Thermal performance in latent heat thermal energy storage with annular heat source using different shape fins

Abstract

For a latent heat thermal energy storage (LHTES) unit, its heat transfer performance can be significantly enhanced by increasing the fin surface. The LHTES unit with an annular heat source (AHS) is proposed for different shape fins and structural parameters. A corresponding numerical simulation has been conducted. The results show that pipe diameter ratio γ has the greatest influence on the heat transfer power Φ, followed by the outer and inner fin type in the charging and discharging processes. The increase of γ from 0.55 to 0.7 leads to t_c decreasing by 62.65%, the charging power Φ_c increasing by 153.68%, and the wall-average Nusselt number Nu_c in the charging process increasing by 45.47%. Furthermore, an optimal γ of 0.625 is identified for the discharging process, resulting in −29.61%, 38.27%, and 20.2% changes in t_d, the discharging power Φ_d, and the wall-average Nusselt number Nu_d in the discharging process compared to γ of 0.55. Bifurcation angle θ significantly influences t_c and t_d. The optimal θ for the charging process is 60°, reducing t_c by 40.7% compared to that of 180°. For the discharging process, the optimal θ is 90°, reducing t_d by 8.81%. The number of branches n significantly impacts heat transfer by influencing heat conduction. For the charging process, increasing n from 4 to 14 results in −45.39%, 81.78%, and −39.67% changes in t_c, Φ_c, and Nu_c, respectively, while during the discharging process, it leads to changes of −31.91%, 45.48%, and −25.91% in t_d, Φ_d, and Nu_d, respectively.