① Compression refrigerator. Depending on the function of the compressor, the pressure of the refrigerant is increased to realize the refrigeration cycle. According to the type of refrigerant, it can be divided into vapor compression refrigerator (based on hydraulic evaporation refrigeration, the refrigerant will have periodic gas-liquid phase change) and gas compression refrigerator (based on high-pressure gas expansion refrigeration, the refrigerant is always in gas state), The vapor compression refrigerator is the most widely used modern refrigerator. ② Absorption refrigerator. Depending on the function of absorber generator group (thermochemical compressor), the refrigeration cycle can be divided into ammonia absorption type, lithium bromide absorption type and absorption diffusion type. ③ Steam jet refrigerator. The refrigeration cycle is completed by the action of steam ejector (jet compressor). ④ Semiconductor cooler. The thermal electric effect of semiconductor is used to produce cooling capacity.

The main performance indexes of the refrigerator include working temperature (evaporation temperature and condensation temperature for vapor compression refrigerator, temperature of cooled object and temperature of cooling medium for gas compression refrigerator and semiconductor refrigerator), refrigerating capacity (heat removed from cooled object by refrigerator per unit time), power or heat consumption and refrigeration coefficient (the index to measure the economy of compression refrigerator refers to the cooling capacity obtained by consuming unit work) and thermodynamic coefficient (the index to measure the economy of absorption and steam injection refrigerator refers to the cooling capacity obtained by consuming unit heat), etc.