Thermodynamic Analysis of a Direct Expansion Solar Assisted Heat Pump Water Heater

In this article the thermodynamic performance of a direct expansion solar assisted heat pump (DX-SAHP), which is used to heat domestic water from 20˚C to 45˚C, is theoretically investigated. The system includes a3m 2 single-cover flat plate solar collector, 150 liter water tank and 70 meters tube immersed in the water tank as condenser. Effect of various parameters such as received irradiance on the collector surface, compressor speed and the ambient temperature on the coefficient ofperformance (COP) is calculated. Results show that obtained COP is considerably more than that of a conventional heat pump water heaterwhen radiation on collector is high and increasing collector area and ambient temperature and reducing compressor speed enhance COP.For instance, at 450 W/m2 received irradiance on collector and 15˚C ambient temperature, the calculated COP is 6.37.