COLD STORAGE FOR APPLES AND PEARS 35 



room. For this reason, a vapor barrier on this side of an insulated 

 wall may do more harm than good. 



BASEMENT FLOORS 



A vulnerable point in the insulation of most fruit cold storages is 

 the basement floor. Beneath a concrete floor, on account of dampness 

 and structural requirements, the insulation, if any, is frequently make- 

 shift. This is expensive, because ground heat prevails during the 

 winter after air temperatures above ground are low, and either exces- 

 sive refrigeration is used to take care of this leakage or the fruit in 

 the basement is kept at undesirably high temperatures. Usually both 

 conditions exist : even if refrigeration is supplied to maintain low air 

 temperatures in the upper part of the basement room, the temper- 

 ature of the fruit resting on the concrete floor will be kept somewhat 

 above optimum because of conduction from the ground through the 

 concrete. 



Durable insulation equivalent to 4 inches of cork is recommended 

 for basement floors. It is as desirable to provide a space beneath the 

 fruit as between the fruit and the outside walls. For this reason 

 the insulation of bottom floors, whether in the basement or above 

 ground, should be augmented with floor racks or false floors to permit 

 the circulation of cold air beneath the fruit. 



Calculating Refrigeration Requirements 



In calculating the refrigeration requirements of a cold-storage plant 

 all sources of heat have to be considered. Following is a typical 

 example. 



Example. — Calculate the capacity of refrigerating equipment for a cold-storage 

 plant 70X100 feet, having two floors with rooms 9 feet high, one of which is a 

 basement. The walls and roof are insulated with 12 inches of planer shavings 

 and the basement floor with 12 inches of pumice gravel. The average outside wall 

 temperature is estimated to be 65° F., the roof temperature 75°, and the ground 

 temperature 55°. It is desired to refrigerate 50,000 boxes of apples, 30,000 of 

 which are an early variety, like Delicious, to be picked and received over a period 

 of 10 days, the fruit to be cooled from 65° to 32° in not more than 7 days. 



Field Heat in Fruit 



33° (reduction) X0.9 (specific heat) =29.7 B. t. u per pound. 



29.7X50 lb. (box weight) X 3,000 boxes (per day) =4,455,000 B. t. u. per day. 



Heat of Respiration 



While cooling from 65° to 32° in 7 days, apples generate 21,000 B. t. u. per ton 



(estimated from table by D. H. Rose and others (20)). 

 3,000 boxes daily=75 tons. 

 75X21,000=1,575,000 B. t. u. per day. 



Building-Heat Leakage 



Basement : B - *■ »■ P er da v 



Floor: 7,000 sq. ft. X 1.25 B. t. u.X23° 201,250 



Walls: 2,920 sq. ft.XO.75 B. t. u.X23° 50,370 



Ground floor : 



Walls: 2,920 sq. ft. X 0.75 B. t. u.X33° 72,270 



Ceiling: 7,000 sq. ft.X0.75 B. t. u.x43° 235,750 



Total 559. 640 



