Multi-objective optimization of a solar hybrid CCHP system based on different operation modes

Abstract

Abstract This paper carries out a multi-objective optimization of a solar hybrid combined cooling, heating and power (CCHP) system, based on the objective functions of annual cost saving ratio (CSR) and primary energy saving ratio (PESR). The system is modeled in three modes: 1) following electrical load (FEL); 2) following thermal load (FTL) and 3) following thermal load and selling power to grid (FTL-S). Non-dominated Sort Genetic Algorithm- II (NSGA-II) is adopted to find the Pareto front solutions of the potentially optimal configuration and corresponding criteria. The results show a conflict between cost saving and fuel saving. By selecting the compromised optimal point, the CSR increases to 25.04% and the PESR increases to 37.86% on average. The system in FEL mode performs best in energy saving and the system in FTL-S mode performs best in economy. The solar hybrid CCHP system is also compared with other three systems: 1) conventional CCHP system; 2) CCHP system with photovoltaic assisted only and 3) CCHP system with solar collector assisted only. In the end, the sensitivity analysis is implemented and the results present that energy prices and the efficiency of major equipment have varying degrees of impact on system performance.