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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
陈宇飞
Subtype博士
Thesis Advisor陈家镛
1989-06-30
Degree Grantor中国科学院研究生院
Abstract为探明孔隙结构,扩散组分特性以及由这两者决定的扩散机理和扩散组分与孔壁之间的相互作用对有效扩散系数的影响,本文选定气体、溶液中的非电解质和电解质这三类性质相差较大的体系在相同的多孔颗粒内的扩散进行对比研究,目的在于阐明有效扩散系数,特别是曲折因子对孔隙结构和扩散组分特性等因素的依赖关系,为有效扩散系数的估算和预测打下基础。考察由模拟浸取化学反应得出曲折因子的反常高数值是否正确,对模型拟合值的真伪作出判断。在深入研究电解质溶液中扩散规律的基础上,建立混合电解质溶液在多孔颗粒内扩散的数学模型,对混合电解质在孔隙内的扩散问题提供较为严格的处理方法。
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.
Pages115
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8408
Collection研究所(批量导入)
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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