Studies of a heat pump using water and air heat sources in parallel

The mechanism of heat pumps for hot water supply using dual heat sources of the ambient air and water and the operating conditions of selecting either one or both heat sources were discussed. Then, the performance of a heat pump which used water and the ambient air as the heat sources to heat water was examined experimentally. When the temperature of the water heat source was decreased, the heat from the water as well as the heat from the air was used for the heat pump efficiently until its temperature became approximately that of the evaporation temperature of the heat pump using the ambient air alone as the heat source. When the temperature of the water dropped further, only the heat from the air was absorbed by the evaporators like an ordinary heat pump which used only the evaporator of the air heat source at the same ambient air temperature. A theoretical analysis was made on the performance of a heat pump with dual heat sources. The results agreed well with the experimental results. © 2000 Scripta Technica, Heat Trans Asian Res, 29(6): 473–490, 2000