The general situation is common on screw units, basically because of the large amount of liquid refrigerant (dissolved in the chilled oil) entering the compressor from the suction port.
The reason for causing liquid absorption is generally that the liquid refrigerant in the evaporator is "supply exceeds demand", and the heat transfer efficiency is low and cannot be effectively vaporized. Usually, the throttling device automatically turns off when the induction superheat is too small to reduce the flow of refrigerant into the evaporator, but sometimes it still does not work. For example, a large amount of oil film in the evaporator causes the heat exchange efficiency to drop.
The liquid refrigerant quickly flashes after entering the compressor, and absorbs heat at the same time, which causes the exhaust gas temperature to be too low and the exhaust superheat degree to be low. The low exhaust superheat degree will lead to the oil separation efficiency of the screw unit, and then a large amount of oil enters the refrigerant. Cycle into the evaporator. Especially for full-liquid evaporators, the oil in the evaporator cannot be effectively returned to the compressor through the oil return system, which leads to a vicious cycle.
Chiller: / Deng's
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