System Performance of Some Long Term R-502 Replacements

A series of tests has been completed comparing the system performance of four long term replacements HP62 (44% R~125/ 54% R-143a/ 4% R-134a), AZ-50 (50% R-125/ 50% R-143a), Klea 60 (20% R-32/ 40% R-125/ 40% R-134a), and Klea 61 (1 0% R-32/ 70% R-125/ 20% R-134a) as potential alternatives for the CFC-containing low temperature refrigerant R-502. The tests were carried out under controlled conditions in a well-instrumented alternative refrigerants test facility, using an open-drive reciprocating compressor and counter-flow heat exchangers. Measurements were conducted at two different condensing temperatures: 54.4°C (130.0°F) and 43.3°C (11 O.Q°F). The refrigerant evaporating temperature was varied over a range of -30.0°C to -15.0°C (-22.0°F to 5.0°F). Test data were used to compare important system performance characteristics with R-502 including relative evaporator capacity, relative cooling coefficient of performance (COP), and compressor discharge temperature. The effect of additional refrigerant liquid subcooling on the evaporator capacity and COP was also evaluated.