Analysis of energy and exergy of eutectic phase change material solidification for various configuration-based triplex tube

Abstract

This study delves into the energy and exergy analysis of eutectic PCM solidification within a triplex tube latent heat storage unit featuring inner tubes of triangular, pentagonal, square, and circular configurations, analyzed numerically. Results encompassing the impacts of mean temperature, solidification temperature, melting fraction, exergetic efficiency, exergy destruction, heat transfer rate, entropy generation number, and system efficiency on solidification time are presented and compared using contour maps and figures. The research also scrutinizes the effects of Fourier numbers on Stefan, Rayleigh, and Nusselt numbers for TES systems based on inner configurations. Past studies primarily concentrated on cylindrical shapes for all three tubes within triplex-tube heat exchangers, disregarding varied internal tube configurations. This investigation introduces novelty by investigating diverse innermost tube geometries (triangular, square, pentagonal, circular) within a triplex tube heat exchanger. The tangible advantages encompass enhanced thermal efficiency relevant to industries such as oil and gas, chemical processing, food and beverage, and power generation. The inner triangular triplex tube thermal energy storage (TES) system exhibits superior performance over pentagonal topologies, boasting stronger Stefan and Rayleigh numbers by 22.52% and 22.86%, respectively, at Fo = 0.0023. Eutectic PCM solidifies 50%, 65%, and 66% faster within triangular configurations than the triplex tube's pentagonal, square, and circular interiors.However, the pentagonal inner tube topology outperforms the triangular one by 13.36 % at a solidification time of 300 seconds. Eutectic PCM solidifies faster in triangular TTTES systems due to their 0.3%, 1.02%, and 1.10% lower heat transfer temperatures than pentagonal, square, and circular systems. Furthermore, in 1800 seconds of solidification, the triangular inner tube discharges 20.16%, 4.92%, and 3.37% more than pentagonal, square, and circular TES systems. Pentagonal, square, and circular inner tube topologies are 13.36%, 3.01%, and 3.84% less efficient than triangular TTTES systems. TES systems with triangular shapes achieve rapid solidification of eutectic PCM at 305.24K, establishing their efficiency over pentagonal, square, and circular configurations.