| Abstract: | In this study, 14 refrigerant mixtures composed of R32, R125, R134a, R152a, R290 (propane) and R1270 (propylene) were tested in a breadboard heat pump in an attempt to substitute HCFC22 used in residential air-conditioners. The heat pump was of 3.5 kW capacity with water as the heat transfer fluid (HTF) in the evaporator and condenser that are in a counter current flow configuration. All tests were conducted with the HTF temperatures fixed to those found in the ARI test A condition. Test results show that ternary mixtures composed of R32, R125, and R134a have a 4–5% higher coefficient of performance (COP) and capacity than HCFC22. On the other hand, ternary mixtures containing R125, R134a and R152a have both lower COPs and capacities than HCFC22. R32/R134a binary mixtures show a 7% increase in COP with the similar capacity to that of HCFC22 while R290/R134a azeotrope shows a 3–4% increases in both COP and capacity. The compressor discharge temperatures of the mixtures tested are much lower than those of HCFC22, indicating that these mixtures would offer better system reliability and longer life time than HCFC22. Finally, test results with a suction line heat exchanger (SLHX) indicate that SLHX must be used with special care in air-conditioners since its effect is fluid dependent. |
