Microscale modeling of metal hydride reactors

The main objective of this thesis is to develop a mathematical model at a micro scale for metal hydride reactors. This model consists of the creation, simulation, and validation of a model that improves the thermal conductivity of hydrogen storage materials in metal hydride reactors and enhances their storage capabilities, describing their kinetics. Initially, the copper coating thicknesses of LaNi5 powders used as hydrogen storage material were created using Digimat software in the range of 0.8-1.4 µm, and a three dimensional model was established in COMSOL to simulate their behavior. Subsequently, geometric structures were formed by adding expanded graphite (ENG) to LaNi5 powders at ratios of 1%, 5%, 10%, and 20% using Digimat software, and these structures were solved with the help of COMSOL. The developed micro models, considering the mass conservation of the metal alloy absorbing hydrogen, Darcy flow in a porous medium, and exothermic heat production during hydrogen absorption processes, were formulated, numerically solved, and experimentally verified. The copper coating thickness was optimized at 1.2 µm, and the ENG contribution ratio was optimized at 5%, resulting in approximately a 350% increase in the thermal conductivity of the hydrogen storage material. It was also observed that LaNi5 powders were fully bonded with H2 after the storage processes.