Troubleshooting of low valve temperature of screw chiller

Troubleshooting of low valve temperature of screw chiller

The outlet temperature of the expansion valve of the screw chiller reflects the evaporation temperature, which is a factor that affects the heat exchange. Generally, the difference between it and the outlet temperature of the refrigerant water is 5~6℃. When a low valve temperature failure occurs, the compressor will stop, and when the valve temperature rises, it will automatically resume operation with a protection value of -2°C. The reasons for the low valve temperature failure are as follows:

　　(1) A small amount of refrigerant leaks, which generally manifests as a low valve temperature failure rather than a low pressure failure. Insufficient refrigerant will evaporate at the outlet of the expansion valve, resulting in cooling, which is manifested as frosting at the outlet of the expansion valve, while the temperature of the suction port is higher (superheated steam) and the cooling capacity decreases and the temperature drops slowly.

　　(2) The expansion valve is blocked or the opening degree is too small, and the system is not clean. For example, the refrigerant pipeline is not cleaned after maintenance, and the refrigerant is impure or contains moisture.

(3) The refrigerant water flow is insufficient or the evaporator is blocked. Poor heat exchange results in low evaporating temperature and low suction temperature. The opening of the expansion valve is adjusted according to the suction temperature. If the temperature is low, the opening will be small. Low valve temperature failure.

　　 (4) False alarms caused by electrical faults, such as poor contact of the valve temperature line, causing the computer to display -5°C unchanged.