Evaluation of different melting performance enhancement structures in a shell-and-tube latent heat thermal energy storage system

Abstract

Latent heat thermal energy storage employing phase change materials is widely used in energy storage systems. To further improve the low thermal conductivity of phase change materials in these systems, it is essential to investigate different thermal enhancement techniques. In this work, two principal thermal enhancement techniques (i.e., finned tubes and conductive metal foams) are numerically investigated for melting processes in a shell-and-tube latent heat thermal energy storage system. Topology optimised structures are used as fins, and the simulation predictions are validated by experimental results using additive manufactured topology optimised fins. For metal foams, different filling ratios (i.e., whole-foam structure and half-foam structure) are considered. Compared to the configuration without enhancement, the thermal energy storage rates are 3.3–5.8 times higher. In addition, the results show that the topology optimised fins can achieve the best performance, but can only be an economical solution when the unit price ratio between the enhancement technique and the phase change materials is less than 6. For the first time, the thermal enhancement performance and economic efficiency of these two principal techniques are quantitatively analysed. The results would be useful for appropriate energy storage design solutions in practice.