Performance limits of absorption cycles with external heat-transfer irreversibilities

Abstract

Heat-transfer irreversibilities are included in the analysis of the ideal absorption refrigeration cycle working with three heat reservoirs. Expressions arc obtained for the COP at a given cooling capacity and the COP at the maximum cooling capacity in terms of four non-dimensional design and operating variables. The condition for the maximum cooling capacity depends only on the temperature ratios. The predictions of the model are compared with data obtained by detailed computer simulation of single-stage and double-stage absorption refrigeration machines. The predicted variation of the maximum cooling capacity with reservoir temperatures follows the same linear variation obtained by computer simulation. The COPs of single-stage and double-stage machines lie between the predicted COP at the maximum cooling capacity and the COP at the given cooling capacity. The COPs of real machines are much closer to the predicted values than to the COP of the reversible cycle operating between the same three heat reservoirs.