Air freezing uses forced air to raise the coefficient of heat transmission. It is still the process of freezing most used for its flexibility. It can be practically used with all products. Air-freezing tunnels can be manual or automatic.
The manuals are simply small chambers with support devices that allow the passage of air through the product. The air circulates between the product and the evaporator in a closed circuit.
The coefficient of heat transmission is low (from 20 to 25 kcal / h.m2 ° C for common tunnels) and its increase by increasing air velocity becomes economically
unfeasible from certain values. For special tunnels, such as fluidization tunnels, the values are 50kcal / h.m2 ° C.
The automatic tunnels are in fact the automatic movement of the product, that take advantage of this characteristic to obtain better yields and allow their inclusion in automatic processing lines. Hence its great advantage.
