Performance of alternative refrigerant mixtures for HCFC22

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. T he 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 con figuration. All tests were conducted with the HTF temperatures fixed to tho se found in the ARI test A condition. Test results show that ternary mixtur es composed of R32, R125, and R134a have a 4-5% higher coefficient of perfo rmance (COP) and capacity than HCFC22. On the other hand, ternary mixtures containing R125, R134a and R152a have both lower COPs and capacities than H CFC22. 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% increas es in both COP and capacity. The compressor discharge temperatures of the m ixtures tested are much lower than those of HCFC22, indicating that these m ixtures would offer better system reliability and longer life time than HCF C22. Finally, test results with a suction line heat exchanger (SLHX) indica te that SLHX must be used with special care in air-conditioners since its e ffect is fluid dependent. (C) 2000 Elsevier Science Ltd and IIR. All rights reserved.