Internal irreversibilities’ influence on the new thermo-ecological criterion for real absorption refrigerators

Abstract

Irreversibility is classified in two main types: internal and external irreversibilities. Internal irreversibility is due to turbulence, pressure gradients, mixing and diffusion processes within the system, which is represented by two irreversibility parameters indicating the deviation from an endoreversible case. This paper studies and analyses the effects of two internal irreversibility parameters (the internal irreversibility parameter for generator–absorber assembly and the internal irreversibility parameter for condenser–evaporator assembly) on the optimal ecological performances of an irreversible four-heat-source absorption refrigerator based on the ecological coefficient of performance (ECOP) criterion. The ECOP objective function is defined as the ratio of the cooling load to the loss rate of availability (or entropy generation rate). The results obtained show that the internal irreversibility parameter for condenser–evaporator assembly affects more the ecological performance of the system than the internal irreversibility parameter for generator–absorber assembly. This is of importance to the optimal design and performance improvement of absorption refrigeration cycles.

Keywords:

• absorption refrigeration system
• internal irreversibility
• optimisation
• ecological coefficient of performance

Acknowledgements

The present research work was carried out in LISIE and LESEE. All the senior researchers of these laboratories are gratefully acknowledged for their helpful comments. We also thank the administrators of these laboratories for the opportunity.