In-depth understanding synergistic characteristics of heat-fluid-mass transport in packed bed with large-size hierarchically porous heat storage module: in-situ experiments and numerical simulations

Modification strategies can significantly enhance the sintering resistance of calcium (Ca)-based materials on a laboratory-scale. However, achieving high thermal storage performance of modified materials in large reactors remains a challenging task due to mismatched heat–fluid–mass transfer, which limits the application of these materials across different scales. In this study, a three-dimensional network of connected flow channels was constructed using a hierarchically porous heat storage module, which facilitated the synergistic transport of heat, fluid, and mass in a large-scale reactor. This study explored the synergistic characteristics and coupling mechanism of heat–fluid–mass transport in the reactor by combining in-situ experiments and numerical simulations. The in-situ experimental findings revealed that the 3D-connected flow channel network improved synergistic transport of heat, mass, and fluid. Compared to the conventional powder packed bed, the average heat release power of the reactor with the packed hierarchically porous heat storage module increased by 479 %. Further, a multi-physical coupling model with modified mechanism function was established based on in-situ experimental data, and the relationship among temperature, gas distribution, and reaction process was clarified. Most importantly, a three-stage synergistic mechanism was uncovered, encompassing intrinsic kinetic control of the material, subsequent device-scale heat–fluid–mass coupling control, and ultimately reverting to the material's diffusion control. In-depth understanding of the three-stage synergistic transition mechanism provides the scientific basis for scale-up thermochemical energy storage reactor design.