Theoretical analysis of hydriding reactions of ZrCo and LaNi5 intermetallic alloys using non-isothermal shrinking core model

Abstract

Hydriding reactions of spherical and flat plate geometries of zirconium cobalt (ZrCo) and lanthanum penta-nickel (LaNi₅) intermetallic alloys were studied using kinetic data, and modified shrinking core model to account for concentration and temperature gradients in the gas film and ash layer under pseudo steady state non-isothermal conditions of 300, 310 and 320 K. The volumetric expansion of the alloy particle due to changing density was assumed during the hydriding reactions. The total hydriding time of 10⁹ s was determined by numerical computati-on for different bulk temperatures, hydrogen concentrations and particle sizes; and the rate controlling process was identified to be diffusional. The values of the reaction times were very high, but could serve as data for predicting the length of hydriding cycle during hydrogen storage and recovery.

Keywords: Hydriding reactions, Intermetallic alloys, Hydrogen storage, Shrinking core, Non-linear kinetics