Principle: the gas must pass through a long pipe (usually coiled into a solenoid), so as to let the heat dissipate into the surrounding air. Heat conducting metals such as copper are often used to transport steam. In order to improve the efficiency of condenser, heat sink is often attached to the pipe to accelerate the heat dissipation. The heat sink is a flat plate made of good heat conducting metal. In general, this kind of condenser uses fans to force air through the fins and take away the tropics. The function of compressor is to compress the steam with lower pressure into the steam with higher pressure, so as to reduce the volume of steam and increase the pressure.

The compressor sucks in the working medium steam with lower pressure from the evaporator, and sends it to the condenser after the pressure rises. The liquid with higher pressure is condensed in the condenser. After being throttled by the throttle valve, it becomes the liquid with lower pressure, and then it is sent to the evaporator, where it absorbs heat and evaporates to become the steam with lower pressure, thus completing the refrigeration cycle.

In the refrigeration system, the evaporator, condenser, compressor and throttle valve are the four essential parts of the refrigeration system, in which the evaporator is the equipment to deliver the cooling capacity. The refrigerant absorbs the heat of the cooled object in it to realize refrigeration. The compressor is the heart, which takes in, compresses and transports refrigerant vapor. The condenser is a device to release heat, which transfers the heat absorbed by the evaporator to the cooling medium together with the heat converted by the compressor work. The throttle valve can throttle and depressurize the refrigerant, control and regulate the amount of refrigerant liquid flowing into the evaporator at the same time, and divide the system into high pressure side and low pressure side. In the actual refrigeration system, in addition to the above four parts, there are often some auxiliary equipment, such as solenoid valve, distributor, dryer, collector, fusible plug, pressure controller and other components, which are set to improve the economy, reliability and safety of operation. After the liquid refrigerant absorbs the heat of the cooled object in the evaporator, it vaporizes into low-temperature and low-pressure steam, is sucked in by the compressor, compressed into high-pressure and high-temperature steam, and then it is discharged into the condenser. In the condenser, it releases heat to the cooling medium (water or air), condenses into high-pressure liquid, throttles into low-pressure and low-temperature refrigerant through the throttle valve, and enters the evaporator again to absorb heat and vaporize, so as to achieve circulation Purpose of refrigeration. In this way, the refrigerant in the system through evaporation, compression, condensation, throttling four basic processes to complete a refrigeration cycle