Metal hydride beds and hydrogen supply tanks as minitype PEMFC hydrogen sources

In order to improve the properties of hydrogen tanks for hydrogen fuel cells, we studied the effect of two different matrix configurations, one being pellet pressed by Cu coating hydrogen storage alloy powders and the other foam nickel sheets filled with hydrogen storage alloy powders, on the heat and mass transfer properties of metal hydride beds. AB5-type alloy Ml0.85Ca0.15Ni5 and AB2-type alloy Ti0.9Zr0.15Mn1.6Cr0.2V0.2 were used as hydrogen storage materials, respectively. Comparison with general metal hydride powder beds shows that the heat transfer property of the beds with these two new matrix configurations is well improved. Based on these two new matrix configurations of metal hydride beds, hydrogen tanks with different structures and capacities were designed and prepared. For the prototype tanks of 500 l hydrogen storage capacity, the gravimetric and volumetric density of the tanks with AB5-type and AB2-type materials can attain values of the order of 1.1 wt%, 25 kg H2/m3 and 1.3 wt%, 40 kg H2/m3, respectively.