Enhanced Solidification in Latent Heat Storage Systems Using Fins and Twisted Tapes

Latent Heat Thermal Energy Storage (LHTES) systems are limited by the low thermal conductivity of Phase Change Materials (PCMs), which restricts heat transfer during charging and discharging. This study numerically explores geometric improvements to enhance solidification in shell-and-tube LHTES units. Eight configurations incorporating fins and twisted-tape inserts were analysed using a transient 3D enthalpy-porosity model in ANSYS Fluent, with stearic acid as the PCM and water as the Heat Transfer Fluid (HTF). Pressure drop analysis revealed that the introduction of inserts increased hydraulic resistance. Straight tape inserts produced the most pronounced penalty, increasing pressure drop by 186–280% relative to the baseline. Twisted tape inserts introduced an additional 32–37% resistance beyond that of straight tapes. Fin-based configurations did not exhibit any hydraulic penalty. Regarding thermal performance, vertical fins provided the greatest improvement, reducing solidification time by 28.5% compared to the baseline. Helical fins performed particularly well within the time range (0–49 min) due to a higher surface-area-to-volume ratio, while horizontal fins showed limited enhancement. The hybrid helical-fin-twisted-tape configuration achieved optimal performance within the time range (0–47 min), reducing solidification time by 17.8% compared with the base case through combined conductive and convective enhancement. Twisted tapes improved solidification by 5.8% via induced swirl flow. These findings provide essential guidelines for designing LHTES systems for renewable energy and waste heat recovery, balancing thermal efficiency and hydraulic performance.