Investigation of a MgH2 hydrogen storage reactor based on honeycomb matrix for heat transfer enhancement

Magnesium-based hydrogen storage materials are excellent hydrogen storage carriers on account of their abundant resources, low prices and high volumetric storage density. But, in practical applications, they still face problems such as high heat transfer resistance and slow H2 absorption/desorption rate when the material filled in a fixed bed reactor. To enhance the heat transfer process, this paper proposed a honeycomb matrix packed bed based hydrogen storage reactor with optimized structure. Compared to the conventional reactor, the alumina ceramic based honeycomb reactor showed faster heat discharge rate during absorption process, and the average absorption rate increased by 5.6 times within 90 % absorption process. Additionally, the material type and pore structure are key factors affecting the performance of such reactors. The results indicate that the hexagonal pore structure of the matrix has the best heat transfer strengthening effect under the same pore volume ratio, and the average absorption rate increased by 11.0 %, 24.0 % and 44.0 % in comparison with the circular, square and triangular pore structures, respectively. Nonetheless, with the increase of the thermal conductivity of the honeycomb material, such as using copper, the influence of its pore structure on the heat transfer and absorption rate gradually weakens.