3 temperatures are measured in the thawing chamber and are used as switching parameters : the chamber temperature, the surface temperature and the core temperature of the product
In the first step the chamber temperature is increased to the maximum (preset) value by feeding in ambient air with high humidity (preferably fresh steam).
This is maintained until the product has reached the maximum specified preset surface temperature.
From this moment on the process is controlled by the surface temperature. As soon as it falls below the preset value, because the colder temperature from inside the product is discharged to the outside, the heater receives a renewed start signal.
In this way, only the energy required to achieve optimum thawing is applied to the products. This avoids overheating of the outside of the product.
By establishing a very high humidity, optimum temperature exchange between the product and ambient air is possible.
This process continues until the core of the product has reached the required defrosting temperature. Then the unit is switched off – an information signal indicates the end of the process.
Use of this process controlled technology can significantly reduce product weight loss. Compared to conventional thawing in a water tank with weight losses between 6 – 8%, this method not only offers more uniform product treatment but also reduces the weight loss to approx. 1.5 %.
By the appropriately designed cooling evaporator which is integrated into the central air conditioner , this plant can – on demand by microprocessor – after completion of the thawing process furthermore used as cold storage room (0 ° C). This makes the removal of the thawed goods for the customer far more flexible.
The values required for the process are stored in a microprocessor as a program; the necessary control is then calculated and controlled automatically.
The addition of a UVC degerminating unit to the central air conditioner unit is especially useful for thawing chambers. It not only reduces germ infestation in all circulated room air considerably, but also prevents the growth and infestation with yeast, mould and other bacteria on the fins of the cooling evaporator. This lengthens the cleaning intervals considerably