Multi-objective RSM optimization of fin assisted latent heat thermal energy storage system based on solidification process of phase change Material in presence of copper nanoparticles

In the present study, the discharging process of Latent Heat Thermal Energy Storage System (LHTESS) containing Phase Change Material (PCM) is investigated numerically. These systems are used to establish balance between energy supply and demand. Conventional PCMs have high latent heat but low thermal conductivity. This feature weakens heat transfer mechanisms of LHTESS during charging and discharging processes. In this paper, a novel fin configuration is optimized by multi-objective Response Surface Method (RSM) based on discharging process of LHTESS, and then this fin configuration is applied to LHTESS. Comparison between full discharging time by applying this fin array and LHTESS with other fin structures is carried out. Then nanoparticles is dispersed into the PCM to enhance heat transfer during solidification process and comparison between adding nanoparticles to LHTESS and immersing fin is carried out. Standard Galerkin Finite Element Method is used to provide numerical simulation of solidification phenomenon in the present study and Adaptive Grid Refinement is employed to solve the governing equations. Since immersing fin into the LHTESS reduces the amount of PCM mass and as a result, reduces the value of maximum energy storage capacity, in this work, the parameter of energy storage capacity is studied quantitatively and employed as the objective of optimization in order to consider these changes in LHTESS. Finally the results indicate that considering this parameter and optimizing the LHTESS shape based on the interaction of this parameter and solidification acceleration leads to efficient design. This is proposed as the novelty of present study. Other major results indicate that immersing fin in LHTESS enhances solidification rate significantly higher than nanoparticles dispersion. (C) 2017 Elsevier Ltd. All rights reserved.