Experimental and Theoretical Studies of Hydrogen Storage in LaNi_4.4Al_0.3Fe_0.3 Hydride Bed

In this article, the experimental measurements of the absorption/desorption P-C-T isotherms of hydrogen in the LaNi_4.4Fe_0.3Al_0.3 alloy at different temperatures and constant hydrogen pressure have been studied using a numerical model. The mathematics equations of this model contain parameters, such as the two terms, n_α and n_β, representing the numbers of hydrogen atoms per site; N_mα and N_mβ are the receptor sites' densities, and the energetic parameters are P_α and P_β. All these parameters are derived by numerically adjusting the experimental data. The profiles of these parameters during the absorption/desorption process are studied as a function of temperature. Thereafter, we examined the evolution of the internal energy versus temperature, which typically ranges between 138 and 181 kJmol^-1 for the absorption process and between 140 and 179 kJmol^-1 for the desorption process. The evolution of thermodynamic functions with pressure, for example, entropy, Gibbs free energy (G), and internal energy, are determined from the experimental data of the hydrogen absorption and desorption isotherms of the LaNi_4.4A_l0.3F_e0.3 alloy.