Design and operating evaluation of a finned shell-and-tube thermal energy storage unit filled with metal foam

This paper introduced a further heat transfer enhancement technique by inserting porous metal foam into the fin interstitials for a shell-and-tube thermal energy storage unit. The energy charging/discharging were evaluated by means of indicators including complete melting/solidification time, heat transfer coefficient, temperature response and energy storage density. To squarely justify the contribution of fin and metal foam to phase change improvement, smooth tube, finned tube and metal foam tube were examined for comparison, as well. The thermal performance of the four thermal energy storage units were evaluated by numerical models that was validated by comparison with experimental results. Based on the smooth tube, the complete melting/solidification time significantly decreased by 85.83% and 95.83%, and the average heat flux increased by 655.09% and 1834.61%, and the mean Nusselt number greatly increased by 795.93% and 4731.99%, at an inlet velocity of 0.15 m/s for heat transfer fluid. In addition, the charging/discharging capacity of the four thermal energy storage units can be significantly enhanced by increasing the flow rate. The proposed novel finned shell-and-tube thermal energy storage unit filled with metal foam outperformed other competing heat transfer structures, favoring the potentials for further advances in thermal energy storage applications.