At some extreme operating conditions, such as overloading, high pressure ratio etc., due to overheated motor and screws, it would occur to the screw compressor of the air-cooled screw air conditioning unit that the discharge pressure is too high. In order to limit the discharge temperature in an acceptable range, jet cooling is required for the motor and screws. Through comparing merits and demerits of jet cooling on the suction chamber (suction inlet) and on the medium pressure chamber (compressor screws) with lots of contrast tests and test analysis, this paper consequently figures out a method to precisely control the liquid jet volume by using the electrostatic expansion valve.%风冷螺杆热泵机组螺杆压缩机在某些恶劣工况下（如过负荷工况、高压缩比工况等）运行时，由于电机及螺杆压缩热过大，会引起排气温度偏高。为了控制排气温度在一个合理的范围内，可以对电机和螺杆进行喷液冷却。本文介绍了通过采用吸气腔（压缩机吸气口）喷液和中间腔（压缩机螺杆）喷液来降低排气温度的方法，并对两种方式进行对比实验，经过分析，找出了一种采用电子膨胀阀精确控制吸气腔喷液量的实用冷却方案。
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