r 



BN-7917 



Figure 11 . --Interior of truck trailer equipped with 

 sidewall strips which keep load from fitting too 

 tightly against sidewalls, thereby permitting side- 

 wall air circulation. The side strips shown here 

 would have been more effective if they had extended 

 higher. 



Test 36 was the only test in the group of 8 shipments of controlled- 

 atmosphere storage apples made in a trailer equipped with an ice bunker and 

 a blower. The test trailer had only \\ inches of insulation. Under the 

 best conditions, and even if the trailer had been equipped with wall strips, 

 water ice refrigeration could not have been expected to provide temperatures 

 much lower than those shown in table 3 with the ambient temperature at close 

 to 80° F. However, the accelerated circulation of air from the lengthwise 

 air channels through the load resulted in the maintenance of temperatures in 

 this trailer which compared favorably with the averages on earlier tests that 

 moved under mechanical refrigeration but had inadequate circulation because 

 of the blocking of the air channels by the loading method. 



Another important consideration in connection with air circulation and 

 maintenance of desirable fruit temperatures is the combined total size of the 

 openings in the grooved floors of the trailers compared with the total area of 

 the blower outlet on the refrigeration unit. For most of the test trailers, 

 the total area of a cross section of all the grooves was approximately 42 square 

 inches, whereas the blower outlet area was 240 square inches. Where the area 

 of the grooves represents such a small ratio to the blower outlet area, it would 

 have been more efficient to use floor racks in addition to the extruded aluminum 

 floor than to depend entirely on the grooved floor for circulation under the load, 



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