Piston-type compressors, when when the compression ratio is greater than 8~10, generally uses two-stage compression; as for the use of refrigerant R22 reciprocating compressor when evaporating temperature lower than-30 ° c up to the use of two-stage compression type; Air-cooled condensers using high speed punch punching, flanging II, copper tubes and fins mechanically expanding close, high heat exchange efficiency;