The optimum performance of absorption cycles with external and internal Irreversibilities

A new model is presented to describe an irreversible absorption refrigerator, in which not only the irreversibilities of heat conduction but also the irreversibilities resulting from the friction, eddy and other irreversible effects inside the working fluid are considered. The influence of these irreversible effects on the performance of an absorption refrigerator with continuos flow is investigated. The analytical expressions of the optimal refrigeration coefficient and the cooling rate of the refrigerator are derived. The predictions of the model are compared with semi-empirical cycle model of single-stage absorption refrigeration machines. The results obtained here can describe the optimal performance of a four-temperature-level absorption refrigeration affected simultaneously by the internal and external irreversibilities and provide the theoretical base s for the optimal design and operation of real absorption refrigerators operating between four temperature level.