................................... .......... Liehts,,....... ................................................................... Total (Sensible and Latent Heat Gain) Btu per Hour 21,413 5,993 18,965 14,410 21,550 14,335 96,666 Latent Heat: Outside air 6.03 lb water per hour: Occupants 9.90 lb water per hour. 15.93 lb water per hour. 15.93 X ftfg = 15.93 X 1062.7 = 16,929 Btu per hour. Condition Line: The condition line for this application may .be determined from Equation 25 in Chapter 1 by taking the ratio of 96,666 -s- 15.93 = 6070 Btu per pound water. In this case, it crosses the saturation curve at a temperature for which the enthalpy h< and the humidity ratio 1P8 satisfy the equation, 31.40. -- As 0.01115 - Ws = 6070. A trial-by-error computation gives a quick solution of 57.4 F, which can also be deter mined graphically on a Mollier chart. This is the apparatus dew-point as explained in Chapters 1 and 21. Refrigeration Load: Assuming 100 per cent saturation efficiency for the air conditioning apparatus, operation at the apparatus dew-point is possible. The thermodynamic properties involved in calculating the refrigeration required are: Inside Air l..................... ....... 80.0.......... h..........:.......... ........ 31.40........ W.......................... 0.01115... After Cooling After Separating .........57 4.......................... 57.4 . ...:.....24.678..:.................. .24.65 0.01115.................. 0.01004 The refrigeration required is 31.4 -- 24.678 = 6.722 Btu per pound dry air. The total outside and recirculated dry air to be circulated through the air conditioning apparatus is 96,666 -I- (31.40 -- 24.65) = 14,321 lb per hour. Hence, the total refrigeration required or the cooling load is 14,321 X 6.722 = 96,265 Btu per hour, or 96,265 12,000 (Btu extracted per hour per ton of refrigeration) = 8.02 tons. The energy removed with the water eliminated is 14,321 X (24.678 -- 24.65) = 401 Btu per hour. This plus the refrigeration, accounts for the total removal of 96,265 .+ 401 = 96,666 Btu per hour as required. 164 Chapter 8 COMBUSTION AND FUELS Principles of Combustion, Classification of Coals, Firing Methods for Coals, Firing Methods for Coke, Dustless Treat ment of Coal, Classification of Oils, Combustion of Oil, Classi fication of Gas, Combustion of Gas THE data given in the first part of this chapter are of general appli cation to the various fuels used in domestic heating which are coal, coke, oil and gas. The choice of fuel is a question of dependability, cleanliness, fuel availability, economy, operating requirements and control. FUNDAMENTAL PRINCIPLES OF COMBUSTION Combustion may be defined as the chemical combination of a substance with oxygen with a resultant evolution of heat. The rate of combustion depends partly upon the specific rate of reaction of the combustible substance with oxygen and partly upon the rate at which oxygen is supplied and the surrounding conditions as they define the temperature. Complete combustion is obtained when all of the combustible elements in the fuel are oxidized with all of the oxygen with which they can combine. All of the oxygen supplied may not be utilized. Perfect combustion is defined as the result of supplying the required amount of oxygen for combination with all of, the combustible elements of the fuel and utilizing all of the oxygen so supplied. The oxygen" required for the process of combustion is obtained from air which is a mechanical mixture of oxygen, nitrogen and small amounts of carbon dioxide, water vapor and inert gases. These inert gases are generally included with the nitrogen, and for engineering purposes the values given herewith may be used. Bt Volume Per Cbnt 20.9 79.1 Bt Weight Per Cent 23.15 76.85 The combination of oxygen with the combustible elements and com pounds of a fuel is in accordance with fixed laws. In the case of perfect combustion the reactions and resultant combinations are shown in Table 1. The most important condition governing the process- of combustion is temperature. It is necessary to bring a combustible substance to its 165