Optimal performance of irreversible absorption refrigerator with four heat sources

A model for an irreversible four-heat-source absorption refrigerator with continuous flow, which considers the irreversibilities resulting from thermal resistance and internal dissipations of the working fluid, is established. In this model, an absorption refrigerator is treated as a combined cycle system of an irreversible Carnot heat engine driving an irreversible Carnot refrigerator. Two parameters I he and I r are introduced to characterise the internal irreversibilities of the heat engine and refrigerator in the equivalent cycle system respectively. Under a given total heat conductance of the heat exchangers, the optimal relation between the cooling rate and coefficient of performance is derived, and the conditions for the optimal design of the system are determined. Then, this relation is used to deduce some new performance bounds. Moreover, the effects of the internal irreversibility parameters I he and I r on the optimal performance of the system are also investigated. The results obtained here are important for the optimal design and performance improvement of a real absorption refrigerator.