2876S -- Design and Application of Variable Volume Ratio Screw Compressor PDF

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.