Heating performance comparison of R410A and its substitutions in air-to-water heat pumps with vapor injection

R410A has been widely applied in air-to-water heat pumps for space heating, but its phase-out process is accelerated due to the high GWP. This paper investigates the heating performances of low GWP HFO mixtures (R452B and R447B) as substitutions in a sub-cooler vapor injection cycle. The results illustrate that the capacities of R452B and R447B systems are lower by 0.7-5% and 6-15% in the measured conditions, respectively. The attenuation with the ambient temperature of R452B is slower than that of R410A, while R447B is faster. The COP improvements of R452B are 4-9% and 1.4-2.4% with and without vapor injection, respectively. The COP increases of R447B are 3-12% and 0.4-3.8% with and without vapor injection, respectively. In view of injection characteristics, the optimal injection pressure ratios of R452B and R447B are slightly higher. Synthetically R452B and R447B perform more excellent in the high outlet water temperature conditions and R452B is also suitable for low ambient temperatures. (C) 2018 Published by Elsevier Ltd.