Multi-objective analysis and optimization of performance of a multiirreversible absorption heat pump

Abstract

In this work, a theoretical analysis and a multi-objective optimization of three-heatreservoir absorption heat pump (THR AHP) and four-temperature-level absorption heat pump (FTL AHP) were carried out under real operating conditions. It highlights the different thermodynamic cycles including the inversed Carnot, Brayton, Stirling and Ericsson cycles. In fact, the non-insignificant increase in absorption systems such as refrigeration, air conditioning and heat pump which is the subject of our attention is presented as ecological, economical and environment-friendly systems. In addition, multi-objective optimization, particularly for AHP, is established by first considering the thermo-ecological criterion for THR AHP, then the exergetic criterion for FTL AHP. Futhermore, the simultaneous analysis of ecological, exergetic and economic criteria is considered. Indeed, the different criteria are highlighted analytically using finite time thermodynamics (FTT). This made it possible to determine the optimal operating points of the system by minimizing exergy destruction rate, entropy generation rate, the environmental impact and the costs of capital and energy consumed. Also, the parameters taken into account influencing the performance of the absorption heat pump are the finite heat resistances, the heat leakages, the thermo-economic parameter, the ratio of heat rejected between the absorber and the condenser for FTL and the two internal irreversibility factors in particular that between the evaporator-condenser assembly for THR. However, the flowchart optimization methodology made it possible to deduce that the system has a significant advantage at the maxima of the thermoeconomic and exergetic criteria in terms of coefficient of performance. Nevertheless, THR AHP presents a significant advantage at the maximum of the exergetic criterion in terms of exergy destruction rate and at the maximum of the ecological criterion in terms of specific heating load and exergy output rate. These results could make it possible to improve the design and sizing of AHP, especially on the nature of the materials used and the difference in the temperature-level of the working fluid circulating in the absorber and the condenser.