Analysis of phase change material (PCM) melting utilizing environmentally friendly nanofluids in a double tube with spiral fins: A numerical study

Abstract

Phase Change Materials (PCMs) show great potential for thermal energy storage applications due to their substantial latent heat release during the transition from solid to liquid phases. The objective of this numerical study is to assess the melting process of a phase change material (PCM) within a vertical helical coil designed as a latent heat storage system. Innovative enhancements to the system's performance are introduced through the utilization of environmentally friendly nanofluids, BH (Biogenic Hierarchical)–SiO2/water and OLE (Olive Leaf Extract)–TiO2/water, and three distinct configurations of spiral fins. A three-dimensional model is implemented to investigate the impact of the number of fins, nanoparticle concentration, initial temperature and velocity of the Heat Transfer Fluid (HTF), as well as various fin thicknesses. The porous enthalpy method within ANSYS-Fluent is employed to model the phase-changing process. The results indicate a significant reduction of 66.88 % in the melting time of solid PCM with the inclusion of three spiral fins compared to the configuration without fins. Furthermore, the thermal performance of BH–SiO2 is found to surpass that of OLE–TiO2, attributed to its higher thermal conductivity. Additionally, the analysis reveals that the melting time is more sensitive to the initial temperature of the HTF than its velocity.