Multi-objective optimization of a small sized solar PV-T water collector using controlled elitist NSGA-II coupled with TOPSIS

Abstract

Small-sized solar photovoltaic thermal (PV-T) collector can achieve better overall performance due to less aperture plane heat losses and the possibility of concentrating more radiant flux per unit aperture area compared to their large counterpart designs. Despite its potential, studies on its performance optimization have not yet been explored. This study aims to perform a multi-objective optimization of the performance of a small-sized PV-T water collector with channel type absorber design by using a two-step procedure i.e., implementation of Non dominated sorting genetic algorithm (NSGA-II) followed by a decision making method i.e., a technique for order preference by similarity to ideal solution (TOPSIS). Based on the Taguchi orthogonal array design for three control parameters i.e., mass flow rate, inlet temperature, and inclination angle, an experimental campaign is undertaken. The design space created on the basis of Taguchi design of experiment is used to conduct a total 16 number of experiments. An analysis of variance is carried out to obtain the significant design and operating parameters controlling the collector performance, which are used to fit the objective function equations for both thermal and electrical efficiency. A multi objective optimization strategy is then developed by a variant of NSGA-II to simultaneously optimize its average thermal and electrical efficiencies. From the obtained Pareto fronts, the most optimal solution is obtained by using TOPSIS method. The highest thermal and electrical efficiency of 82.55% and 10.45% is obtained under an optimal mass flow rate of 0.02 kg/s, inlet temperature 32 °C and inclination angle 38.88°. The influence of solar radiation on its optimized performance demonstrates a little less higher thermal efficiency of 81.05% and electrical efficiency of 11.43% obtained at a radiation of 700 W/m2. On experimental verification of the optimized performance, the highest thermal and electrical efficiency is obtained within an agreement of ± 3.51% and ± 6.9%, respectively. The present optimized efficiency values are higher compared to that of a typical experimental day with un-optimized input conditions and also higher than some of the recent published papers.