Testing and characterisation of a scroll compressor with vapour injection using R454C as a drop in refrigerant in a water source heat pump.

Transition to low-global-warming-potential (GWP) refrigerants is a significant issue for reducing the environmental impact of heat pumps to comply with stringent regulations. This study evaluates the performance of a scroll compressor with vapor injection (VI) using R454C as a low GWP drop-in replacement for R407C in a water source heat pump. Key performance indicators, including isentropic and volumetric efficiency, heating capacity and COP, are investigated across a wide range of operating conditions. These include varying compressor speeds, superheats at both the main and economizer electronic expansion valves as well as condensation and evaporation temperatures. Results indicate that R454C achieves higher volumetric efficiency (+2 %) and mass flow rate (+11–13 %) compared to R407C but leads to a lower heating capacity by 13–14.8 % and a decreased COP by 6 % due to lower latent heat. Vapor injection boosts the heating capacity by up to 30 % while decreases discharge temperatures, especially at high pressure ratios, despite an 8 % reduction in isentropic efficiency. These findings underscore the potential of R454C as a low-GWP replacement in heat pumps and highlight the critical role of VI in enhancing system performance even at moderate temperature lifts.