In-depth Numerical Simulation of the Impact of Wavy Fin Geometric Arrangement on the Melting Front of PCMs

Abstract

The research paper examines how the heat retention capacity (LHTES) of phase change material (PCM) can be improved through the use of wavy fins. A numerical study of wavy finned PCMs was conducted using a transient 2D CFD model of the melting of a PCM, including tracking the interface between the PCM and the surrounding media. The study analyzed the effect of the most important geometrical features, including wave height, wavelength and distance between fins, on how the rate of melting changed and natural convection currents developed. The results of this numerical study demonstrated that wavy fins offered better performance than straight fins by reducing the thermal boundary layer at the wave troughs and generating secondary flow patterns (Dean vortices) at those elevation points. This analysis showed that, for the optimal configuration of moderate wave amplitude and spacing, total melting time of the PCM was reduced by ~26.6% compared to straight fin configurations. However, the study presents a hydrodynamic boundary condition, beyond which too much fin spacing reduction or too high wave amplitude will create convective choking conditions and develop stagnation regions, which will impede the buoyancy generated flow and lower thermal performance of the system in the final stages of melting. These results will be useful in developing design criteria for the purpose of optimizing the geometric topology of extended surfaces so that they can achieve maximum heat transfer efficiency for use in Energy Storage Applications that utilize PCM