Experimental comparisons on a gas engine heat pump using R134a and low-GWP refrigerant R152a

Gas engine heat pump (GEHP) is attracting increasing interests owing to the high heating efficiency. However, the refrigerants used in existing GEHPs present high global warming potential (GWP) values, facing the challenge to be phased out. In this work, the heating performances of a water-source GEHP using R134a and low-GWP refrigerant R152a were investigated and compared. The influences of engine speed and evaporator inlet temperature on the refrigerant operating parameters, heating performances, and compressor efficiencies were evaluated. The results indicated that the GEHP using R152a showed higher heating efficiencies, higher compressor efficiencies, lower discharge pressures, and lower natural gas consumption as compared to R134a. As the gas engine speed increases from 1200 rpm to 1600 rpm, the primary energy ratio, isentropic efficiency and volumetric efficiency using R152a have an improvement of 2.6–10.4%, 3.5–10.7% and 5.8–7.3%, respectively, compared to R134a. The comparisons of experimental results indicate that the GEHP can achieve higher heating performance by using low-GWP refrigerant R152a as the drop-in alternative for R134a.