Enhancement effect of T-shaped fins on phase change material melting in a horizontal shell-and-tube storage unit.

• T-shaped fin can enhance heat conduction and convection of PCM at the bottom region. • The horizontally and vertically arranged T-shaped fins outperforms other designs. • T-shaped fins reduce about 1/3 of melting time regardless of HTF temperature and fin volume. • A length ratio of vertical to horizontal portion greater than 1.0 can better enhance the melting performance. Enhancing the melting performance of phase change material (PCM) has always been an important issue in thermal energy storage. T-shaped fin has the potential to enhance melting as it has much larger heat transfer surface away from heat source compared to traditional longitudinal plate fin. However, its enhancement performance remains unexamined. This study examined the effect of T-shaped fins on PCM melting in a horizontal shell-and-tube storage unit. The melting enhancement performance of four T-shaped fins was compared with that of eight longitudinal plate fins which have the same total fin volume with T-shaped fins. The results showed that T-shaped fins can significantly enhance the melting process by shortening the complete melting time and improving the melting uniformity regardless of the heat transfer fluid (HTF) temperature. Compared to longitudinal plate fins, horizontally and vertically arranged T-shaped fins save 34.5% melting time, while the T-shaped fins having a 45° angle with horizontal direction save only 8% melting time. The lengths of the vertical and horizontal portions were further optimized to improve the melting performance. It is found T-shaped fins with a length ratio of vertical to horizontal portion greater than 1.0 can better enhance the melting performance, and a length ratio of 1.33 saves 47.1% melting time compared to the longitudinal plate fins. [ABSTRACT FROM AUTHOR]