Introduction to the Relationship between Refrigerants and Cold Storage Temperatures

Refrigerant is a relatively important factor affecting the temperature of the cold storage. And the blockage of the throttle valve is an important factor affecting the flow rate of the refrigerant.

When the throttle valve is improperly adjusted or blocked, it will directly affect the flow rate of the refrigerant entering the evaporator. When the opening degree of the throttle valve in the cold storage is too large, the flow rate of the refrigerant is too large, and the evaporation pressure and evaporation temperature will also increase accordingly, and the temperature drop rate in the storage will slow down. At the same time, when the opening degree of the throttle valve is too small or blocked, the flow rate of the refrigerant will also decrease, and the refrigerating capacity of the system will also decrease, and the temperature drop rate in the storage will also slow down.
Generally, it can be judged whether the refrigerant flow rate of the throttle valve is appropriate by observing the evaporation pressure, the evaporation temperature and the frosting situation of the suction pipe. The main reasons for the blockage of the throttle valve are ice blockage and dirty blockage.
Ice blockage is due to the poor drying effect of the dryer. The refrigerant contains moisture. When it flows through the throttle valve, the temperature drops below 0 °C, and the moisture in the refrigerant freezes into ice and blocks the orifice of the throttle valve. Dirty blockage is due to the accumulation of more dirt on the inlet filter screen of the throttle valve, resulting in poor refrigerant circulation and blockage.
The amount of refrigerant in the system is insufficient and the refrigeration capacity is insufficient.

There are mainly two reasons for the insufficient refrigerant circulation volume. One is the insufficient refrigerant charge. At this time, it is only necessary to add a sufficient amount of refrigerant for the cold storage. The other reason is that there is a large amount of refrigerant leakage in the system. In this case, the leakage point should be found first, with the focus on checking the connections of pipes and valves.

After finding the leakage part and repairing it, a sufficient amount of refrigerant should be filled in.
The efficiency of the cold storage compressor is low, and the refrigerating capacity cannot meet the load requirements of the cold storage.
Due to long-term operation of the compressor, parts such as the cylinder liner and piston ring are severely worn, the fit clearance increases, the sealing performance will decrease accordingly, the gas transmission coefficient of the compressor will also decrease, and the refrigerating capacity will be reduced. When the refrigerating capacity is less than the heat load of the storage, it will cause the temperature in the storage to drop slowly. The refrigerating capacity of the compressor can be roughly judged by observing the suction and exhaust pressures of the compressor.

If the refrigerating capacity of the compressor decreases, the common method is to replace the cylinder liner and piston ring of the compressor. If it still does not work after replacement, other factors should be considered, and even the machine should be disassembled for overhaul to eliminate the fault factors.