Experimental investigation of the heating performance of refrigerant injection heat pump with a single-cylinder inverter-driven rotary compressor

Applying the refrigerant injection technology to air-source heat pump had been proved to be an effective access to acquire a better performance in the cold regions. In this paper, the test-bed of R410A single-cylinder rotary compressor vapor injection (SCRCVI) system with flash tank was built and measured by changing the compressor frequency f and injection pressure Pinj under various ambient temperatures. The experimental results indicated that the effect of refrigerant injection became stronger as the ambient temperature decreased. So the SCRCVI showed a superior heating performance at lower ambient temperature, and the conventional single-stage vapor compression (CSVC) system would exhibit higher COPh, while the ambient temperature was beyond the critical value. Compared with the CSVC system, the Qh and COPh were improved by 9.1 ~ 29.5 and 5.35 ~ 7.89%, respectively, under the ambient temperature Tod = − 10 °C. The injection pressure ratio Rp under different operating conditions was varied in the range between 0.2 and 0.22. Specifically, the trend in variation of Rp was reliably used to optimize the refrigerant injection system design and the control strategy.