(283a) Modeling Hydrogen Transport Into Palladium Hydride With Detailed Surface Reaction Chemistry

Palladium is an important hydrogen storage and separation material that offers high volumetric power density in metal hydride batteries and fuel cells. We present a multiphysics mathematical model of the coupled reactive flow of hydrogen isotopes in a packed palladium hydride bed. An isotope exchange experiment allows study of hydrogen transport independently of the lattice expansion from palladium to palladium hydride. The model considers rates of chemical reactions and mass transport within a hydride bed and incorporates the multistep reaction mechanisms that take place at the metal bulk, surface and gas levels. A novel feature in the chemical reaction model is that it allows accounting for all absorption, adsorption and diffusion activation energies that can be adjusted depending on the state of the metal surface. The simulation results are comparable to measured values. The model is useful in designing an optimal hydride bed operating at a given temperature, hydride particle size and surface condition. Based on the same chemical kinetic model, we also present a gas chromatography model of the exchange process. This model offers a better understanding of the exchange kinetics by exploring the specifics of the flow.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.