The refrigerant conducts heat energy in the refrigeration system to realize the refrigeration cycle: the refrigerant condenses into a liquid after passing through the condenser, passes through the throttling action of the expansion valve, evaporates and absorbs heat in the evaporator to achieve refrigeration, and then flows back to compression Machine-then flow into the condenser. The refrigerant temperature sensor is to test the temperature of the refrigerant circulation pipe. The tested temperature deviates from the actual refrigerant temperature, and the throttling device improves the accuracy of the refrigerant temperature monitoring. The temperature monitoring device detects the throttling mechanism to the evaporator. The refrigerant temperature difference, and then the refrigeration system can directly control the evaporator refrigerant flow rate and evaporator outlet superheat.