Heat Pump

One of the limitations of using refrigerant mixtures to achieve capacity modulation is that the range of capacity control and the temperature glide are both functions of the difference For applications in residential heat pumps, in boiling points of the two pure components. the temperature glide for the mixture should not exceed 30 F (16.7°C) (Radermacher 1986). Operation at. temperature glides above 30 F (16.7°C) would result in situations where the temperature difference of the mixture exceeds that occurring in the source, resulting in a Thus, the amount of capacity control is limited by the degree to decrease in efficiency. which the boiling points of the two refrigerants can differ without causing the mixture to exceed a temperature glide of 30 F (16.7°C). The mixture .R13Bl/R152a was selected for analysis because of its difference in boiling points for the pure components, which allowed for a moderate degree of capacity modulation without exceeding a temperature glide of 30 F (16.7°C). In addition, sufficient data on this mixture were known to permit a determination of property data using subroutines developed by We recognize that the mixture is composed of two components Morrison and McLinden (1986). that pose potential problems. R13B1 has been mentioned as being potentially damaging to the ozone layer, while R152a could present risks to safety due to flammability. However, since this mixture had the potential for matching all our objectives, we felt it should be tested in order to quantify the potential gains in efficiency from capacity modulation via composition shifting.

TEST FACILITY

The test rig, depicted in Figure 3, consists of the following equipment:
Compressor

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reciprocating 1.134-in3 (18.6 mL) displacement 10,000 Btu/h (2931 W) rated for R22 at -130 F (54.4°C) condensing temperature - 45 F (7.2°C) evaporating temperature - 95 F (35°C) ambient temperature

Condenser and Evaporator * * * * * * coaxial tube-in-tube, turbolators on...