The performance of compressors is an important key in air-source heat pumps under different climatic conditions. The development of compressors is reviewed in this study. Previously

the compressor used in a room air conditioner was a piston compressor. With the emergence of rotary and scroll compressors

the efficiency of compressors has increased. Both rotary and scroll compressors have been developed to adapt to low ambient temperature. Simultaneously

the key technologies that affect the development of compressors are introduced. The compressor efficiency is improved by the improvement in the motor and compressor structures. The coefficient of performance (COP) and integrated part load value (IPLV(H)) have been improved using the techniques of variable compression ratio

enhanced vapor injection

and integrated-part load adjustment. The use of DC motors instead of AC motors can increase the motor efficiency and range of frequency adjustment of both compressors. By designing the scroll compressor using asymmetric swirl disks

noise and leakage can be reduced. The symmetrical arrangement of dual rotors can enhance the compressor capacity. Scroll compressors with exhaust valves can achieve variable compression ratios to a certain extent. Rotor compressors contain exhaust valves

which offer significant advantages in varying operating conditions. Both types of compressors can use the gas injection technology to achieve a high compression ratio of the heat pump at a low ambient temperature.