Multi-Objective Optimization Design for Indirect Forced-Circulation Solar Water Heating System Using NSGA-II

Abstract

Abstract:In this study, the multi-objective optimization of an indirect forced-circulation solar water heating (SWH) system was performed to obtain the optimal configuration that minimized the life cycle cost (LCC) and maximized the life cycle net energy saving (LCES). An elitist non-dominated sorting genetic algorithm (NSGA-II) was employed to obtain the Pareto optimal solutions of the multi-objective optimization. To incorporate the characteristics of practical SWH systems, operation-related decision variables as well as capacity-related decision variables were included. The proposed method was used to conduct a case study wherein the optimal configuration of the SWH system of an office building was determined. The case study results showed that the energy cost decreases linearly and the equipment cost increases more significantly as the LCES increases. However, the results also showed that it is difficult to identify the best solution among the Pareto optimal solutions using only the correlation between the corresponding objective function values. Furthermore, regression analysis showed that the energy and economic performances of the Pareto optimal solutions are significantly influenced by the ratio of the storage tank volume to the collector area (RVA). Therefore, it is necessary to simultaneously consider the trade-off and the effect of the RVA on the Pareto optimal solutions while selecting the best solution from among the optimal solutions.

Investigation of the Dynamic Melting Process in a Thermal Energy Storage Unit Using a Helical Coil Heat Exchanger

“…Over the last decade, a variety of solar energy utilization systems have been extensively used in actual applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. These systems are deemed to be an attractive approach for solving global energy shortage problems due to its renewable and sustainable nature.…”

Numerical and Experimental Study on a Solar Water Heating System in Lhasa

“…Solar water storage tanks are widely used for solar heating systems due to their low cost and convenience [13][14][15]. The temperature distribution of the solar water storage tank is key to the design and operation of a solar heating system [16][17][18][19][20], and mathematical models are essential for the analysis of the temperature distribution in the heat storage tank [21][22][23]. One-dimensional finite volume discretization is the most common model of a stratified storage tank [24][25][26][27][28][29][30], which greatly reduces the model complexity but thus implies that three dimensional effects, like jet mixing and buoyancy, require model adaptations or correlations [31].…”