The liquid level of the condenser of the low temperature refrigerator at minus 35℃ will be higher. When the refrigerant level cannot be accurately observed or further judgment is required, the following methods can be used:
① When the compressor is running, turn off the cooling water of the condenser. If the temperature of the liquid pipe rises sharply and the high pressure pressure also rises sharply; after stopping the compressor, if the high pressure pressure drops quickly, it means that the condenser is stored Some liquid refrigerants are very small.
②Stop using the thermal expansion valve, open and properly adjust the opening of the manual expansion valve. If the system can work back to normal, it means that the thermal expansion valve is not adjusted properly. Otherwise, it indicates that there is insufficient refrigerant in the system. When the refrigerant in the system is insufficient, leak detection should be carried out to eliminate the leakage and add refrigerant.
LNEYA briefly analyzes the phenomenon of excessive refrigerant in the low-temperature refrigerator system at minus 35℃:
When there is too much refrigerant in the system, the liquid level in the condenser is higher, the condensation heat exchange area is reduced, and the condensation pressure increases, that is, the pressure before the expansion valve increases, and the amount of refrigerant flowing into the evaporator increases. The evaporator cannot completely evaporate, so the compressor sucks in wet vapor, and the cylinder hair is cold or even frosted, which may cause “liquid hammer”. At the same time, the evaporation pressure will be higher.
A similar phenomenon can occur when the expansion valve is opened too large, which can be distinguished by the following methods:
1. Observe the refrigerant level in the condenser. When there is too much refrigerant in the low temperature refrigerator system at minus 35℃, the liquid level will be high; and when the expansion valve opening is too large, the liquid level will be low.
2. Close the thermal expansion valve, open and adjust the manual expansion valve. If the abnormal phenomenon can be eliminated, it means that the opening of the thermal expansion valve is too large, otherwise it means that there is too much refrigerant in the system. Too much refrigerant in the system is often caused by improper operation during filling. When this kind of failure occurs, the excess refrigerant should be discharged.
Through the analysis of several common typical failures above, it can be seen that each type of failure will have corresponding abnormal phenomena in different parts, and each abnormal phenomenon is often caused by multiple failures.