Analyze the problem of refrigerant charging in high and low temperature test chamber compressors

The compressor is the heart of the high and low temperature test chamber refrigeration system. How much should it be added when the refrigerant needs to be added after the high and low temperature test chamber is used? What are the problems?

1. Q: If the refrigerant is filled too much, will the exhaust temperature be too high?

A: Too much charge will cause too much refrigerant in the condenser (or reservoir), which will reduce the cooling space, resulting in an increase in the condensing pressure. The increase in the condensing pressure will increase the flow through the throttling device. The evaporation pressure increases, so that the evaporation temperature also rises, causing the suction temperature to rise, so that the exhaust gas temperature also rises.

2. Q: As the refrigerant charge increases, the evaporation pressure also increases. Why? If the charge is low, the refrigerant vaporizes prematurely in the evaporator, but the gas and liquid pressures are the same. , but the temperature is different. In other words, as the amount of charging is only the problem of gasification, so does the pressure remain the same?

Answer: The evaporation pressure is determined by the amount of liquid supplied from the evaporator, the gasification speed of the liquid refrigerant, and the suction capacity of the compressor. If the evaporator supplies too much liquid, there are many refrigerants entering the evaporator, and there are many refrigerants vaporized at the same time, and the gasification amount is larger than the suction amount of the compressor, then the evaporation pressure naturally rises. The gasification rate is also related to the heat transfer condition, and the external heat exchange amount is larger (the larger the flow rate of the heat exchange medium, the higher the temperature, the greater the temperature difference between the refrigerant and the refrigerant). The boiling of the liquid refrigerant in the evaporator is more intense. The faster the gasification rate.