The compressor is the "heart" of the refrigeration system, compressing the low-temperature and low-pressure refrigerant gas into a high-temperature and high-pressure refrigerant gas. Common compressors are: semi-hermetic piston compressor, scroll compressor, screw compressor, etc.

2. Air-cooled fin heat exchanger
Condenser function: to cool the superheated vapor of the refrigerant discharged from the compressor, and condense it into a refrigerant liquid, and the heat of the refrigerant in the condenser is discharged to the cooling medium.

Condenser classification: water-cooled condenser; air cooled condenser; cooler evaporators.

The advantages of water-cooled condensers are high heat transfer efficiency and compact structure. The disadvantage is that a cooling water system is required. The scale on the tube wall reduces the heat transfer effect and needs to be cleaned regularly.

The advantage of the air cooled condenser is that it does not require cooling water and is easy to use and install. The disadvantage is that the heat transfer coefficient is low, the volume and weight are relatively large, and the dust on the surface of the fins will deteriorate the heat transfer, which needs to be cleaned in time.
3. Shell and tube heat exchanger
Direct expansion shell and tube heat exchangers, where the refrigerant is in the tubes and the water flows in a shell with baffles. In cooling mode, it is an evaporator to provide chilled water; in heating mode, it is a water-cooled condenser, which provides hot water.

4. Four-way reversing valve, thermal expansion valve
The four-way valve can change the flow direction of the refrigerant, so as to achieve the purpose of switching the cooling/heating mode. It is mainly composed of pilot valve, main valve and solenoid coil. When working, the solenoid coil is switched on and off to control the switching of the pilot valve, and the slider slides through the pressure difference between the two ends of the main valve to realize the switching of cooling and heating modes.
The expansion valve can control the refrigerant flow. The expansion valve senses the change of the refrigerant superheat at the outlet of the evaporator through the temperature sensor to control the opening of the valve, and adjusts the refrigerant flow into the evaporator to make the flow and the heat load of the evaporator. match. In addition, the degree of superheat can be controlled, that is, to keep the heat transfer area of the evaporator fully utilized, and to prevent the occurrence of compressor flushing accidents.

5. Gas-liquid separator
By changing the suction flow direction and reducing the suction flow speed, the liquid droplets are separated, preventing the liquid from entering the compressor and causing liquid hammer.

6. Fan
The fan is to implement forced convection to reduce the temperature of the condenser and achieve the purpose of adjusting the air temperature.