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Thesis Advisor陈家镛
Degree Grantor中国科学院研究生院
Other AbstractThe theoretical prediction of effective diffusivity of gases or liquids in porous particles is practically impossible yet. Part of the reason for this is that the effective diffusivity is a complex function of the pore structure geometry and possibly the properties of diffusion species. In addition diffusion rate might be influenced by the specific interactions between diffusing species and pore walls. In the present work, a comparative study of the diffusion behavior of different diffusing species, including gases, non-electrolytes and electrolytes, in porous pellets prepared in the laboratory & believed to have the same pore structure was carried out. Different methods in measuring gas effective diffusivities, namely, the steady state method, the dynamic pulse response method including the square & step ulse response method, were investigated. The experimental results indicate that no significant difference between the steady state and dynamic response methods was observed. The average deviation of the dynamic response results from the values obtained by the steady state method is less than 15%. From the measured values of effective diffusivities, tortuosity factors were calculated with both ordinary diffusion & Knudson diffusion considered using either the average pore radius or the pore size distribution. The tortuosity factors estimated by these two approaches differ appreciably. It is preferable to characterize the structure of a porous particle by the pore size distribution. Different gas pairs, hydrogen in nitrogen or in argon, and nitrogen or argon in hydrogen, were studied as diffusion systems. The tortuosity factors for different diffusion species in the pellets (with porosities from 0.234 to 0.632) were compared. It is quite right to say that the tortuosity factors for gas diffusion are only slightly dependent on the properties of diffusing species and as reported in the literature strongly dependent on the porosities of the pellets.
Document Type学位论文
Recommended Citation
GB/T 7714
陈宇飞. 气体、溶液中的非电解质与电解质在多孔颗粒内扩散的对比研究[D]. 中国科学院研究生院,1989.
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气体、溶液中的非电解质与电解质在多孔颗粒(5412KB) 限制开放CC BY-NC-SAApplication Full Text
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