Experimental evaluation of R410A, R407C and R134a alternative refrigerants in residential heat pumps
residential heat pump, refrigerant, drop-in, experiment
Protocols and regulations such as the Montreal Protocol (1987), the Kyoto Protocol (1997), the European F-gas regulation (2006) and now its revision (2014) cause a shift toward refrigerants with both zero Ozone Depletion Potential (ODP) and low Global Warming Potential (GWP). Alternative refrigerants with low-GWP are under investigation for residential heat pumps, air-conditioners and heat pump water heaters as R410A, R407C and R134a have GWP of 2088, 1650 and 1430, respectively. In this study, five alternative refrigerants: R459A, R454B, R447A, HPR2A and R32, with GWP of 460, 466, 583, 600 and 675, respectively, were investigated for the replacement of R410A in a 10 kW Air-to-Water (A/W) reversible heat pump. Two alternative refrigerants of R134a: R1234yf and R513A with GWP of 4 and 631, respectively, were tested in a split Heat Pump Water Heater (HPWH) having a water tank of 200 L. R454C with a GWP of 148 was evaluated as a possible alternative to R407C in a 3 kW Water-to-Air (W/A) reversible heat pump. To assess and to compare the performances, drop-in tests were carried out. For each heat pump and refrigerant, a charge optimization was performed prior to the performance tests and finally, a performance verification using the base refrigerant was carried out to detect any anomaly after the use of each alternative refrigerant. For the A/W and the W/A heat pumps, the tests were performed according to the EN 14511 standard and for the HPWH, the tests consisted in heating up of the tank. During all tests, measurements allowed the determination of cooling / heating capacities, electric power inputs and efficiencies (EER/ COP). Refrigerant pressures and discharge temperature were also recorded. A total of 8 alternative refrigerants with low-GWP were evaluated with not less than 114 performance tests. The experimental results are useful for the HVAC community for facilitating the selection of the most promising candidates for drop-in replacement of R410A, R134a and R407C.