Performance Measurement of R32 Vapor Injection Heat Pump System

As global warming has raised more critical concerns in recent years, refrigerants with high global warming potentials (GWP) are facing the challenges of being phased out. R410A, with a GWP of 2,088, has been widely used in residential air-conditioning and heat pump systems. A potential substitute for R410A is R32, which has a GWP of 675. This paper investigates the performance difference of R410A and R32 in a vapor-injected heat pump system. A drop-in test was performed using R32 in a heat pump system that was designed for R410A, for both cooling and heating conditions. Through experimentation, it was found that for a single-stage cycle without vapor injection, the capacity improvement of using R32 was between 3.4% and 9.7%, and the COP improvement was between 2.0% and 9.0%, as compared to an identical cycle using R410A. For the vapor injection mode, the capacity improvement of R32 was found to be 1.8% to 7.4%, and the COP improvement was found to be 1.2% to 5.7%. No improvement was found for extreme cooling and heating conditions. High compressor discharge temperature was observed at extreme cooling and heating conditions when using R32. The compressor performance was analyzed to better understand the performance difference between the two different refrigerants. It is concluded that R32 is an excellent alternative to replace R410A in terms of performance and can be further enhanced by component optimization.