Modeling the mechanical behavior of sodium borohydride (NaBH₄) powder

This paper addresses the numeric optimization for NaBH₄ powder flow which is commonly used for hydrogen gas production. During the motion process of the powder, a high number of collisions occur between particles constituting the powder. This paper focuses on modeling and finding the parameters that govern these collisions. We use a discrete element method to model the powder and assume that the powder is composed of tiny spheres interacting according to a specific spring damping model. In a series of appropriate physical wedge penetration experiments, force-displacement graphs were measured. In addition, a set of shear tests were conducted from which normal-shear force graphs were extracted. Analytical estimations were formulated for each of the experiments. These graphs were then compared with graphs generated by corresponding simulation tests. Using Genetic Algorithm optimization we obtained a set of governing parameters that best fits the powder behavior. In order to refine our results we have used our analytical formulations to manually search the parameter space for a better fit. Lastly, an angle of repose test validated our model.