Spiral freezers are effective and efficient cooling devices widely used in the food industry. These devices extend the shelf life of foods by enabling rapid freezing and preserve quality. The success of spiral freezers depends not only on their operation at low temperatures but also on ensuring proper humidity control. As NKT - Academy, in this article we will discuss why humidity control is important in spiral freezers and the factors that need to be ensured using dehumidifiers.
Spiral freezers have a multi-layer conveyor system. The freezer conveyor system is in contact with cooled air while transporting products up or down along a spiral (helix) path. Energy efficiency and sustainability in production are design prerequisites in these devices, which prioritize continuity and have large-scale product processing capacity.
Ensuring the correct humidity level by dehumidifiers during the freezing of foods plays a critical role in preserving product quality. High humidity levels cause ice crystal formation on products and damage to the cell structure during freezing, leading to loss of taste, texture, and nutritional value in foods. Additionally, it causes the internal evaporators inside the spiral freezer to enter frequent defrost cycles, increasing the operating cost of the process. Proper humidity control minimizes undesirable effects during the freezing process, preserving quality and process sustainability.
If dehumidifiers are not preferred in spiral freezer tunnels, high humidity levels can extend the process duration and reduce production speed. The operating temperature of many spiral freezers is at -40°C/-50°C dry bulb temperature level. Therefore, dehumidifier selection must be determined by considering all process details and performing detailed engineering calculations.
First, the entry conditions of the product must be determined. Information such as the dry bulb temperature and relative humidity of the space where the product enters, conveyor speed, whether products are packaged or unpackaged, moisture load from the product, and product entry/exit opening dimensions should be clarified before proceeding to the design phase. After determining the basic load factors of the dehumidifier to be integrated into the system, moisture load calculations should be performed.
At this stage, sending air at a dew point temperature approaching or lower than the dry bulb temperature of the indoor environment is important for extending the defrost duration and avoiding time/energy losses in production. By preventing icing on evaporators, the evaporators will remain dry and take longer to freeze. This results in increased uninterrupted production times by extending the period between two defrosts, and interruptions caused by malfunctions of moving parts in the indoor environment are minimized.
For spiral freezers properly conditioned with dehumidifiers, net work efficiency will increase thanks to improved cooling system efficiency, especially during summer months. Thus, the problem of reduced cooling capacity after a few days of operation will be eliminated, and consistent, high-quality products at the correct temperature will be achieved every day of the year.
Precise dew point sensors should be used to monitor humidity levels in spiral freezers. These sensors continuously measure the humidity level of the environment and automatically adjust the humidity control system when necessary. The airflow and insulation system of the low dew point dry air sent into the spiral freezer by the dehumidifier plays an important role in effectively controlling humidity. The airflow inside the freezer ensures homogeneous distribution of the dry air produced by the dehumidifier.
In cases where only infiltration load is encountered when products are packaged, low dew point dry air is blown onto the conveyor line through air blades at product entry openings to prevent outside moisture from penetrating inside. For the dry air produced by the dehumidifier to have a low dew point, the air taken from the outside environment is first cooled to 5°C or 7°C. The moisture in the air is removed inside the specially configured dehumidifier with insulation and sealing infrastructure designed to operate at low temperatures, and then delivered to the environment through ventilation ducts.
The dehumidifier must monitor the humidity level based on data from humidity sensors and send air at the appropriate pressure into the freezer in synchronization with the freezer operating parameters. This way, the humidity level in the indoor environment will remain stable and the dryness level will be continuously maintained.
Spiral freezers are effective cooling devices that play an important role in the food industry. Using silica gel rotor industrial dehumidifiers to preserve product quality, increase efficiency, and achieve energy savings is of critical importance in spiral freezer processes. To ensure correct humidity levels, capacity calculations within engineering discipline, humidity sensors, airflow and insulation systems, automatic control systems, and regular maintenance and cleaning measures should be implemented.
At NKT - Humidity Control Technologies, our expert engineering team offers the most suitable industrial dehumidifier solutions to our customers, providing energy-efficient, high-performance solution recommendations with our dehumidifier integrations in spiral freezers (spiral freezer, spiral tunnel).