Comparative study on heat transfer enhancement of metal foam and fins in a shell-and-tube latent heat thermal energy storage unit

ABSTRACT: Metal foam and fins are two popular structures that are employed to enhance the heat transfer of phase change materials in shell-and-tube heat storage units. However, it remains unclear which structure is better in terms of energy storage performance. In this study, the heat transfer enhancement performances of metal foam and fins are compared to provide guidance on the optimal structure to be chosen for practical applications. Three fin structures (four fins, two vertical fins, and two horizontal fins) are considered. Under the full configuration (volume fraction of metal = 3%), the unit with four fins was found to have a faster melting rate than those with vertical or horizontal fins. In other words, increasing the number of fins helps to accelerate the melting process. Nevertheless, the unit with metal foam enhancement has the highest melting rate. Under the half configuration (volume fraction of metal = 1.5%), the melting rate of the unit enhanced by metal foam is significantly decreased, whereas there is no remarkable changes in the units enhanced by fins. However, metal foam is still shown to be the best thermal enhancer. The energy storage rate of the unit enhanced by metal foam can be up to 10 times higher than that of the unit enhanced by fins.