Conjugate heat transfer in anisotropic woven metal fiber-phase change material composite

Latent heat thermal energy storage is an essential technology for addressing the intermittent nature of solar energy, owing to its large energy storage density. However, the low thermal conductivity of phase change material hinders the energy storage efficiency. In the current work, high thermal conductive woven metal fibers are inserted into phase change material to improve its heat transfer rate. The corresponding energy storage process in a latent heat storage unit is investigated, based on pore-scale three-dimensional lattice Boltzmann modeling via numerically reconstructing the fiber morphology. The results indicate that woven metal fibers with optimum porosity should be used to balance the heat transfer capability and energy storage capacity of the woven metal fiber-phase change material composite. In addition, curved woven metal fibers exhibit better thermal performance in a latent heat storage unit than straight woven metal fibers at a high porosity of 0.95. However, straight woven metal fibers are more effective than curved woven metal fibers for enhancing the heat transfer rate of phase change material at a relatively low porosity of 0.90. Importantly, the energy storage rate could be accelerated by 40% through consolidating the anisotropic degree of woven metal fibers with fully unidirectional configuration owing to their enhanced heat transfer in the desired direction. Besides, the heat conduction inside the woven metal fiber-phase change material composite contributes to at least 71.8% of total energy storage amount during conjugate heat transfer, demonstrating its dominant behavior rather than natural convection. Woven metal fibers with designable anisotropic characteristics exhibit evident advantages over isotropic porous media for improving the thermal performance of a latent heat storage unit.