It includes air cooler, water separator and automatic liquid discharger. Evaporator is built in air cooler and refrigeration system is installed in evaporator. The refrigeration system includes compressor, condenser, compressor, condenser, evaporator and compressor, which constitute refrigerant pipeline circulation circuit. It is characterized by a stop valve on the pipeline between the outlet of compressor and the inlet of evaporator.The globe valve uses a solenoid globe valve and a temperature sensor connected to the solenoid globe valve is provided at the evaporator.