Refrigeration working medium (ie refrigerant) absorbs the heat of the cooled object in the evaporator and vaporizes into steam. The compressor continuously extracts the generated steam from the evaporator and compresses it. The compressed high-temperature and high-pressure steam is After being sent to the condenser, it releases heat to the cooling medium (such as water, air, etc.) to condense into a high-pressure liquid, enters the evaporator after being depressurized by the throttling mechanism, vaporizes again, absorbs the heat of the cooled object, and so circulates repeatedly. During heating, the refrigerant changes the flow direction of the refrigerant through the four-way valve. The flow direction of the refrigerant is opposite to that during cooling. The refrigerant first passes through the evaporator, then returns to the condenser, and finally returns to the compressor.