Numerical study on the thermal performance analysis of packed-bed latent heat thermal storage system with biomimetic vein hierarchical structure

The vein hierarchical structure has high efficiency of component transportation capacity, it has been widely used in energy storage, solar thermochemical reactions, and photocatalysis. In this paper, the idea of packed-bed latent heat thermal heat storage system (LHTESS) with biomimetic vein hierarchical structure is proposed to improve the heat transfer rate and heat storage efficiency of the packed-bed LHTESS. The size of heat storage unit changes along the axial and radial direction under the same porosity as the conventional uniform structure. The effects of inlet velocity on the completion rate, temperature distribution, pressure drop, and liquid fraction of the conventional structure and biomimetic structure are analyzed. The numerical results indicate that the biomimetic vein hierarchical structure can ameliorate the temperature inhomogeneity, increase the heat transfer area, and improve the thermal response of the packed-bed compared with the conventional uniform structure. The maximum increase of liquid fraction is 25% under different inlet velocities, and the average completion rate of phase change material and system in charge process is increased by 12% and 6%, respectively.