FARM STORAGES FOR APPLES 27 



Men working within the storage give off heat at the rate of 500 B. t. u. an hour. 

 This amount of heat is so small that ordinarily it need not be considered in es- 

 timating the refrigeration load. 



Electric lights and motors operating within storage rooms give off heat which 

 has to be absorbed by the refrigeration unit. Lights develop heat at the rate of 

 341 B. t. u. per 100 watts an hour. Since relatively few lights are used in an 

 apple storage and as they do not burn continuously, the heat from this .source 

 can also be neglected. A one h. p. electric motor generates about 3000 B. t. u. an 

 hour, or the equivalent of J^ ton of refrigeration. Motors on cooling units operate 

 continuously during the loading period, and hence it is necessary to allow an 

 additional refrigeration capacity of }i ton for each motor-horsepower used on 

 cooling units above that required to overcome heat leakage and to remove the 

 heat from the apples. 



A room 40'x42'xl0' has a volume of 16,800 cubic feet. Allowing IM cubic 

 feet per bushel, the capacity of the room is 6720 bushels. If the storage is filled in 

 ten days, the daily loading will be 672 bushels. It was determined that the 

 refrigeration load in cooling 1000 bushels of apples to 32° under the assumed 

 conditions is 6.7 tons. To cool 672 bushels would require .672X6.7, or 4.5 tons. 

 In like manner it would require .672X5.6 or 3.75 tons to cool the 672 bushels a 

 day to 45°. If we assume that a 2 h. p. motor is used on the cooling unit, an 

 additional K ton of refrigeration must be allowed to take care of the heat given 

 off by this motor. The total refrigeration capacity would then be as follows: 



Table 7. — Refrigeration Load, in Tons. 



32° 45° 



Heat leakage (40'X42'X10' building) 1.40 .85 



Cooling 672 bushels a day 4.50 3.75 



Heat from 2 h. p. motor 50 .50 



Total 6.40 5.10 



