Numerical investigation of coupled heat and mass transfer during desorption of hydrogen in metal hydride beds

This paper presents a numerical investigation of two-dimensional coupled heat and mass transfer processes in MmNi4.6Fe0.4 and MmNi4.6Al0.4 based metal hydride beds of cylindrical configuration during desorption of hydrogen using a commercial software FLUENT 6.1.22. Temperature and concentration profiles at different radial locations, variation of average bed temperature and amount of hydrogen desorbed are presented at different hot fluid temperatures and bed thicknesses ranging from 30 to 50 °C and 5 to 15 mm, respectively. The numerical results show that the dehydriding process for both the alloys depends on the temperature distribution in the metal hydride bed. At a given hot fluid temperature of 50 °C, MmNi4.6Fe0.4 and MmNi4.6Al0.4 desorb the maximum hydrogen of about 1.11 and 1.28 wt%, respectively at the supply conditions of 30 bar and 25 °C. The present computational results are also compared with the experimental data reported in the literature and a good agreement was found between the two.