LAUSR

Abstract In recent years, low-temperature air source heat pumps using vapor refrigerant injection technique, which can effectively improve the performance and heating capacity of the rotary compressor heat pump systems in cold regions, have become more and more widely used. The injection rotary compressor without a check valve in the injection path has a great manufacturing advantage compared to that with a check valve. Improper position of the injection port will cause serious backflow during compression, which will greatly affect the performance of the heat pump. In order to study and correct the backflow in the injection process of the compressor, this paper analyzes the refrigerant flow characteristics of the compressor with a circular injection port without a check valve based on experiments and computational fluid dynamics. Through the analysis of the cause of backflow, the optimal position of the injection port is proposed, which has effectively solved the problem of refrigerant backflow caused by the injection. In addition, the operating strategy is optimized based on the results of computational fluid dynamics. The simulation results indicate that at low ambient temperatures, the optimal design of the injection port structure has increased the heating capacity 21.75%–45.3% over the traditional compressor without injection, and the coefficient of performance for heating also has been increased by 3.06%–5.15%.