The core problem of compressor oper
Matters needing attention when choosing evaporator for chiller
The evaporator is one of the four major components of the refrigeration system, and it is the ultimate manifestation of the cooling effect and efficiency. The evaporator is generally designed and equipped by the chiller manufacturer, and the user does not need to choose. However, in order to better maintain the refrigeration system and ensure its efficient operation, the following points should be noted:
1. The influence of liquid level on evaporation temperature.
Due to the influence of the height of the refrigerant liquid column of the chiller, the evaporation temperature at the bottom of the flooded evaporator is higher than the evaporation temperature of the liquid surface. The evaporation temperature of different refrigerants at different liquid levels is affected differently by the height of the static liquid. Regardless of the refrigerant, the lower the evaporation temperature of the liquid surface, the greater the influence of the hydrostatic height on the evaporation temperature. Therefore, only when the evaporation pressure is high, the influence of the hydrostatic height on the evaporation temperature can be ignored. When the evaporation temperature is low, it cannot be ignored. In other words, it becomes uneconomical to use a flooded evaporator at this time.
2. The possibility of freezing of the refrigerant.
If the evaporating temperature is lower than the freezing temperature of the refrigerant, the refrigerant may freeze. In the last process of the refrigerant, the temperature of the refrigerant is the lowest and the possibility of freezing is the greatest. When water is used as the refrigerant, theoretically, the temperature of the inner wall of the tube can be as low as 0°C. However, for safety reasons, the temperature of the inner wall of the pipe at the outlet end of the last process is usually kept above 0.5°C. In the case of brine as the refrigerant, according to the same principle, the temperature of the inner wall of the tube should be higher than the freezing temperature of the refrigerant by more than 1°C.
Third, the pressure loss of the water-cooled refrigerant in the evaporator.
When the refrigerant flows through the evaporator, the pressure loss is caused, which will inevitably make the pressure p2 of the refrigerant at the outlet of the evaporator lower than the pressure p1 at the inlet, thereby reducing the suction pressure of the compressor, resulting in a decline in the refrigeration capacity. According to different models, the choice of evaporator is different. For example, box-type chillers use water tank coil-type evaporators; open-type chillers and screw-type chillers use shell-and-tube evaporators; Acid-base chiller can choose titanium tube evaporator or stainless steel plate exchanger. There are many options for a chiller, and of course, it can be customized according to user needs.
