64 MANAGEMENT OF DAIRY PLANTS 



The ice should be packed as already described, and may be 

 covered with prairie hay. 



Estimating Ice Storage. — In building for ice storage, it 

 is necessary to determine the space required which, in turn, is 

 dependent on the amount of ice likely to be needed during the 

 year. For these estimates there are more or less definite methods 

 of calculation. 



I. Amount of Ice Required. — In determining the amount of 

 ice to store, we should consider the loss of ice due to melting in 

 the ice house, the loss of ice in the refrigerator due to conduction 

 of heat through walls, floor, ceiling, etc., the amount of ice 

 required for chilling the particular products kept in the refriger- 

 ator, and the amount of ice used in the factory for various 

 purposes. In the problems that follow, it is supposed that ice 

 will need to be used for refrigeration only about 6 months in the 

 year, on the average. 



A. Loss from Shrinkage in Stored Ice. — In an ice-storage 

 house without artificial refrigeration, Siebel » estimated the 

 shrinkage from January to July to be i/io pound of ice every 

 24 hours for every square foot of wall surface; or, in round num- 

 bers, from 6 to 10 per cent of the ice stored during the 6 months 

 mentioned. In the average creamery ice-storage house, the 

 shrinking is usually estimated to be nearer 20 per cent; and this 

 latter rate is the factor used in the following calculations. 



B. Loss from Imperfect Insulation of Refrigerator. — (See 

 also the general formula, p. 62.) In refrigerators constructed 

 in accor ance with Table I (p. 63), the average loss in refrigera- 

 tion per day is 3 B. T. U. for each square foot, for each degree 

 of difference in temperature between the outside of the refriger- 

 ator an its inside. This average of 3 B. T. U. may reasonably 

 be considered as the unit of loss in 24 hours from the average 

 creamery refrigerator. Consider that, in a refrigerator 10 feet 

 square by 8 feet high, the temperature within the refrigerator 

 is 40° F. and that outside of the refrigerator is 70° F. — a fair 

 average for the 6 months. Then area of walls, floor, and ceiling 

 is equal to 520 square feet. 



' Siebel's Compend. of Mechanical Refrigeration and Engineering, 1911, p. 207. 



