The Stress Developed on the Side Wall of the Pressure Vessel for the Packed Bed of the Hydrogen Storage Alloy and the Change in the Packing State

Abstract

When the hydrogen absorbing alloy was packed in the pressure vessel, the effect of cyclic hydrogen absorption/desorption on the stress developed on the side wall of the vessel and the packing state of the packed bed of the alloy was investigated. The effect of the change in the packing state of the packed bed on the stress was also investigated. While the stress developed on the side wall of the vessel of the packed bed was not observed in the upper region of the vessel, the stress increased with the increase in the number of hydrogen absorption/desorption cycles and showed constant value in the lower region of the vessel. Also, with the increase in the number of cycles, the local packing fraction of the packed bed decreased in the upper region whereas the fraction rose to around 0.7 and then showed a constant value in the lower region. Furthermore, it was suggested that the stress becomes higher in the region with the higher local packing fraction and for the larger number of the cycles even though the fraction is the same. It was also suggested that the local packing fraction becomes a constant value after about 20 cycles of hydrogen absorption/desorption.

Pressure cells for in situ neutron total scattering: time and real-space resolution during deuterium absorption

“…The powder sample was inserted into an open and thin-walled ex situ vanadium container and then sealed into the thick-walled in situ container to form a double structure. A typical hydrogen storage metal/alloy will expand in volume by about 30% due to hydrogen absorption, generating tens of megapascals of stress on the inner walls of the vessel (Okumura et al, 2021). Therefore, sample-derived stresses must be considered in addition to the high-pressure gas.…”

Hydrogen storage kinetics and thermodynamics of Mg‐based alloys by rare earth doping and Ni substitution

“…Alloying is an effective method to improve the thermodynamics and kinetics of Mg‐based hydrogen storage materials. Mainly, by adding alloying elements, new phase structures are introduced into the alloy organization, which improves the thermodynamics and kinetics of hydrogen absorption and desorption of the alloy 9,10 . In addition, a rational preparation process can have an impact on the microstructure of the alloy.…”

“…Mainly, by adding alloying elements, new phase structures are introduced into the alloy organization, which improves the thermodynamics and kinetics of hydrogen absorption and desorption of the alloy. 9,10 In addition, a rational preparation process can have an impact on the microstructure of the alloy. For example, nanocrystals/amorphous crystals, crystal defects, microporosity and cracks produced during the preparation process can help to improve the hydrogen storage properties of the alloy.…”