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Evaluation of Flammable Refrigerants for Use in a Water-to-Water Residential Heat Pump.

pdf icon Evaluation of Flammable Refrigerants for Use in a Water-to-Water Residential Heat Pump. (648 K)
Choi, D. K.; Domanski, P. A.; Didion, D. A.

International Institute of Refrigeration. Applications for Natural Refrigerants. Proceedings. September 3-6, 1996, Aarhus, Denmark, 467-476 pp, 1996.


refrigerants; heat pumps; water; evaluation; cooling; heating; test facilities


This paper evaluates the performance of R-22, R-290, R-290/600a (70/30), and R-32/152a (50/50) for application in a water-to-water residential heat pump for space cooling and heating. The tests were performed in a laboratory apparatus at different compressor speeds to allow the comparison of refirgerants for the constant-compressor-speed and the constant-capacity criteria. Comparison of results for the same system capacity showed R-32/152a to be the best performer due to good glide matching in the heat exchangers and its excellent thermodynamic and transport properties. The hydrocarbon mixture, R-290/600a, had the highest Coefficient of Performance (COP) at a given compressor speed, but its COP at the constant-capacity criterion was the lowest. This low COP was in disagreement with an earlier simulation study where R-290/600a and R-32/152a had a similar COP. The test data showed that the low-volumetric-capacity R-290/600a had an excessive pressure drop at the constant-capacity comparison. This was related to the high compressor RPM needed for R-290/600a to reach the target capacity. With an optimized compressor and heat exchangers using larger diameter tubes, R-290/600a should have a COP comparable to that of R-32/152a. The study demonstrates the need for both simulations and laboratory methods in evaluating alternative refrigerants.