Investigation of working fluid performance in a refrigeration cycle

With global warming and climate change, the world is experiencing a steady temperature rise. Hence the need for effective and efficient air conditioning,
cooling and refrigeration systems is higher than ever. One of the key elements influencing refrigeration system performance is the working fluid. From 2022, new refrigeration systems in the UK must not use refrigeration fluids with global warming potential (GWP) above 150. Widely used R134a, with GWP of 1430, is therefore being banned and the need for suitable replacement fluids, with equivalent or similar thermodynamic performance, is imminent. This paper looks into the potential of low GWP refrigerant fluids, and assesses their suitability to be utilised as replacement for historically used R134a. Operation of a refrigeration cycle based on R134a is comprehensively compared to selected low GWP fluids in different operating conditions. Low GWP fluids (R152a, R1234yf, R1234ze(E), R290, R600a) were carefully selected to include a broad range of thermophysical properties and cover several fluid categories. Compression work requirement, cooling capacity and the overall performance are evaluated in typical operating scenarios. We conclude that both R1234ze(E) and R1234yf are good alternatives. In particular, R1234yf outperformed R134a by requiring less compression work and achieving significantly higher COP based on the same cooling capacity.