气体在微孔介质中的等效扩散系数预测  

Prediction of Gas Effective Diffusion Coefficient in Microporous Media

作　　者：何新婷[1] 王沫然[1] 

机构地区：[1]清华大学工程力学系热科学与动力工程教育部重点实验室,北京100084

出　　处：《工程热物理学报》2016年第1期150-154,共5页Journal of Engineering Thermophysics

基　　金：国家自然科学基金项目(No.51176089);教育部博士点基金项目(No.20130002110077)

摘　　要：本文通过数值模拟研究了微孔介质内部结构对气体等效扩散系数的影响。采用随机生成生长方法生成多孔介质的三维微观结构,使用高效的格子-Boltzmann方法求解扩散的控制方程,可预测微孔结构内气体的等效扩散系数。模拟结果表明:微孔材料的内部结构对多孔介质中气体扩散及等效扩散系数有显著影响。对于高孔隙率情况,基于Fick定律数值预测的气体等效扩散系数和实验结果吻合较好;对于部分饱和的颗粒状微孔介质,孔隙内液滴阻碍了气体的扩散路径,多孔介质的无量纲等效扩散系数与饱和度呈非线性关系。This paper presents the structure effects on diffusion in microporous granular media by numerical modeling.Using a random generation-growth method to reproduce the three-dimensional microstructures of granular porous media and a lattice-Boltzmann method to solve governing equations for gas diffusion,we could numerically predict the effective diffusion coefficient of gas in granular porous media.The simulation results indicate that the microstructures of porous media influence the gas diffusion in porous media and the corresponding effective diffusion coefficient significantly.At high porosity regime,the numerical predictions of effective diffusion coefficient based on Fick’s law are in good agreement with experimental data.For partially-saturated granular porous media,the water-filled pores disturb diffusion,resulting in the non-linear relationship between normalized effective diffusion coefficient and the liquid saturation.

关 键 词：微孔介质 等效扩散系数 格子-BOLTZMANN方法 构效关系 

分 类 号：TK123[动力工程及工程热物理—工程热物理]