17- 



The technology change has required increased cooling capacity for pull 

 down, which Is reflected In larger evaporators and bigger air handling systems. 

 The very first refrigerated rooms relied upon gravity refrigeration and contained 

 no supplemental air circulating equipment. By 1938, forced air blower units 

 delivered 18 air changes per hour and added approximately 198 watts of heat 

 per 1,000 bushels of stored fruit. Current centrifugal blower units have a 28 

 air-change -per-hour capacity. Direct throw propeller fans on modern 

 evaporators deliver 90 air changes per hour. The present hardware associated 

 with both types of systems adds approximately 375 watts of heat per 1,000 

 bushels of fruit. The heat added by the fan motors is now 2 to 3 times greater 

 than the heat of respiration of the fruit (130-180 W/1,000 bushels). 



The energy budget for a modern New York State CA storage is shown in 

 Figure 1. These data are for a 120,000 bushel plant equipped with flooded 

 ammonia refrigeration. The daily electrical requirements for cortpressors and 

 evaporator fans are shown along with the total for the refrigeration system. 



2500 



2000 - 



1500 



1000 



500 - 



• 40 Hp Conprcssor 



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7S Hp Compressor 



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OCT 



NOV 



occ 



JAN 



rcB 



APR 



MAT 



Fig. 1. Daily energy consumptions in a 120,000 bushel CA storage, where fans 

 were operated continuously. 



The "measured total" includes the relatively small amount of electricity used by 

 water pumps and condenser fans--a quantity which averages approximately 6% of 

 compressor use. The "metered total" is the daily average electrical use 

 calculated from monthly power company bills. Hot water heating, office space 

 heat, and the electricity used by CA burners and scrubbers are included in the 

 "metered total." 



