Numerical Analysis of Perforated Versus High-Density Annular Fins for Enhanced Transient Melting in Shell-And-Tube Latent Heat Storage

Enhancing the melting rate in latent heat storage (LHTES) systems is critical for improving power density, yet it requires balancing conductive enhancement against convective facilitation a fundamental trade-off in finned heat exchanger design. This study presents a focused numerical investigation that quantifies this trade-off by comparing two advanced fin configurations for a vertical shell-and-tube LHS unit: perforated annular fins designed to promote natural convection versus high-density solid fins maximizing conductive surface area. Three-dimensional transient simulations using the enthalpy-porosity approach in ANSYS Fluent are conducted to examine the melting of paraffin wax under diverse heat-transfer-fluid (HTF) conditions. The results show that perforated fins (10 fins) speed up melting by 38.8% compared to regular solid annular fins. This is mostly because the holes in the fins help create vortices, allowing fluids to move more easily. But a high-density fin array (20 solid fins) works better overall, cutting the total melting time by 40.6% compared to the perforated version. This improvement is due to shorter thermal diffusion lengths and longer conductive channels, which outweigh the convective benefits in the end. Parametric analysis indicates that HTF temperature is the most important operational parameter. A 5°C increase in temperature reduces melting time by 21–35%, whereas changes in flow rate yield only small improvements (<8.5%). The study reveals a clear design hierarchy: for the examined vertical geometry, conductive optimization via increased fin density yields larger final performance improvements than convective augmentation via geometric characteristics. under a fixed PCM-volume design constraint, doubling fin count via solid fins yields a greater melting-time reduction than adding perforations to a sparser array, though this comparison does not yet isolate whether the benefit stems from the added material/area or from the conductive mechanism per se; a mass- and area-matched control study (Cases A and B) is required to resolve this and is reported as the immediate next step of this research program .These results give clear instructions for making thermal storage systems that work better and charge faster.