The evaporator is one of the main heat exchange equipment of the refrigeration system. In the evaporator, the throttled low-temperature and low-pressure liquid refrigerant boils in the evaporator, and the liquid is converted into vapor, which absorbs the heat of the cooled medium (such as water, salt water or air), and reduces the temperature of water, salt water or air, To achieve the purpose of cooling and cooling. The evaporator is a low-pressure device that produces and outputs cold energy in the refrigeration system.