EFFECTIVE DIFFUSIVITIES OF GAS DIFFUSION IN POROUS ALUMINAS

Wicke-Kallenbach steady state diffusion experiment of binary and ternary diffusions of ethylene,argon and carbon dioxide were carried out in two kinds of alumina.The flux equations were established based on the dusty-gas model and Stefan-Maxwell equation and used to interpret the experiment data.The effective diffusivities for binary diffusion and pseudo binary effective diffusivities for ternary diffusion were obtained.At the meantime,the basic condition was derived to treat the effective diffusivities as constant for isothermal binary transient diffusion,which is identical with the experiment results.However,for ternary diffusion the pseudo-binary effective diffusivities can not be taken as invariable.In addition,for each alumina there is almost the same tortuosity no matter whether binary or ternary diffusion is,so tortuosity is a parameter that has a close relationship with the structure of porous media.