The evaporator is an indispensable and important component in the refrigeration system. As the most commonly used evaporator in cold storage, the air cooler is properly selected, which directly affects the cooling efficiency
Influence of Evaporator Frosting on Refrigeration System
When the refrigeration system of the cold storage is in normal operation, the surface temperature of the evaporator is much lower than the dew point temperature of the air, and the moisture in the air will precipitate and condense on the tube wall. If the tube wall temperature is lower than 0°C, the dew will condense into frost. Frosting is also a result of normal operation of the refrigeration system, so a small amount of frosting is allowed on the surface of the evaporator.
Because the thermal conductivity of frost is too small, it is one percent, or even one percent, of metal, so the frost layer forms a large thermal resistance. Especially when the frost layer is thick, it is like heat preservation, so that the cold in the evaporator is not easy to dissipate, which affects the cooling effect of the evaporator, and finally makes the cold storage unable to reach the required temperature. At the same time, the evaporation of the refrigerant in the evaporator should also be weakened, and the incompletely evaporated refrigerant may be sucked into the compressor to cause liquid accumulation accidents. Therefore, we must try to remove the frost layer, otherwise the double layer will become thicker and the cooling effect will be worse and worse.
How to choose a suitable evaporator?
As we all know, depending on the required ambient temperature, the air cooler will adopt different fin pitches. The most commonly used air cooler in the refrigeration industry has a fin spacing of 4mm, 4.5mm, 6~8mm, 10mm, 12mm, and front and rear variable pitch. The fin spacing of the air cooler is small, this type of air cooler is suitable for use in high temperature environments, the lower the temperature of the cold storage。the greater the spacing requirements of the cooling fan fins. If an inappropriate air cooler is selected, the frosting speed of the fins is too fast, which will soon block the air outlet channel of the air cooler, which will cause the temperature in the cold storage to cool down slowly. Once the compression mechanism cannot be fully utilized, it will eventually cause The electricity consumption of refrigeration systems is constantly increasing.
How to quickly select a suitable evaporator for different use environments？
High-temperature cold storage (storage temperature: 0°C~20°C): for example, workshop air-conditioning, cool storage, cold storage hallway, fresh-keeping storage, air-conditioning storage, ripening storage, etc., generally choose a cooling fan with a fin spacing of 4mm-4.5mm
Low-temperature cold storage (storage temperature: -16°C--25°C): For example, low-temperature refrigeration and low-temperature logistics warehouses should choose cooling fans with a fin spacing of 6mm-8mm
Quick-freezing warehouse (storage temperature: -25°C-35°C): generally choose a cooling fan with a fin spacing of 10mm~12mm. If the quick-frozen cold storage requires high humidity of the goods, a cooling fan with variable fin spacing should be selected, and the fin spacing on the air inlet side can reach 16mm.
However, for some cold storages with special purposes, the fin spacing of the cooling fan cannot be selected simply according to the temperature in the cold storage. Above ℃, because of the high incoming temperature, fast cooling speed, and high humidity of the cargo, it is not suitable to use a cooling fan with a fin spacing of 4mm or 4.5mm, and a cooling fan with a fin spacing of 8mm-10mm must be used. There are also fresh-keeping warehouses similar to those for storing fruits and vegetables such as garlic and apples. The suitable storage temperature is generally -2°C. For fresh-keeping or air-conditioned warehouses with a storage temperature lower than 0°C, it is also necessary to choose a fin spacing of not less than 8mm. The cooling fan can avoid the air duct blockage caused by the rapid lightning of the cooling fan and the increase of power consumption.
Post time: Nov-24-2022