Optimal ecological performance of a four-temperature-level absorption heat pump

The new thermo-ecological performance optimization that combines first and second law of thermodynamics has been carried out for an irreversible absorption heat pump operating between four-temperature-levels. Multi-irreversibilities considered in the system include finite-rate transfer, heat leakage and internal dissipations. The ecological coefficient of performance ECOP defined as the ratio of the heating load to the loss rate of availability (or entropy generation rate) is considered as the objective function. The goal of the new thermo-ecological performance optimization is to maximize this objection function with respect to the working fluid temperatures in the main components of the system. The maximum ECOP and the corresponding optimal coefficient of performance, specific heating load, specific entropy production rate and heat-transfer areas have been determined analytically. The effects of the internal irreversibility, the heat leakage coefficient, the source temperature ratios, the overall heat-transfer coefficients of the heat-exchangers and the distribution ratio rate of the total heat-reject quantity between the absorber and the condenser on the global and optimal performances have been analyzed and discussed. (C) 2011 Elsevier Masson SAS. All rights reserved.