Experimental and theoretical study of compositional inhomogeneities in LaNi5Dx owing to temperature gradients and pressure hysteresis, investigated using spatially resolved in-situ neutron diffraction. (9th March 2017)

• Record Type: Journal Article
• Authors: Mohammadshahi, S.S.; Webb, T.A.; Gray, E.MacA.; Webb, C.J.
• Is Part Of: International journal of hydrogen energy. Volume 42:Number 10(2017)
• Page Start: 6793
• Page End: 6800
• Publication Date: 2017-03-09
• Subjects: In-situ neutron diffraction -- Multiphysics -- Metal hydride -- Compositional inhomogeneities -- Large aliquot effect; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2016.12.061
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: An in-situ neutron investigation of the spatial variation in hydride composition of LaNi5 after a single absorption pressure step was performed. Compositional inhomogeneities are formed due to the strong temperature gradients created by the rapid absorption process coupled with the pressure and temperature hysteresis of the metal–hydrogen interaction. The hydride fraction of LaNi5 in a cylindrical cell was mapped using the ENGIN-X stress/strain instrument and quantitative phase analysis performed using the Rietveld technique. The material was observed to preferentially absorb hydrogen close to the edges of the cell where heat transfer out of the material was more efficient. This spatial variation was maintained even after thermal equilibration. The experimental results are compared to predictions of a 3D multiphysics model solved by the software package COMSOL. The good agreement achieved demonstrates the suitability of this model for optimisation of metal hydride tank systems. Highlights: Spatially-resolved neutron study of LaNi5 absorption. First qualitative mapping of the large aliquot effect. Compositional inhomogeneities in LaNi5 due to temperature gradients and hysteresis. Neutron diffraction results confirm large aliquot effect. Multiphysics model in good agreement with experiment.