Simulation of hydrogen absorption/desorption on metal hydride LaNi5-H2: Mass and heat transfer

The present study aimed at stimulating the absorption/desorption of hydrogen on LaNi5-H2 metal hydride with special emphasis on the mass and heat transfer during these processes. The numerical simulations have been conducted for reactors with different internal sections. The mathematical model was validated through comparison with the experimental results of Muthukumar et al. [P. Muthukumar, A. Satheesh, U. Madhavakrishna, A. Dewan, Numerical investigation of coupled heat and mass transfer during desorption of hydrogen in metal hydride beds, Energy Convers. Manag. 50 (2009) 69-75]. The spatial and temporal profiles of temperature and concentration were determined and the effect of thermal conductivity of the metal on the heat transfer was clarified. It was found that the storage of H2 was a fast exothermic process that generates rapid elevation of the metal hydride temperature. The metal temperature was much higher within the thin layer near the internal tube of hydrogen feed. Increasing the thermal conductivity of the metal, even has not an effect on the storage capacity, facilitates the rapid returning of the system to the equilibrium state after the complete filling of the material. The capacity of hydrogen absorption/desorption increased proportionally with the thickness of the metal (i.e. decreasing the internal section of the reactor).