The optimum performance characteristics of a four-temperature-level irreversible absorption refrigerator at maximum specific cooling load

An irreversible cycle model of an absorption refrigerator operating between four temperature levels is established and used to analyse the performance of the refrigerator affected by the irreversibility of finite-rate heat transfer and the internal irreversibilities of the working substance. The specific cooling load of the refrigerator is taken as an objective function for optimization. The maximum specific cooling load is determined. Other main parameters of the refrigerator at maximum specific cooling load are calculated. The optimal distribution relation of the heat-transfer areas of the heat exchangers is derived. Several special cases are discussed in detail so that some important conclusions relative to absorption refrigerators in the literature may be derived directly from the present paper. Moreover, the influence of the internal irreversibilities on the performance of the system is analysed. The results obtained here can describe the optimal performance of a four-temperature-level absorption refrigerator affected simultaneously by the internal and external irreversibilities and provide the theoretical bases for the optimal design and operation of real absorption refrigerators operating between four temperature levels.