Optimization of irreversible four-heat-source absorption refrigerator with finite heat capacity

A model for the absorption refrigerator treated as an irreversible Carnot refrigerator driven by an irreversible Carnot heat engine was established using the finite-time thermodynamic approach. Considering not only the effects of the external and internal irreversibilities but also the effect of the finite heat capacity, the established model is a general thermodynamic model that is close to the real systems. Two internal irreversibility parameters, the heat engine cycle and the refrigerator cycle were introduced to characterize the irreversibility inside the cycle. Using the established mode a basic optimization relationship of the absorption refrigerator and corresponding conditions for the optimal design and the optimal working temperature of the working fluid in the heat exchanger were derived by the Lagrangian multiplier method. Some simplified relationships for the optimal design and the improvement of the actual absorption refrigerator were also deduced.