COLD STORAGE FOR APPLES AND PEARS 



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DUCT USED FOR DELIVERY 



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DUCT USED FOR RETURN 



Figuee 14. — Diagram of delivery and return ducts that may be used interchange- 

 ably with a reverse air system. Deflector vanes are used to equalize the quan- 

 tity of air delivered from the varisized duct openings. These openings are 

 larger as the distance from the fan room increases, to equalize the flow of 

 returning air. Their number is adjusted to the length of the duct. 



If the dampers are arranged to operate automatically they require 

 a minimum of attention. To take full advantage of air reversals, 

 ample volume and good distribution are necessary. If such distribu- 

 tion and volume are provided, periodic reversal of the air will result 

 in a minimum difference in fruit temperature throughout the room. 

 The method is particularly adapted to rooms in which air below the 

 freezing point of the 

 fruit is used for the 

 rapid removal of heat 

 in precooling. Revers- 

 ing the air periodi- 

 cally lessens the dan- 

 ger of freezing the 

 fruit near the dis- 

 charge openings. 



Air traveling along 

 a delivery duct with 

 plain openings along 

 the side or bottom 

 tends to move past the 

 first openings, and the 

 openings farthest 

 from the fan tend to 

 discharge more air 

 than those nearest. In 

 a return duct the re- 

 verse is true ; more air 

 tends to enter the 

 openings nearer the 

 fan. These effects may 

 be compensated by 

 adjusting the size of 

 the openings. In a 

 delivery duct the 

 openings nearest the 



Figuee 15. — View from below of a duct opening near 

 the fan room in a reverse air system. The opening 

 is narrow, and an internal deflector vane, or scoop, 

 is used to divert the proper quantity of air to this 

 part of the room. 



fan may be made largest and those at the far end smallest. In a 

 return duct, openings may be small near the fan and larger as the 

 distance from the fan increases. If the same duct is to be used alter- 

 nately for delivery and return, however, this gradation in size of 

 openings will obviously not be satisfactory. When the duct is used 



