Experimental and numerical studies on the heat transfer improvement of a latent heat storage unit using gradient tree-shaped fins

To improve the thermal performance of horizontal latent heat storage (LHS) units, this study investi-gates two innovative LHS units using uniform and gradient tree-shaped fins. By coupling visualization experiments and three-dimensional numerical simulations, the melting/solidification behavior and ther-mal properties of innovative LHS units are comprehensively analyzed and compared with traditional LHS units. The results show that tree-shaped fins facilitate heat diffusion from point to area, breaking the heat transport hysteresis in traditional LHS units, thus accelerating the melting/solidification rate. During the melting process, the gradient tree-shaped fins strengthen the heat transfer in lower parts of the LHS unit and extend the convective heat transfer duration in upper regions, promoting the synergistic strength-ening of natural convection and heat conduction in the late melting stage. Compared to the uniform fin layout, the gradient tree-shaped fins effectively increase the melting rate, shortens the melting duration by 9%, and further improve the overall temperature uniformity of LHS units. However, the non-uniform transport path of gradient tree-shaped fins is not conducive to solidification heat transfer with conduc-tion as the primary thermal regime, which increases the temperature gradient of LHS units and prolongs the solidification duration by 57.4% compared to the uniform tree-shaped fins. (c) 2021 Elsevier Ltd. All rights reserved.