The optimum performance characteristics of a two-stage absorption refrigerator

An irreversible cycle model of a two-stage absorption refrigerator is set up and used to analyze the performance of the refrigerator affected by the irreversibility of finite-rate heat transfer and the internal irreversibility of the working material.The total thermal conductance of the six heat exchangers is taken as an objective for optimization.The minimum total thermal conductance is described in terms of the rate of the entropy changes of the six heat reservoirs,and then an analogue of the second law of thermodynamics is derived.The optimal relation among the rate of cooling load,the coefficient of performance and the total thermal conductance is achieved.The influence of the internal irreversibility on the performance of the system is discussed.The results obtained can describe the optimal performance of a two-stage absorption refrigerator affected simultaneously by the internal and external irreversibilities and can provide some new theoretical approach of the optimization design and performance improvement of real two-stage absorption refrigerator.