In the food industry, one of the essential aspects of food preservation is cold and, consequently, refrigeration systems. One of the most used systems for this task is forced air cooling.

Forced air tunnel

The use of rapid cooling tunnels is very common in food preservation, especially fruits and vegetables as they are the most perishable. This system allows for reducing quality losses.

The operation of this type of system consists of assembling the products in two blocks, with a canvas that covers the above. A fan draws out the hot air and makes the cold air pass through the products, in the middle of the two blocks.

It must be taken into account that the corridor that is left between the two blocks is neither excessively wide nor excessively narrow. If the space is too small, the products placed on the bottom will cool more difficult and slower. On the contrary, if the space is very large, the products will cool properly but the chamber space will not be optimized.

 

Advantages

The forced air tunnel offers a series of advantages:

  • The main advantage is the cooling speed. The period of time that the product remains at elevated temperatures is decreased. This minimizes spoilage.
  • Provides shorter periods for cooling, which allows rotation and therefore more efficient use of the facilities.
  • Rear lower thermal load for stock cameras or picking areas.
  • If a suitable packaging is chosen, it allows homogeneous cooling of the products without wetting them or subjecting them to excessive handling.
  • They are more energy-efficient than cameras without ventilation or cold rooms, which translates into energy savings.
  • If you have a chamber without ventilation, it can be transformed into a forced-air chamber with a relatively small investment in fans.

 

Choice of packaging

For this cooling system to function properly, it is important to use the proper gasket. They must be packages that allow the airflow to reach the product.

Normally, plastic or wooden boxes with openings are used. For the air to pass correctly into the interior of these, it is important to take into account some characteristics when choosing their design:

  • Openings must be of adequate size and shape to avoid being blocked when stacked.
  • Take into account the shape of the product so that they do not block the openings.
  • Make sure there are openings on all sides of the box so that air can enter and exit easily.

 

Selection and types of fans

The choice of fans will be made based on the airflow required and the pressure drop.

The two types of fans most used in forced air tunnels are Axial Flow fans and Radial fans (Medium and High Pressure Available). The former is the most used when high pressures or high speeds are not needed. Radial fans will be used when high pressures are required.

The fans can be fixed or mobile. The fixed fans will be placed next to the evaporators, at a height that allows them to reach the entire chamber. The mobile fans will be able to change places, choosing the optimal place for their correct operation and adapting to space.