Simulation study on the outlet flow dynamics of a hydride-based hydrogen storage canister for medical use

In recent years, hydrogen molecule as therapeutic antioxidant was found to be useful for the treatment of a number of diseases. To supply hydrogen safely and reliably in the hospital, a patent-pending system was proposed by the authors, including a canister filled with metal hydride, a gas mixing chamber and some other components. The outlet flow of the canister must be controlled within certain accuracy to assure the medical effect of the hydrogen intake, thus was investigated in this work. The mathematical model of hydrogen release process, which couples porous flow, heat and mass transfer was solved using a commercial software package COMSOL Multiphysics 3.5a. The outlet flow dynamics are tested in the cases of convective heating and electrical heating, and great differences are found. For the case of electrical heating that provides constant heat flux, the mass flow rate of H2 showed little temporal variation after the initial transient. Moreover, under certain conditions a PI control strategy was successfully applied to regulate the valve openness for keeping a constant flow rate of H2.