Optimum spacing between horizontal metal hydride (MH) hydrogen storage tanks integrated with fuel cell power system in natural convection

Present investigation examines the ability of metal hydride storage systems to supply hydrogen to a fuel cell,when the metal hydride tanks are heated by natural convection. to determine optimum spacing of horizontal mh tanks in desorption process,theoretical and numerical analysis is presented to compare different storage tank configurations. three configurations are analyzed: storage cases with h/d=3,5 and 10 (array height h,cylinder diameter d). each of the three configuration had different number of cylinders in the array depending on the h/d and spacing between the cylinders. as mh alloys,ab5 type alloy (lani5) is selected. the analysis takes into account the effect of external natural convection heat transfer and reaction kinetics of mh. the spacing is calculated by maximizing the heat transfer by means of accurate correlations. the results of this study reveal that there exists a distance between the mh tanks for which the nusselt number is maximum. by increasing h/d or decreasing the rayleigh number,the optimal spacing will increase. moreover by increasing rayleigh numbers optimum spacing will increase more than 20%. these results show the optimum spacing in a given volume increase with the increasing equilibrium pressure and h/d ratio. © 2015 tibtd printed in turkey.