Testing was performed with a nonazeotropic refrigerant mixture of R13B1/R152a to determine its ability to achieve (1) capacity control by adjusting the composition and (2) increased capacity, relative to R22, at low ambient temperatures. The selection of such a mixture could improve the efficiency of a heat pump by decreasing the cycling losses, which account for approximately 7-12% of the annual energy use, along with decreasing the amount of resistance heat required at low ambient temperatures. Results for the mixture show a potential capacity modulation from 12431 Btu/h (3643 W) at 17°F (-8.3°C) to 8550 Btu/h (2506 W) at 47°F (8.3°C) in heating and from 7451 Btu/t (2184 W) at 82°F (27.8°C) to 9188 Btu/h (2693 W) at 95°F (35°C) in cooling. An analysis of the coefficients of performance for the mixture and its pure components is presented along with a comparison against results obtained with R22. The comparison is based on maintaining equivalent inlet and exit water temperatures in the evaporator and condenser for both R22 and the mixtures.

Units: Dual