Hydride breathing and its consequence on stresses applied to containers: A review

Abstract This review addresses the hydride swelling and shrinking phenomenon, named hydride breathing, when absorbing and desorbing hydrogen. Two aspects are particularly examined: the evolution of the powder bed volume during cycling, and the stress applied to containers by the hydride bed. Vertical and horizontal containers are distinguished. The literature on the subject is not very exhaustive. Consequently, this article makes a rather complete review of it. It reveals quite heterogeneous behavior between different hydrides, and different types of evolutions can be observed during cycling. Concerning the evolution of the powder bed volume under low loading, a wide range of solid fraction is noted. Concerning the stress applied to containers, the behavior is particularly influenced by two factors: the slenderness ratio and the solid fraction. Results are mapped according to these factors. There seem to be a critical value for the slenderness ratio around 1, but it is difficult to give a universal critical value for the solid fraction. Modelling attempts are also exposed. Some comfort these conclusions, but no model is sufficiently predictable for a use in dimensioning hydride tank. The review finishes with empirical and practical recommendations for a safe design of hydrides containers.