RErEIGERATION 6$ 



The amount of ice melted due to heat that is being conducted 

 through walls, floor, and ceihng during a period of 6 months or 

 1 80 days is equal to 



520X3(70-40) ^ ^g^ ^ ^^^^ ^^^^ 



284,000 



C. Ice Required for Chilling Products Stored. — Different 

 products take up a different amount of refrigeration for each de- 

 gree that temperature is reduced. This depends on the specific 

 heat 1 of the product. The specific heat of butter at 60° F. is 

 .53 B. T. U.; 2 that of cream at the same temperature is .84. 

 Suppose the refrigerator is used for butter only, and that 600 

 pounds daily has to be reduced in temperature from 60° to 40° F. 

 Then 



Daily heat removed from 600 pounds of butter = 



600 X .53 X (60 - 40) = 6,360 B. T. U. 



If the butter is packed in tubs or boxes, it will furthermore be 

 necessary to reduce the temperature of these containers to the 

 same extent. Suppose ash tubs of 60 pounds capacity are used, 

 that each tub weighs 10 pounds, and that the specific heat of 

 wet ash wood be .4.^ Then 



Daily heat removed from 10 tubs = 100 X 4 B. T. U. X 20 

 = 800' B. T. U. 



Daily ice required for cooling butter and tubs = — 



142 



= 50.42 pounds. 



Total ice required for 6 months = 50.42 X 180 = 9,075.6 



J 9,075.6 



pounds; or, ^— = 4.54 tons. 



2.000 



' The specific heat of any substance is the amount of heat, expressed in B. T. U., 

 which will be absorbed by i pound of that substance in raising its temperature 

 T° F.; conversely, it is the amount of heat, in B. T. U., which will be given off by 

 I pound of that substance in lowering its temperature 1° F. 



' Research Bui. 14, Iowa Agr. Expt. Sta., 1913 



^ Bulletin no, U. S. Forestry Bureau, gives the specific heat of dry white ash as 

 .327. 



