Melting assessment on the effect of nonuniform Y-shaped fin upon solid–liquid phase change in a thermal storage tank

This study provides an alternative solution to the improvement on solid–liquid phase change by designing a Y-shaped fin in a nonuniform pattern along the gravity direction. A numerical model is established and validated through the present measurement and data in literature. Six cases with different Y-shaped fins and locations are designed and compared to the original straight fin case. Thermal assessments on the melting fraction, temperature field, velocity distribution, and uniformity for melting are made. Results demonstrate that the nonuniform melting features caused by the local natural convection are significantly eliminated by the novel nonuniform fin structure. The time required for melting the lower PCM is found to occupy more than 50% of the completely melting time. The accurate local heat transfer enhancement measures (bottom enhancement) are conducive to markedly reduce the full melting time by 21.5%, compared to the uniform fin pattern. Upon using finned thermal storage tank for a mobilized thermal storage truck (bare tube tank), the initial investment increases by 44.9% but the profit increases by 393.6% and the payback period reduces by 69.2%. The use of fin tube in heat storage tank can quickly obtain higher returns based on a small increase in initial investment. This work provides new insights into the understandings of the transient phase change process and the strategies for guiding the design for thermal energy storage tank.