The reason for the frost on the compressor air inlet is here!

The reason for the frost on the compressor air inlet is here!
Frost on the air inlet of the cold storage compressor is a very common phenomenon in the refrigeration system. Under normal circumstances, no system problems will be formed immediately, and the subtle and ordinary frost does not need to be treated, but it will improve or change with some cold storage working conditions Increase the frost phenomenon.

If the frost phenomenon is more serious, then first need to understand the cause of frost. 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 of the same volume. The root cause of this situation is that the refrigerant flowing through the evaporator cannot fully absorb its expansion to the predetermined pressure and temperature value. The required heat, the temperature, pressure and volume of the return air are relatively low, and there are two reasons that can cause this problem:

1.The evaporator cannot absorb heat normally, or the cold generated by the evaporator cannot be taken away. The appearance is that the temperature and pressure of the return liquid are normal or slightly lower, and the frost gradually starts from the air return port of the compressor toward the evaporator. , And finally there was low pressure.

2.Due to the low amount of refrigerant, the low evaporation pressure of the evaporator leads to a low evaporation temperature, and it will gradually cause the evaporator to form a heat insulation layer and transfer the expansion point to the compressor return air to cause frost on the compressor return air. If the amount of fluorine is normal or excessive, and excessive condensation heat transfer occurs at the same time, resulting in low pressure at high pressure, then the refrigerant at the front end of the throttle valve under the same volume will reflect low pressure and high quality. At the initial throttle valve opening, the mass of refrigerant liquid flowing through the throttle valve will be more than normal, and the heat required from the evaporator will be absorbed too much. If the corresponding heat cannot be absorbed from the evaporator, it will cause the compressor to return The tracheal temperature is low. At the same time, because the pressure at the front end of the throttle valve is low, the pressure at the rear end of the throttle valve will also be low.
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4.If the expansion valve used in the cold storage installation system (detects the return air pipe temperature and pressure, the pipe temperature decreases and the opening decreases, the pressure decreases and the opening increases) compared to the normal state, the opening will not be adjusted much, then the low pressure will be maintained Condition until the compressor return air frost. This seems to be a lack of fluoride (high pressure, low pressure, and low pressure). The low temperature of the airway leads to frost.
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7.Finally, remind you that if the outlet of the evaporator freezes and the superheat of the return air is reduced, it is possible that there is too much refrigerant! Because one of the inevitable conditions for the evaporator to freeze is that the evaporation temperature must be below 0 degrees, and just how much refrigerant will cause the evaporation temperature to rise!