The working flow is as follows: the compressor compresses the low-pressure refrigerant flowing back and turns it into high-temperature and high-pressure gas to be discharged. The refrigerant gas with high temperature and high pressure flows through the copper tube wound outside the water tank, and the heat is conducted into the water tank through the copper tube. The cooled refrigerant becomes liquid under the continuous action of pressure and enters the evaporator after passing through the expansion valve. Because of the sudden drop of evaporator pressure, liquid refrigerant quickly evaporates into gas and absorbs a lot of heat. At the same time, under the action of the fan, a large amount of air flows through the outer surface of the evaporator, and the energy in the air is absorbed by the evaporator, and the air temperature drops rapidly and becomes cold air. Then the refrigerant that has absorbed certain energy flows back to the compressor and enters the next cycle.