Toward high-performance modular thermochemical energy storage: An engineered biomimetic leaf-vein reactor with simultaneous heat and mass transfer enhancement

The industrialization of packed-bed thermochemical reactors is hindered by challenges such as non-uniform heat and mass transfer and unstable heat flux within the reaction materials. To address these issues, this study proposes a novel modular reactor design inspired by biomimetic leaf-vein channels, aimed at significantly enhancing gas–solid heat and mass transport. The modular enables scalable heat storage capacity and precise adjustment to match varying thermal demands. Using computational fluid dynamics (COMSOL Multiphysics), the heat and mass transport performance of the reactor was evaluated. Structural parameters were optimized via orthogonal design and further extended to tertiary leaf-vein configurations based on dimensionless parameter equivalence. Results indicate that the conventional design is primarily constrained by limited CO₂ mass transfer, where the entropy generation from mass transfer is 2.51 times that from heat transfer. The orthogonally optimized secondary leaf-vein structure reduces carbonation time by 79.83%. The single-outlet tertiary configuration achieves full-domain synchronous reaction within 250 min, improving the uniformity of CO₂ and heat flux distribution by 28.60% and 12.35%, respectively. A dual-outlet layout balances mass transfer resistance in the x- and y-directions, shortening reaction time by 18.70%. The proposed design also exhibits superior performance during the calcination step, reducing completion time by 65.58% compared to the baseline system. In summary, the modular biomimetic leaf-vein reactor offers flexible adaption to different heat loads and enables simultaneous enhancement of both heat storage and release processes, providing a promising new paradigm for engineering CaCO₃/CaO thermochemical energy storage systems.