Bio-inspired fins and obround shell geometry for enhanced shell-and-tube latent heat storage: An experimental and numerical study

Latent heat storage (LHS) systems are essential for advancing low-emission, high-efficiency energy technologies. However, the low thermal conductivity of phase change materials (PCMs) limits their performance, motivating the development of effective heat-transfer enhancement strategies. This study evaluates the synergistic influence of fin configuration and shell geometry on the melting efficiency and heat transfer characteristics of shell-and-tube LHS units. Six shell-and-tube heat exchangers (HXs) with rectangular and bio-inspired fins, each with constant fin and PCM volume, were fabricated using obround and circular shells. Experimental and numerical analyses were conducted to evaluate key thermal performance metrics. The findings revealed that the integration of the tree-shaped fin configuration and the obround shell geometry resulted in the most pronounced enhancement in melting performance and heat transfer rate. Compared to conventional rectangular fins, tree-shaped fins reduced the melting time by 13 % and 10 % in the obround and circular shells, respectively, and increased the time-averaged heat transfer rates by 12 % and 10 %. Modifying the shell geometry from circular to obround reduced the melting time by 40 %, 42 %, and 42 % and increased the time-averaged heat-transfer rate by 58 %, 55 %, and 61 % for the rectangular, Y-shaped, and tree-shaped fin configurations, respectively. A further study of fin dimensions showed that reducing fin thickness decreased melting time by up to 74 % in the circular shell and 41 % in the obround shell, both using tree-shaped fin configurations.