Advanced exergy analysis of an absorption cooling machine: Effects of the difference between the condensation and absorption temperatures

• The advanced exergy analysis has been applied to the water–LiBr absorption cooling machine.
• The endogenous and exogenous exergy destruction rates are calculated at each cycle component.
• For each component, the exergy destruction has been characterized as avoidable or unavoidable.
• The desorber and absorber are identified as the components with the largest exergy destruction.
• The effects of the temperature difference between the condenser and the absorber are discussed.

The water–LiBr absorption machine was analyzed with the purpose of identifying the endogenous, exogenous, avoidable and unavoidable fractions of the exergy destruction. The latter was observed to be largely of endogenous nature, with the desorber and absorber being the major contributors. When the difference between the absorption and condensation temperatures was raised, both the first and second law efficiencies degraded. Furthermore, the absorber endogenous avoidable irreversibility was much larger than that at the desorber when the absorption temperature was lower than the condensation temperature, and the situation reversed when the absorption temperature became higher than the condensation temperature. The same trends were observed in terms of the exogenous avoidable exergy destruction. However, the endogenous unavoidable exergy destruction at the absorber was initially smaller than that at the desorber, and the two components equally contributed to the total endogenous unavoidable irreversibility when the absorption temperature became higher than the condensation temperature.