3700 -- Cycle Performance Testing of Nonazeotropic Mixtures of HFC-143a/HCFC-124 and HFC-32/HCFC-124 with Enhanced Surface Heat Exchangers PDF

In an effort to improve the efficiency of residential heat pumps using alternative refrigerants, two nonazeotropic refrigerant mixtures (NARMs) were tested over a range of heat exchanger capacities to determine their cooling mode performance at U.S. Department of Energy (DOE) heat pump rating conditions of 82 degF (27.8 degC). The two mixtures, R32/R124 (30%/70%) and R143a/R124 (75%/25%), were selected on the basis of a previous study that screened refrigerant pairs using such factors as boiling point, stability, ozone-depletion potential (ODP), and coefficient of performance (COP) to determine suitable candidates for residential heat pump performance. Three refrigerant-side heat transfer enhancements were tested to determine their effects on overall system performance. Comparisons were made on the basis of COP as a function of capacity. Summarises the findings.

KEYWORDS: Testing, performance, refrigerants, mixtures, non azeotropic, heat exchangers, R143a, R124, efficiency, domestic, heat pumps, coefficient of performance.