A three-dimensional hydrogen desorption model is developed to examine the hydrogen desorption process and resulting heat and mass transport phenomena in metal hydride hydrogen storage vessels.  The metal hydride hydrogen desorption model is governed by the conservation of mass, momentum and thermal energy.  Although considerable hydrogen desorption data are available in the literature, model validation has been overlooked in most desorption modeling studies.  Therefore, in the present study, the developed model is first validated against the temperature evolution data measured on a cylindrical LaNi₅ metal hydride vessel. The equilibrium pressure for hydrogen desorption in LaNi₅ is derived as a function of the H/M atomic ratio and temperature based on the experimental data reported in the literature.  In general, the numerical simulations are in good agreement with the experimental data, which confirms the validity and accuracy of the proposed 3D desorption model.  Both the calculated and measured temperature profiles exhibit an initial sharp drop, which is indicative of a relatively rapid hydrogen desorption rate compared to the heat supply rate from the vessel external walls at the early stages.  On the other hand, the effect of heat supply becomes influential at the later stages, leading to a smooth increase in vessel temperature in both the simulation and experiment.  This numerical study provides a fundamental understanding of detailed heat and mass transfer phenomena during the hydrogen desorption process, and suggests that the efficient design of a storage vessel and heating system is essential for achieving rapid hydrogen discharging performance.

presenter : Saad El Dine EL Ferekh