自20世纪50年代末以来，旋转螺杆压缩机已成功应用于工业制冷行业。然而，限制其应用的一个特点是它们是固定容积比压缩机。压缩机设计用于一个工作压缩比；如果以不同的比例使用，其效率将降低。开发了一种在螺杆压缩机运行过程中改变容积比的实用方法，并成功应用。螺杆压缩机设计的这一进步消除了与过度压缩或欠压缩相关的损失，并降低了能耗，尤其是在具有可变工作压力比的应用中，或在需要具有不易获得的体积比的压缩机的应用中。 引用:ASHRAE Transactions，1985年，第91卷，第1部分。伊利诺伊州芝加哥1A

Rotary screw compressors have been successfully applied in the industrial refrigeration industry since the late 1950s. However, one characteristic that has limited their application is that they are fixed-volume ratio compressors. A compressor is designed for one operating compression ratio; if applied at a different ratio, its efficiency will be reduced.A practical method for varying the volume ratio of a screw compressor during operation has been developed and successfully applied. This advance in screw compressor design eliminates the losses associated with over- or undercompression and provides for reduced energy consumption, particularly on applications with variable operating pressure ratios or on applications requiring a compressor with a volume ratio that is not readily available.