Performance of Heat Pumps at Elevated Evaporating Temperatures—With Application to Solar Input

As part of the study of Solar Assisted Heat Pump (SAHP) systems, the performance of the heat pump component itself under conditions attendant to series solar input is being investigated. Notably the effect of high source temperatures, for which current heat pumps are not designed, and the associated thermodynamic potential to raise performance are of interest. This paper presents theoretical predictions, results of systematic experiments run on a special heat pump simulator, and interpretation/analysis of how high Coefficients of Performance (COP) heat pumps can be used in installed SAHP systems. The latter aspect is vital for—although results have shown that substantial increase in COP can be achieved even using off-the-shelf heat pump components—the more difficult problem is supplying sufficient solar energy to the heat pump with a practical, cost-competitive system. The approach taken to the high temperature heat pump study makes the results generally applicable to any vapor compression heat pump with related evaporating temperatures.