The purpose of the spiral freezer is to quickly decrease product temperature prior to transporting or placing in storage. Product travels through the spiral freezer on a belt, with the time spent in the freezing process controlled by the belt speed. The enclosed area of the spiral freezer, or box, is maintained at a target temperature, with evaporator fans operating at a defined speed to maintain air flow across product while the evaporator coils remove heat from the space.
There are three key operating parameters for the spiral freezer: belt speed, temperature, and air flow. Target product temperatures at the outlet of the spiral freezer typically vary due to differing product geometry, weight, and ingredients. If a spiral freezer is operated at the highest fan speed and lowest temperature, some products may become over frozen, which can result in breakage and poor performance in end use. End use impacts can vary depending on the type of product, for example a raw yeast product not properly rising. For some facilities, the product mix is diverse so the required operating conditions for each product can vary significantly.