First, what are the common problems in general cold storage maintenance?

1. Cold storage due to poor insulation or sealing performance, resulting in large cold loss

2. The frost on the surface of the cold storage evaporator is too thick or the dust is too much, and the heat transfer effect decreases

3. Cold storage air cooler heat transfer area is not enough.

4. There is more air or frozen oil in the cold storage evaporator and the heat transfer effect decreases

5. The cold storage throttle valve is improperly adjusted or blocked; the refrigerant flow is too large or too small

6. The refrigeration in the cold storage system is insufficient and the refrigeration capacity is insufficient

7. The compressor efficiency is low; cooling capacity cannot meet the requirements of the cold storage load

Second, how to solve if there is problem with cold storage?

The cooling temperature of cold storage drops slowly, which is mostly caused by improper operation adjustment, among which the adjustment of expansion valve is the most critical.

The opening degree of expansion valve is small, the flow rate of refrigerant is less, and the pressure is low; The opening degree of expansion valve is large, the flow rate of refrigerant through is much, and the pressure is high. According to the thermal properties of refrigerant, the lower the pressure, the lower the corresponding temperature; The higher the pressure, the higher the temperature.

According to this law, if the outlet pressure of the expansion valve is too low, the corresponding evaporation pressure and temperature are too low. However, due to the reduction of the flow into the evaporator, the reduction of pressure, resulting in slow evaporation rate, unit volume (time) cooling capacity decline, refrigeration efficiency reduce. On the contrary, if the outlet pressure of the expansion valve is too high, the corresponding evaporation pressure and temperature are too high. The flow and pressure into the evaporator are increased, because of excess liquid evaporation, the moisture gas (or even liquid) is inhaled by the compressor, causing the wet stroke of the compressor (liquid strike), so that the compressor cannot work properly, resulting in a series of bad working conditions, and even damage the compressor.

The opening degree of expansion valve should be adjusted according to the cold storage temperature at that time, that is, under the pressure corresponding to the cold storage temperature.