OPTIMAL HEAT-TRANSFER AREAS FOR ENDOREVERSIBLE HEAT-PUMPS

The influence of thermal resistance on the performance of a heat pump operating with three heat sources is investigated by using an endoreversible cyclic model with continuous flow. The overall heat-transfer area of the heat pump is chosen as an objective function for optimization. For a specified COP and rate of heat pumping, the expression for minimum overall heat-transfer area of the heat pump is derived. This expression is used (a) to discuss the optimal performance of an endoreversible heat pump operating with three heat sources and (b) to deduce the optimal performance of a Carnot heat pump with continuous flow. The results obtained here may be useful for exploitation of heat pumps driven by low-grade heat from the sun, geothermal energy or waste heat and also for improvement of heat pumps driven by high-grade energy sources.