Scroll Optimization

Abstract

The scroll compressor consists of two plane spiral/helix running inside each other, traditionally both scrolls are the same circle involute with constant wall thickness.
When the moving scroll follows a circular orbit the chambers moves inwards and the air or fluid trapped in the chambers is compressed. In the standard circle involute scroll compressor the volume of the compression chambers grows linearly when we move outwards and the compression rate of such a compressor is sufficient for air condition, but not for freezers or refrigerators. One could try to increase the compression rate by having more chambers, but that would increase the leakage too.

The task was to investigate how a change in the basic geometry of the scrolls and the orbit influence the compressor performance and efficiency, and then try to optimize the design.

We have not done any optimization, but we believe we have found a sound foundation for the optimization process. We can represent the geometry of the problem in a way which leads to closed expressions for all the geometric quantities which are interesting for the scroll design. We have also analyzed the leakage between the compression chambers, and using a compressible lubrication model we have determined an expression which, appart from one integration, leads to a closed expression for the leakage.