. Commercial cooling of fruits and vegetables. Fruit; Fruit; Vegetables. the produce. Wider stacks, which simplify han- dling and reduce the floor area occupied by air channels, are therefore possible without delaying the cooling of downstream produce, although static pressure required to move the air increases rapidly as stack-width is increased. Shipping containers are commonly stacked three-wide on pallets and placed so that air flows through the stacks across the pallet width. Ar- rangements that provide longer air paths through the containers save space but also re- quire higher air press
. Commercial cooling of fruits and vegetables. Fruit; Fruit; Vegetables. the produce. Wider stacks, which simplify han- dling and reduce the floor area occupied by air channels, are therefore possible without delaying the cooling of downstream produce, although static pressure required to move the air increases rapidly as stack-width is increased. Shipping containers are commonly stacked three-wide on pallets and placed so that air flows through the stacks across the pallet width. Ar- rangements that provide longer air paths through the containers save space but also re- quire higher air pressure and result in more uneven cooling. Shorter air paths allow faster cooling and less air pressure but require more floor space (fig. 25). One plant in Arizona stacks grape boxes two-wide on pallets which are then conveyed through an air-cooled tunnel; the air- flow is large enough to cool the fruit from 90°F to 40°F in 1 hour. In one Mexican plant, tomato boxes are moved by hand trucks and placed in single stacks against air slots in the wall of air- return plenums for forced-air cooling. Stacks 1-foot wide permit flow of a large vol- ume of air for fast cooling with low static pres- sure (fig. 25). However, 60 per cent of the floor area is occupied by air channels, which means that this system is practical only if that much area can be economically given to the channels. Such a short air path has been utilized for cer- tain conveyor-type coolers, coolers using vertical air flow, or coolers where containers are placed against air vents in a wall. Most forced-air coolers utilize stacks 3 or 4 feet wide; reasonably good cooling rates are attained with moderate static pressures, and these widths make economic use of floor space. Floor space may be more efficiently used with stacks 6 feet or more in width, but static pressure require- ments are then usually unreasonably high for efficient cooling of downstream produce. Wide stacks should be used only for some special rea- son,
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