Investigation of the potential effect of zeotropic refrigerant mixture on performance of a hot water heat pump

Abstract

The refrigerant R-22, which is currently being used in hot water heat pumps, delivers hot water at temperatures of 60--65 C (140--149 F). This temperature is adequate for domestic use but is low when compared to temperatures that can be delivered by fossil fuel and direct electric resistance systems. This limits the potential applications of hot water heat pumps. In this study, it is shown analytically that a zeotropic mixture of R-22 and R-142b can be used to obtain higher temperatures. It was found that in certain cases, depending on the concentrations, not only are increased hot water temperatures possible, but an improved heating capacity as well as an improvement in the coefficient of performance are also possible.