Measurement and simulation of hydrogen storage and thermodynamic properties of LaNi4.7Al0.3 hydride

Abstract

Pressure - Concentration isotherms (PCIs) of LaNi4.7A10.3 hydride was measured using volumetric method at different temperatures. Two important thermodynamic properties viz. reaction enthalpy (ΔH) and entropy (ΔS) were calculated using van't Hoff plot at different hydrogen concentrations. The effect of hydrogen concentration on ΔH and ΔS during hydrogen absorption and desorption was studied. Reaction enthalpy values decreased as the hydrogen concentration increased during both absorption as well as desorption. The variation of reaction enthalpy from start to end of hydrogenation/dehydrogenation was up to 8%. Variation of ΔH was expressed as function of hydrogen concentration by third order polynomial equation. PCIs of this hydride were simulated using Zhou's mathematical model. The input variables for the mathematical model have been taken from experimental data. Few important physical parameters like activity coefficient 'γ', heat of solution 'ΔHs', partial molar volume 'VH', variation rate 'k', 'ΔH', 'ΔS' and slope factor 'fs' were estimated. The simulated and experimental PCIs are found matching closely.