COLD STORAGE FOR APPLES AND PEARS 



53 



mary air is forced through the space between boxes, and little space 

 is left between boxes and ceiling. In this case the natural convec- 

 tion from the ceiling down into the stacks is greatly reduced, but 

 the forced circulation among the boxes gives better cooling on 

 account of the higher air velocity. 



It will be seen that if natural convection is sacrificed by reducing 

 the ceiling space, it is important that forced circulation take its 

 place. Otherwise the effectiveness of cooling will be reduced instead 

 of increased. For this reason, if it is attempted to force air through 

 the box spaces by cutting down circulation over the fruit, great care 

 must be exercised in 

 arranging the boxes. 

 Uniform spacing be- 

 comes even more im- 

 portant, and air chan- 

 nels that will permit 

 diversion of air 

 around the stacks of 

 boxes must be avoided. 

 Precooling rooms in 

 which these conditions 

 are met provide much 

 faster cooling than 

 rooms in which nat- 

 ural convection is de- 

 pended upon for cool- 

 ing the interior of the 

 stacks. 



Control of the 

 Plant 



In a cold-storage 

 plant the relatively 

 large investment in 

 machinery and con- 

 struction can be justi- 

 fied only if it increases 

 the value of the fruit 

 stored. The value of 

 a plant in maintaining 

 this condition is 

 largely determined by the way it is operated. Even the best designed 

 plant with automatic equipment needs more or less continuous atten- 

 tion to insure the best results. 



Figure 22. — Packages stacked without spacing and 

 too close to the ceiling. This prevents uniform 

 distribution of refrigeration. 



CORE TEMPERATURE 



To make the best use of a plant it is important to know what tem- 

 peratures are being maintained. One or two thermometers for show- 

 ing aisle-air temperatures do not indicate the performance of a plant. 



