Detailed numerical analysis of heat transfer enhancement in horizontal shell-and-tube-type n-eicosane-based latent thermal energy storage system

Abstract

A numerical analysis is conducted for both the outward and inward phase change (melting/solidification) processes in a horizontal shell-and-tube-type latent thermal energy storage (LTES) system filled with an n-eicosane phase change material. The analysis includes—for the first time—direct comparisons of the effects of heat transfer enhancement (HTE) methods on the solidification and melting processes, considering five parameters (with three levels for each) and at four phase change stages (70 %, 80 %, 90 %, and 100 %). The HTE, defined by the reduction in the overall phase change time, was found to differ between melting and solidification. In certain situations, the HTE method induces a smaller improvement in melting but a significant deterioration in solidification. The solidification-to-melting-time ratios (SMTRs) for all analysis cases are compared to clearly identify the common HTE methods between the melting and solidification processes. Maximal SMTR values of 11 and 10.85 (corresponding to the worst cases) were observed at the maximal tube eccentricity during the outward phase change and at the maximal tube diameter during the inward phase change, respectively. This research should aid engineers in designing novel technologies capable of efficiently and safely storing thermal energy.