residential heat pump, refrigerant alternatives, DR-5A, L41-2, drop-in tests
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 and air-conditioners as R-410A has a GWP of 2088. In this study, two promising alternative refrigerants with a low-GWP, DR-5A (R-454B) and L41-2 (R-447A), both HFC-HFO mixtures with a GWP of 466 and 583 respectively, have been tested in a residential heat pump. Â To assess and to compare the heat pump performances using R-410A, DR-5A and L41-2, drop-in tests have been carried out in a 10 kW air-to-water reversible heat pump. For each refrigerant, the heat pump performances have been assessed for 2 rating conditions and 2 operating limit conditions in the cooling mode and for 6 rating conditions and 3 operating limit conditions in the heating mode. The tests have been performed according to the ENÂ 14511 standard. This experimental investigation has been carried out in three phases. In the first one, the performances of the heat pump using R-410A have been evaluated. Then, in phases 2 and 3, both alternative refrigerants, DR-5A and L41-2, have been tested. For each, a refrigerant charge optimization has been done, then the rating and operating limit condition tests have been performed, and finally, a performance verification using R-410A has been carried out to detect any anomaly after the use of one or the other of these alternative refrigerants. During all the tests, measurements have allowed to determine the thermal capacities, the electric energy consumptions, the efficiencies (EER or COP), as well as the refrigerant circuit pressures and discharge temperatures. Â A total of 39 tests have been performed. The refrigerant charge optimization drives to decrease the charge in the heat pump by 15% for DR-5A and by 21% for L41-2 in comparison with R-410A. The results show that R-410A replacement by L41-2 and DR-5A do not raise any particular problem even in operating limit condition tests and the performances obtained are, aside from some exceptions, almost equivalent (+/- 10%) to those of R-410A. Globally, DR-5A shows higher capacities and performances than L41-2.