Performance investigation and optimization analysis for vapor injection rotary compressor oriented to circular end-plate injection port without check valve

Abstract Vapor refrigerant injection technique can effectively improve the performance and heating capacity of the rotary compressor heat pump systems in cold regions. However, due to the arrangement of the check valve at the injection port of the rotary compressor, the compressor manufacturing process needs to be improved to a large extent, which prevents the application of the vapor refrigerant injection technique. The manufacturing process of the vapor injection rotary compressor using a circular end-plate injection port without check valve is very simple. In order to avoid the backflow in the injection process and affect the performance of the compressor, the general expressions of the envelopes and the effective injection areas of the injection ports are developed based on an analytical geometry method in this paper. Meanwhile, a numerical model for predicting the performance of the vapor injection compressors is proposed. The effects of different operating conditions, different end of injection rotation angles, and different injection port radii on the upper and lower limits of injection pressure, injection ratio, and the system performance were analyzed. According to the prediction results, the optimal design scheme of the injection compressor using a circular end-plate injection port without check valve is proposed. The results indicate that at low ambient temperatures, the optimal design of the injection port structure has increased the heating capacity 12.1%-28.3% over the traditional compressor without injection, and COP also has been increased 1.6%-3.6%.