Performance Ranking of Refrigerants With Low Global Warming Potential
Mark A. Kedzierski, J S. Brown, Junemo Koo
This paper evaluates in a typical air-conditioner the cycle performance of thirty-nine refrigerants identified in the AHRI Low Global Warming Potential (GWP) Alternative Refrigerants Evaluation Program (Low-GWP AREP). The Low-GWP AREP was initiated in response to environmental concerns raised by the use of high-GWP refrigerants with the intent to identify and evaluate promising alternative refrigerants. The cycle performance of each refrigerant is calculated assuming the same evaporator heat duty and sink temperatures for the condenser. The evaluation included the effects of heat transfer and pressure drop in the evaporator and the condenser. Four performance variables were investigated: (1) the coefficient of performance; (2) the required volumetric displacement of the compressor; (3) the average temperature difference of the evaporator; and (4) the compressor discharge superheat. Bar charts of the above four parameters relative to the refrigerants that are intended to be replaced were provided for each replacement refrigerant. In addition, a methodology was developed using weighing factors to rank the alternative refrigerants either emphasizing the importance of large COP or the importance of reduced system size. The two ranking methodologies produced different rankings of the alternative refrigerants; however, the top three ranked refrigerants had at least one refrigerant in common with each other. The methodology identified R1234yf, R32, and R1270 as having ranking factors within those of the best-three alternative refrigerants for both methodologies.