Assessment of the influence of gap wall mobility factor at calculation of leakage in working section of a scroll compressor. Part 1

Abstract

The scroll type compressor is widely used in the medium capacity segment of refrigeration and air
conditioning technology including heat pumps. Today there is an active process of changing from
hydrofluorocarbons to natural refrigerants with low global warming potential. CO2, with its low critical
point and correspondingly high operating pressures, is gaining in importance. For operation with new
refrigerants, the scroll compressor has to be adapted to take account of all its design features, the
most important of which are the clearances in the machine's flow area. It has to be considered that
the thermodynamic properties of carbon dioxide, different from hydrofluorocarbons, have a significant
influence on the volume and energy values of the compressor. In this case relevance consists in increase
of accuracy of compressor losses calculation and prediction of refrigeration machine characteristics. As
the basic volumetric losses in the scroll compressor are leakages of working substance in its working
part, and the process of flow of medium is unsteady, their quantitative component causes interest.
The purpose of this work is to clarify the physical basis of the leakage process in the radial clearance
and the degree of influence of various factors on it. Such analysis gives further opportunity to refine
the methodology of calculation of leakages of compressed medium, taking into account the mobility
factor of gap walls. It will raise accuracy of the received results which can serve as a base to prognosis
of optimum characteristics of the compressor, due to their approximation and will allow to optimize
designing of refrigerating machines at the chosen modes of work.