Abstract: On the basis of an endoreversible absorption refrigeration cycle, an irreversible four-heat-reservoir cycle model is built by taking account of the heat resistance, heat leak and irreversibilities due to the internal dissipation of the working fluid. The fundamental optimal relation between the coefficient of performance and the cooling load, the maximum coefficient of performance with its corresponding cooling load, and the maximum cooling load with its corresponding coefficient of performance of the cycle coupled to constant-temperature heat reservoirs are derived by using finite-time thermodynamics. The optimal distribution of the heat-transfer surface areas is also obtained. Moreover, the effects of the cycle parameters on the coefficient of performance and the cooling load of the cycle are studied through detailed numerical examples. The results can provide the theoretical bases for the optimal design and operation of a real absorption refrigerator operating at four temperature levels.

Key words: four-heat-reservoir refrigeration cycle, heat leak, internal irreversibility, finite-time thermodynamics