Testing of a hydrocarbon mixture in domestic refrigerators

Abstract

Performance of a propane/isobutane (R-290/R-600a) mixture was investigated in domestic refrigerators. Thermodynamic cycle analysis indicated that the R-290/R-600a mixture in the composition range of 0.2 to 0.6 mass fraction of R-290 yields an increase in the coefficient of performance (COP) of 1.7% to 2.4% as compared to R-12. For the actual performance tests, two refrigerator units (299 liters and 465 liters, respectively) were used. For both units, all refrigeration components remained the same throughout the tests, except that the length of the capillary tube and the amount of charge were changed for the mixture. Each refrigerator was fully instrumented with more than 20 thermocouples, 2 pressure transducers, and a digital watt/watt-hour meter. For each unit, both an energy consumption test and a no-load pull-down test were performed under the same conditions. The experimental results obtained with the same compressor indicated that the R-290/R-600a mixture at 0.6 mass fraction of R-290 showed a 3% to 4% increase in energy efficiency and a faster cooling rate as compared to R-12. The R-290/R-600a mixture showed a shorter compressor on-time and lower compressor dome temperatures than R-12. In conclusion, the proposed hydrocarbon mixture seems to be an appropriate candidate to replace R-12 from themore » viewpoint of energy conservation.« less