Analysis of the Two-Stage Phenomenon and Construction of the Theoretical Model for Metal Hydride Reactors †

The metal hydride (MH) reactor serves as the core unit of hydrogen storage systems, with its reaction performance limited by heat transfer rates. Effective enhancement of reactor heat transfer performance can only be achieved through a fundamental understanding of the reactor’s hydrogen–thermal coupling mechanism. The reaction process within the reactor typically exhibits two distinct stages, a characteristic frequently disregarded in previous theoretical models. Through numerical simulation and analysis, the two-stage phenomenon and its associated hydrogen–thermal coupling mechanism were first quantitatively investigated. Based on the assumptions of neglecting the first-stage reaction time and maintaining bed thermal equilibrium, a novel two-stage theoretical model (a quantitative analytical model) was developed. This model successfully characterizes the internal hydrogen–thermal coupling and reaction progress. Having been numerically validated, the new model achieves a prediction accuracy of 2% for reaction rates, significantly outperforming the original reaction front model’s 25.5% error margin.