A tool for modelling the breathing of hydride powder in its container while cyclically absorbing and desorbing hydrogen

Hydrogen storage in metal compounds has been actively studied as a way to store energy by G. Sandrock (1999) and M. Latroche (2004) [1,2]. But even if the importance of studying the mechanical behaviour of hydride compounds has been shown early in M. Kawamura et al. (1981) [3] there is still a lack of phenomenological or predictive models for handling this difficulty. In this paper, the use of Discrete Element Modelling (DEM) is investigated as a way to improve our understanding of the mechanical behaviour of hydrides absorbing and desorbing hydrogen, which is also called the hydride breathing phenomenon, and to develop better macroscopic models in the future. Starting from elementary mechanical characterisation of the hydride powder, from matrix compaction dedicated to determine the powder compressibility, to rotating drum, dedicated to determine the flowing ability of the powder, the parameters of the Discrete Element Model are adjusted, and the model is then confronted to the results experimentally obtained on a volume of hydride breathing within an instrumented elementary cell. The method is developed on a TiVCr BCC alloy. The simulations are consistent with experimental results, and have thus been used for a parametric study. This study reveals a strong impact of the slenderness ratio of the hydride powder bed and the particle shape on both powder volume variations and stress variations during the cyclic absorption and desorption of hydrogen. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.