Numerical study of hydrogen purification using metal hydride reactor with aluminium foam

The present paper describes a numerical study of heat and mass transfer processes in a metal hydride reactor for hydrogen purification with aluminium foam. The mathematical model, which was used previously for numerical simulation of heat and mass transfer processes in different types of metal hydride reactors, was modified for a reactor with aluminium foam. To validate the thermal equilibrium between the aluminium foam and metal hydride, pore-scale modelling was performed. In the case of pure hydrogen sorption, the model was validated by a comparison with experimental data; good agreement for sorption dynamics was obtained. The effects of various parameters of the pressure swing absorption method on the effectiveness of metal hydride systems for hydrogen purification were studied. The obtained results show that the use of aluminium foam enhances intensity of heat and mass transfer and consequently decreases the time required for hydrogen purification (up to two times) compared to a case without aluminium foam, while the volumetric capacity of the system is reduced slightly (9%). It is shown that pressure swing absorption method with fixed time interval between purges and the method with fixed interval of the fraction changing of the transformed material between purges provide a similar performance; in the second case the hydrogen recovery ratio remains constant during the hydrogen purification process.