Performance Evaluation of Low-Global Warming Potential Refrigerants R513A and R516A as Alternatives to R134a in Simultaneous Heating and Cooling Systems

Abstract The shift to low-global warming potential (GWP) refrigerants is critical to mitigating climate change and improving energy efficiency. This study evaluates the performance of low-GWP refrigerants R513A and R516A as alternatives to R134a in water-to-water heat pump systems designed for simultaneous heating and cooling. Using experimental data and a validated mathematical model, the study evaluates the coefficients of performance (COPs), heat transfer rates, and refrigerant mass flowrates under medium- and high-temperature scenarios. The medium-temperature conditions consisted of evaporator inlet temperatures ranging from 0 °C to 5 °C and condenser inlet temperatures of 35–40 °C, while the high-temperature conditions had evaporator inlet temperatures of 10–15 °C and condenser inlet temperatures of 50–55 °C. The results demonstrate that while R134a exhibits marginally higher COP in the heating mode, R513A and R516A show competitive performance, with R516A excelling in high-temperature scenarios. This study highlights the potential of R513A and R516A for sustainable heating, ventilation, and air-conditioning applications, contributing to global efforts in reducing greenhouse gas emissions. In addition, experimental data were used to propose a correlation to calculate the heat transfer coefficient during evaporation and condensation in brazed plate heat exchangers for the fluids R513A, R516A, and R134a.