Performance-based Pareto optimization and multi-attribute decision making of an actual indirect-expansion solar-assisted heat pump system

Abstract

This study presents the sensitivity analysis and simulation-based Pareto optimization of an actual indirect-expansion solar-assisted heat pump (IX-SAHP) water heater. The developed IX-SAHP is validated and its performance is fully appraised in a humid continental climate zone throughout the year. Next, the one-factor-at-a-time (OFAT) method is implemented to determine the impacts of various design parameters of IX-SAHP on the system performance. Then, the impacts of several major input variables on the pressure drop of refrigerant flow in the IX-SAHP are evaluated. Additionally, the single and multiple-objective particle swarm optimizations (MOPSO) are integrated with the designed IX-SAHP to optimize the coefficient of performance (COP) and the solar collector efficiency (SCE), separately and concurrently to achieve the optimal non-dominated solutions in the form of Prato front. Afterward, the final optimum configuration is chosen through TOPSIS integrated with the MOPSO using programming under MatLab environment. The comparison of achieved solutions shows that the multi-objective optimization gives more appropriate and reliable solutions compared to the single one. Also, the Pareto optimization results show that whereas the SCE diminishes slightly from 52% to 46.4%, but the COP highly improves from 3 to 7 which lead to a significant reduction in the overall operating hour of the IX-SAHP approximately 270 h throughout the year compared to the initial IX-SAHP model.