Thermal performance assessment of a thermal energy storage tank: effect of aspect ratio and tilted angle

Latent heat thermal energy storage is essential for a broad range of multidisciplinary thermal applications, due to its capability of keeping a relative constant temperature during thermal energy storage/release. The aspect ratio (AR) and installation angle (tilted angle) for a latent heat energy storage tank play important roles in addressing the issue of thermal energy storage/release efficiency. In this work, the coupled effects of tank aspect ratio and tilted angle upon melting phase change were both experimentally and numerically investigated. Wide range of tank aspect ratios from 0.1 to 8.0 was studied with respect to four representative tilted angles (0°, 30°, 60°, and 90°). The detailed features of melting front propagation, temperature distribution, and free convection development in the melt phase were quantified. Results indicated that melting heat transfer was markedly affected by the tilted angle, regardless of tank aspect ratio. However, the fastest melting occurred at different tilted angles, if different tank aspect ratios were considered. With AR < 1.0, the highest melting rate was found at 0° inclination. As for AR > 2.0, the fastest melting was achieved at an inclination of 60°.