In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arre...In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switch devices of surge arresting materials, in general.展开更多
The lack of research on the effect of diffusion on methane extraction leads to low methane concentration and low utilization.The Comsol Multiphysics software is used to solve the numerical gas and solid coupled model ...The lack of research on the effect of diffusion on methane extraction leads to low methane concentration and low utilization.The Comsol Multiphysics software is used to solve the numerical gas and solid coupled model which considers the diffusion of coal matrix,fracture seepage,permeability evolution and coal deformation.The simulation results reveal the effect of diffusion process on methane migration.The gas diffusion rate is relatively high in the initial stage.With the increase in time,the difference between coal fractures and coal matrix blocks becomes lower and the gas diffusion rate decreases gradually.The gas seepage rate decreases significantly near the borehole and the decrease degree becomes small when it is far away from borehole.The influence of diffusion time on gas drainage rate is not obvious.展开更多
文摘In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switch devices of surge arresting materials, in general.
基金This study is sponsored by the National Natural Science Foundation of China(no.51679199)the Initiation Fund of Doctor’s Research(no.107-451117008)+1 种基金the Special Funds for Public Industry Research Projects of the Ministry of Water Resources(no.201501034-04 and 201201053-03)the Key Laboratory for Science and Technology Coordination&Innovation Projects of Shaanxi Province(no.2014SZS15-Z01).References。
文摘The lack of research on the effect of diffusion on methane extraction leads to low methane concentration and low utilization.The Comsol Multiphysics software is used to solve the numerical gas and solid coupled model which considers the diffusion of coal matrix,fracture seepage,permeability evolution and coal deformation.The simulation results reveal the effect of diffusion process on methane migration.The gas diffusion rate is relatively high in the initial stage.With the increase in time,the difference between coal fractures and coal matrix blocks becomes lower and the gas diffusion rate decreases gradually.The gas seepage rate decreases significantly near the borehole and the decrease degree becomes small when it is far away from borehole.The influence of diffusion time on gas drainage rate is not obvious.
