Numerical investigation of a snail-shaped fin geometry for enhanced heat transfer in shell-and-tube latent heat storage systems

Low thermal conductivity remains a primary barrier to the efficiency of paraffin-based latent heat storage (LHS) systems, necessitating geometry-based heat transfer enhancements. This research proposes a novel snail-shaped fin specifically engineered to augment conduction while maintaining the integrity of buoyancy-driven natural convection pathways. Through a validated numerical investigation of fin length, joint orientation, and multiplication, the study demonstrates that performance enhancement is primarily driven by the strategic activation of thermal dead zones in the lower shell region, where fluid motion is inherently weak. The results establish that while a 50% fin length at a 135° orientation is the most effective for pure charging, reducing melting time by approximately 54%, a comprehensive trade-off analysis identifies the 75% fin length as the superior overall design. This optimized configuration offers a more balanced cycle by significantly accelerating solidification (approximately 21% improvement) with only a marginal penalty to melting efficiency. Furthermore, the study identifies a point of diminishing returns in fin multiplication; although adding up to three fins can reduce melting time by approximately 71%, excessive conductive paths eventually suppress the beneficial fluid circulation essential for thermal homogenization. This work shifts the design paradigm from simple surface area expansion to the spatial optimization of thermal paths, providing a practical, high-efficiency solution.