制冷剂的压缩过程分两段进行避免了因压缩比增加而导致压缩机容积效率下降而引起的功率消耗增加，在相同的低温工况下双级压缩制冷循环中制冷系数cop及制冷量较单级压缩机均有所提高使运行更经济更可靠

The compression process of the refrigerant is carried out in two stages to oid the increase of the power consumption caused by the decrease of the volumetric efficiency of the compressor due to the increase of the compression ratio. In the same low temperature condition, the refrigeration coefficient cop and the cooling capacity in the two-stage compression refrigeration cycle are relatively simple. Grade compressors he been improved to make operation more economical and reliable