A numerical study of dust explosion properties of hydrogen storage alloy materials

Hydrogen as a clean fuel has gained increased attention in the recent years and considerable research is being undertaken to develop hydrogen storage technologies. Hydrogen storage using metal hydride is one such technology. Hydride materials, used in hydrogen storage technologies, in powder form can be an explosion hazard and testing these materials using standard techniques is also difficult. Research reported in this paper is an attempt to develop numerical methods to obtain explosion properties of such materials. In this work a one dimensional transport-type model is presented to simulate the dust explosion process in a closed 20-L spherical vessel. Transport equations for energy, species and particle volume fraction are solved with the finite difference method, whilst velocity distribution and pressure are updated with numerical integration of the continuity equation. The model is first validated with experimental data and then applied to simulate the explosion process of an AB2-type alloy powder used for hydrogen storage. Two kinetic models accounting for the particle burning mechanism are investigated in the current study. One is based on an Arrhenius surface reaction law, the other is based on a simplified diffusion-type d2 law. The former is found to be better in terms of prediction of the deflagration indices. This work is of great significance in safety assessment of new hydrogen storage materials in the processes of their production, storage and transportation.