Numerical study on the thermal performance of packed-bed latent heat thermal energy storage system with biomimetic alveoli structure capsule

Bionics provides a positive and beneficial impact on the development of various materials and systems, which has been widely used in energy storage, heat transfer enhancement, and solar thermochemical reactions. In this paper, the idea of heat storage unit with biomimetic alveoli structure is proposed and introduced to increase the heat transfer area and improve the thermal performance of the packed-bed latent heat thermal energy storage (LHTES) system. The effects of heat storage unit structure on temperature distribution, liquid fraction, thermal storage capacity, and other performance indexes of the conventional model and biomimetic model are analyzed. The numerical results indicate that the biomimetic alveoli structure can improve the thermal response of heat storage unit, increase the specific surface area, and achieve a faster heat storage process of the packed-bed compared with the conventional structure. Among various existing models, the double-cell model has a significant improvement. Compared with the conventional model, the maximum increase of liquid fraction and charging efficiency are 9.8% and 6.4%, respectively. This study can provide references to optimize packed-bed LHTES and improve its thermal performance under practical conditions.