中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
Vol. 19 No. 3 June 2009 |
Mg-3Ni-2MnO2 nanocomposite powder reaction bed
(School of Materials Science and Engineering, Harbin Institute of Technology (Weihai), Weihai 264209, China)
Abstract:Hydrided Mg-3Ni-2MnO2 composite powders were fabricated by reactive ball milling with hydrogen, and accumulative hydrogenation kinetics and temperature field of reaction bed with various porosities (0.37, 0.53 and 0.63) were measured. The results show that the accumulative hydrogenation kinetics of Mg-3Ni-2MnO2 powder reaction bed depends strongly on the effect of heat transfer, mass transfer and intrinsic reaction together. The reaction bed with the porosity of 0.53 exhibits the largest hydrogenation rate. During the hydrogenation process, the temperature of reaction bed rises quickly due to the fast release of heat, and the temperature difference between center and wall with 0.53 porosity can keep high even for a long time, which promotes fast heat transfer. The further analysis indicates that more emphases should be put on heat transfer rate rather than the only improvement of the effective thermal conductivity.
Key words: hydrogen storage materials; porosity; heat transfer rate; reaction bed