A common phenomenon in the refrigeration system is frosting at the air return of the compressor of the cold storage. Generally, there is no need to deal with slight frosting. If it is serious, it will be troublesome. There are several main reasons for frost:
1、 Frosting at the return port of the compressor in the cold storage
If the volume and pressure of the refrigerant of the same quality are changed, the temperature will behave differently. If the return air temperature of the compressor is low, it will generally show a low return air pressure and a high amount of refrigerant with the same volume. The root cause of this situation is that the refrigerant flowing through the evaporator cannot fully absorb itself and expand to a predetermined pressure. The amount of heat required for the temperature value.
2、 Less fluoride
Too little refrigerant will form low temperature in the evaporator, frosting of the evaporator, and because of the heat insulation layer formed on the surface of the evaporator, the heat exchange in this area is low, the expansion of the refrigerant will transfer to other areas, and the entire evaporation will gradually appear. When the compressor is frosted or icing, the entire evaporator forms a heat insulation layer, so the expansion will spread to the compressor return pipe and cause the compressor return air to frost.
3、 the cylinder head is frosted
The frost on the cylinder head is caused by a large amount of wet steam or refrigerant sucked into the compressor. The main reasons for this situation are: the opening of the thermal expansion valve is adjusted too large, the temperature sensing bulb is installed incorrectly or the fixing is loose, so that the temperature felt is too high, which makes the valve core open abnormally and the liquid supply solenoid valve leaks Or the expansion valve is not closed tightly during shutdown, and there is too much refrigerant in the system.
It can be cleaned, replaced the thermal expansion valve, re-wrapped the temperature sensor, leak detection, leak repair, and filled with refrigerant according to the situation.
The temperature sensor of the temperature relay is placed in the cold storage. When the temperature of the cold storage is higher than the upper limit of the set value, the contact of the temperature relay is turned on, the solenoid valve coil is energized, the valve opens, and the refrigerant enters the evaporator to cool down; At the lower limit of its setting value, the temperature relay contact opens, cuts off the solenoid valve coil current, the solenoid valve closes, and the refrigerant stops entering the evaporator, so that the storage temperature can be controlled within the required range.