分形多孔材料的一种改进化气体扩散分形模型

An improved gas diffusivity fractal model for fractal porous materials

基于分形理论与技术,提出了气体在由一簇弯弯曲曲、横截面积大小不等的椭圆形毛细管组成的多孔材料中的气体扩散率分形模型。研究结果表明:归一化气体扩散率是最大孔隙面积、最小与最大孔隙面积之比、多孔材料总横截面积、形状因子及分形维数等多孔材料微结构参数的函数;模型能清楚地揭示影响气体扩散率的物理机制。文中气体扩散率分形模型与已有的实验数据进行对比,结果显示它们之间吻合较好;提出的改进化气体扩散分形模型更具有一般性。

Based on fractal theory and technology,a gas diffusivity fractal model in porous materials which are composed of a bundle of tortuous elliptical capillaries with different cross-sectional areas was presented in this paper. The result shows that the normalized gas diffusivity for porous materials can be expressed as a function of the maximum pore area,the ratio of the minimum pore area to the maximum pore area,the shape factor,fractal dimension and other porous material microstructure parameters. Each parameter has clear physical meaning. The gas diffusivity fractal model can reveal the physical mechanism for gas diffusion in porous materials. The predictions from the gas diffusivity fractal model are also compared with the available experimental data,and a good agreement between them is found. The improved gas diffusivity fractal model has general characteristics.