Reduction of Oil Discharge for Rolling Piston Compressor Using CO_2 Refrigerant

摘要

In this paper, two approaches are presented to decrease the oil discharge ratio from the CO_2 rolling piston compressor. The first approach is a numerical analysis on the oil inflow into the compression chamber. Optimizing the radial sealing line of the rolling piston and the vane groove sealing line decrease the oil discharge ratio from compression chamber to the high-pressure shell. The second approach is a numerical analysis on the mixing flow of CO_2 refrigerant and oil in the high-pressure shell. The numerical analysis revealed that there are circling flows of CO_2 refrigerant with oil mist in the high-pressure shell and that circling flows are greatly related to the oil discharge ratio from the CO_2 rolling piston compressor. According to the above-mentioned analysis, optimized dimensions of the piston and vane can be determined, and a plate to prevent circling flows of CO_2 refrigerant and a cover to separate the oil from circling flows is designed. The decrease of the oil discharge ratio from the CO_2 compressor is confirmed by the experiment. As a result, a compact highly efficient CO_2 rolling piston compressor with oil discharge ratio less than 0.1 wt% has been successfully developed.