Papers by Author: Xiao Ming Du

Abstract: Mould filling and solidification of aluminum alloy housing in die casting were simulated by the casting simulation software. Distribution and change of velocity field and temperature field were visualized. The optimized processing parameters were obtained with pouring temperature at 600^°C and pre-heated temperature of mould at 180^°C as well as injected velocity at 2.5m/s. The qualified aluminum alloy housing and the dense microstructure were successfully produced by adopting the optimized processing parameters, which is proved by the actual production.

Abstract: Grand Canonical Monte Carlo(GCMC) method was employed to simulate the adsorption properties of molecular hydrogen on NaA zeolite at 40-293 K and pressures up to 10000 kPa in this paper. The results indicated that the adsorption capacity of hydrogen increased with decreasing temperatures and increasing pressures. The highest hydrogen uptake value is 1.54 wt.% at 40 K and 10000kPa. Adsorption temperature has an important effect on adsorption energies and adsorption sites of hydrogen molecules in NaA zeolite. For lower temperature (below 180 K), the oxygen atoms of zeolite framework and extra-framework cations are stable adsorption sites of hydrogen molecules. For the higher temperatures (above 180 K), the oxygen atoms are only stable adsorption sites of hydrogen molecules.

Abstract: A general model based on Ono-Kondo lattice theory for hydrogen adsorption, nearest neighbor interaction energy among adsorbate molecules were derived according to thermodynamic principle. A linear form of the above general model was applied to determine the interaction energies among hydrogen molecules inside adsorption layer from the previous experimental data of hydrogen adsorption on A- and X-type zeolites. The results show that the energies of hydrogen-hydrogen interactions inside the adsorption layer are negative values, indicating that the attractions among the adsorbed hydrogen molecules are prominent in the present work. And the influence of hydrogen molecules outside adsorption layer on the adsorbed hydrogen molecule is not important.

Abstract: Grand Canonical Monte Carlo (GCMC) method was employed to simulate the adsorption properties of molecular hydrogen on crossing the critical temperature in all-silica ZSM-5 zeolite in this paper. The results indicated that the adsorbed amounts of hydrogen increased with decreasing temperatures and increasing pressures. The highest hydrogen uptake value is 2.24 wt% at 25 K and 10000 kPa. By comparing the variation of the hydrogen adsorption isotherms on crossing the critical temperature, it is shown that the micropore filling and capillary condensation were the main adsorption mechanism under the critical temperature of hydrogen, and the micropore filling was the adsorption mechanism above the critical temperature. The results and data of hydrogen adsorption properties obtained from the simulations are theoretically significant for understanding of the mechanism of hydrogen storage on microporous zeolites.