Optimization of heat transfer areas in three-heat-source absorption refrigerator

An irreversible model of three heat source absorption refrigerator is set up and driven by low grade heat energy.The impact of both irreversibilities of heat conduction and irreversibilities resulting from friction, eddy and other irreversible effects inside the working fluid on cyclic performance of a three heat source refrigerator with continuous flow is studied. The total heat transfer area of the three heat exchangers is taken as an objective function for optimization. The minimum heat transfer area is described in terms of the rate of the entropy changes of the three heat sources, and then an analogue of the second law of thermodynamics is derived. The optimal relation between rate of refrigeration, the coefficient of performance and heat transfer areas is achieved. The influence of the internal irreversibilities on the performance of the system is discussed. The results obtained can be used to describe the optimal performance of a three heat source absorption refrigerator affected simultaneously by the internal and external irreversibilities and can provide some new theoretical approach to the optimization design and performance improvement of real three heat source absorption refrigerator.