A novel single cylinder rotary compressor

which was increased a vapor injection hole near the discharge port

was adopted to improve the heating performance of a flash tank vapor injection air-source heat pump (FTHP) system at low ambient temperature. The effects of compressor frequency f and injection pressure pinj on system performances of a R410A FTHP system were measured and investigated systematically. The results showed that both heating capacity and power consuming of the FTHP system increased with increasing the compressor frequency and injection pressure. The FTHP system power consuming at fixed frequency increased linearly with increasing injection pressure. The increasing rate of FTHP system heating capacity declined as the frequency and injection pressure increased. Therefore

the heating COPh had a peak value at certain injection pressure when the frequency was low. After the peak point or at high frequency

the heating COPh decreased as the frequency and injection pressure increased. In the range of 800 kPa to 1200 kPa and 50 Hz to 80 Hz

the maximum improvement of the FTHP heating capacity

power consuming

and COPh were 27.55%

30.75% and 7.1%

respectively

compared to the single stage compression system. In order to make the FTHP system efficiently

the control strategy must be optimized to keep the system operated at the optimum injection pressure and frequency.