Comparative analysis of HFO-1234ze(E) and R-515B as low GWP alternatives to HFC-134a in moderately high temperature heat pumps
Abstract This study provides a theoretical comprehensive performance and environmental analysis of the hydrofluoroolefin HFO-1234ze(E) and the mixture R-515B as alternative low global warming potential (GWP) refrigerants to replace the hydrofluorocarbon HFC-134a in heat pumps. Single-stage cycle, including the use of internal heat exchanger (IHX) has been used as a reference configuration. The influence of an IHX has been simulated to present the benefits of this component in vapour compression systems for medium and moderately high temperature heating applications. HFO-1234ze(E) and R-515B provide around 25% lower heating capacity than HFC-134a due to a diminution of latent heat of vaporization and suction density. The heating capacity difference between HFO-1234ze(E) and R-515B becomes not greater than 2%. The heating coefficient of performance (COP) of the alternative low-GWP refrigerants is comparable to the reference HFC-134a in the conditions proposed. The environmental analysis illustrates that HFO-1234ze(E) and R-515B can reduce down to 18% and 15%, respectively, the equivalent CO2 emissions compared to HFC-134a in low-temperature space heating applications, and down to 78% compared to a natural gas boiler as conventional heating technology in moderately high temperature applications (domestic hot water, industrial processes, and radiators). Although HFO-1234ze(E) and R-515B present comparable efficiency and environmental performance, R-515B, exhibits an advantage in installation safety requirements as a non-flammable refrigerant (A1).