Evaluation and Soft-Optimization for R410A Low-GWP Replacement Candidates through Testing and Simulation

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) announced an industry-wide cooperative research program to evaluate alternative refrigerants that have low global warming potential (GWP). R410A is a common refrigerant for air conditioning and heat pumping application but has a GWP of 2088. Drop-in tests of three R410A low-GWP alternative refrigerants (R32, D2Y60 and L-41A) in a 3 ton split heat pump unit are performed according to ASHRAE Standard 116-1995 test matrix. The test matrix is expanded to include extended cooling and heating conditions which represent extreme weather conditions. The results show that R32 and L-41A are good replacement candidates for R410A. However, the capacity of D2Y60 is lower than that of R410A by an average of 18% for cooling and 14% for heating. An in-house component based vapor compression system simulation tool is validated against the experimental data. The heat exchanger model used in the system simulation uses an in-house finite volume model. The compressor model uses the 10-coefficient R410A compressor map. A total of 32 experiments are used in the validation. The results of the validation are in good agreement with the experiments. Most of the predicted COP and capacity results lie within 5% of the measured values. The largest error is in the case of low temperature and extended condition tests because the mass flow rates were estimated and not measured. Soft optimization options, by varying the size of the compressor, are carried out to match the capacity to that of R410A. As the compressor size increases, the mass flow rate, power consumption, and capacity increase, while the COP decreases