Effect of Fin Length and Angle on the Melting Process of Phase Change Materials in Vertical Latent Heat Storage Unit

Abstract

Installing fins is an effective way to solve the poor thermal conductivity of phase change material (PCM) in latent heat thermal energy storage (LHTES) system. This paper aims to research the combined effects of unequal length distribution and the inclination angle of fins on the performance of LHTES system during the charging process. Numerical models are established and verified, then diverse fin structure cases are simulated via analyzing the full melting time of PCM. The characteristics of the melting process are further studied between four representative cases, including the full melting time, melt fraction evolution, average maximum velocity, streamlines contours, temperature uniformity and average Nusselt number. Results show that a 49.8% reduction in complete melting time of PCM is achieved for the optimum case with unequal length and downward annular fins compared to the benchmark case with ordinary annular fin. Besides, optimum case increases the largest average maximum velocity of PCM by 30%, more uniform temperature distribution and larger Nusselt number are obtained.

Keywords: Latent heat thermal energy storage, Phase change material, Unequal length design, Angled fins, Melting time