Experimental investigation of the effects of inclination, fin height, and perforation on the thermal performance of a longitudinal finned latent heat thermal energy storage

Longitudinal fins have been proven to be one of the most economical and easiest means to improve the thermal characteristics of latent heat thermal energy storage systems. Currently, most studies on this topic are numerical, and several research questions regarding the effects of angular position, fin height, and perforation remain unanswered. In this paper, we conducted experimental studies on four solid finned tubes of varying fin heights (10, 20, 25, and 30 mm), and three perforated finned tubes with different hole sizes (4, 8, and 12 mm). We also examined four different angular positions (0°, 30°, 60°, and 90°). Angular positions of 0° and 30° showed a high rate of average temperature rise during charging, while it had no substantial effect on discharging. The optimal fin height was found to be 65% of the annulus for the melting process, while the solidification process did not exhibit the optimal fin height. Perforation improved the thermal performance marginally. For the same fin volume, small diameter holes were recommended over large holes, as the perforated fins with hole diameters of 4 mm and 8 mm had reduced the pre-melting time by 12.65% and 3.16%, respectively, compared to solid fins.