Forced-Air Cooling of Fruits, Vegetables, and Dairy

Forced-Air Cooling

Forced-air Cooling is the process of quickly removing heat from product by creating a pressure differential across the product. The Product, usually stacked on pallets, is oriented in rows and “sealed” to control the flow of cold air through the product, rather than around it. Forced-air Cooling is sometimes called blast cooling or blast chilling.

a forced-air cooling tunnel The old way

On a “tarped-tunnel”, the product is butted up against the fan plenum with rows of palletized product on either side. A tarp is laid across the top and back. When the fan is turned on, it pulls on the center section between the pallets. The room air is cooled with a refrigeration coil. As the fan creates a negative pressure zone between the pallets, the cold air (room air) on the outside of the pallets is “forced” to go through the pallets. Over time, the heat is removed through convection.

A forced-air cooling tunnel with the tarp onThere are several drawbacks to the traditional tarped-tunnel method. Tunnel setup takes several minutes, and each pallet or pair of pallets must be located manually and accurately to prevent gaps where air could bypass the pallet. Also, the room air is typically mixed with warmer air coming in through the doors, plus the large space required to have tunnels means more refrigeration is required to cool “unusable” or wasted space. And of course, once the cooling is finished, the tarp must be lifted and the pallets moved to cold storage.

The MACS Cooler way

Enter the MACS Cooler, the automated forced-air cooling system.

The MACS Cooler uses forced-air cooling, like the tarped-tunnel in the previous example, but with the efficiency dial cranked to 11. Pallets are set on the MACS Cooler’s infeed conveyors. Once a full load (6 pallets) has been staged, the door opens and the pallets are inserted automatically into the first precooling zone. As the pallets move from infeeds to Zone 1 they are packed tightly (again, automatically).

Once inside the cooling zone, the seals (MACS equivalent to the tarp) are inflated, pressing tightly against the product, creating the negative pressure zone. Powerful fans draw cold air through the pallets and chill the warm air that comes off of the product with refrigeration coils in the upper plenum. Because of the compact size of the cooling zone, there is no wasted space to cool.

Seals of a MACS precooler inflating against pallets of strawberriesAs the product advances from one cooling zone to the next, the seals extend and retract, and the air direction is reversed to produce even cooling, automatically.

An LED display notifies operators and drivers of how much time is left before the product moves to the next cooling zone. When the product has moved through all of the cooling zones, it moves on to the outfeed conveyors where it can be picked up and moved to cold storage or transport.A forklift unloads strawberry pallets from a MACS precooler

MACS Coolers are an excellent choice for precooling strawberries, raspberries, grapes, broccoli, bell peppers, cauliflower, dairy products and more. If you have a forced-air cooling need, request a quote and see if a MACS Cooler is right for you.