Knudsen diffusion - Wikipedia
Knudsen diffusion, named after Martin Knudsen, is a means of diffusion that occurs when the scale length of a system is comparable to or smaller than the mean free path of the particles involved. An example of this is in a long pore with a narrow diameter (2–50 nm) because molecules frequently collide with the pore wall. [ 1 ]
克努森扩散 - 百度百科
判断扩散过程是以Knudsen扩散为主，还是以分子扩散为主，通常有两种方法。 第一种方法是比较DAB和DK的大小。 如果，则过程速率的限制步骤为Knudsen扩散；反之，则为分子扩散。 n－分子的密度，cm -3。 将计算的 与孔径 作比较，如果，则为分子扩散；如果，则为Knudsen扩散。 [1] 式中，A－分子的平均自由程，cm。 该式表明，γ对2a的比值等于分子扩散系数DAB和努森扩散系数DK之比。 由此可以确定在某一扩散过程中，是否可以忽略分子扩散系数式或努森扩散系 …
Knudsen Diffusion - an overview | ScienceDirect Topics
Knudsen diffusion attempts to describe the state of the porous medium being subjected to gas particles motion with Knudsen number exceeding unity. The net flux of a gas species correlating the concentration gradients to diffusive flux is given by
克努森扩散 - 维基百科，自由的百科全书
克努森扩散（Knudsen diffusion）是一种系统的尺度相当或小于其中粒子的平均自由程时发生的一种扩散模式。比如在一个很长的细孔，孔径大约2-50 nm， 这时分子就会频繁地与孔壁发生碰撞。
A generalized Knudsen theory for gas transport with specular and ...
2023年11月15日 · Here we develop a generalized Knudsen theory, which is applicable to various boundary conditions covering from the extreme specular reflection to the complete diffuse reflection. Our model...
什么是Knudsen扩散？ - 知乎专栏
Knudsen数的定义为. Kn=\frac{λ}{d} 式中， λ —— 气体分子的平均自由程 ，μm； d ——孔隙直径，μm。 当 Kn >1时，气体分子之间不产生碰撞，气体分子主要与孔隙壁面碰撞，并沿孔隙向前传质，这就是所谓的Knudsen扩散，它已成了 页岩气 的重要开采机理。
Knudsen Diffusion - SpringerLink
2015年12月19日 · The phenomenon, called Knudsen diffusion, is relevant whenever the distance between molecular collisions is greater than the pore diameter. This interaction can be the governing factor of the diffusion rates.
introduction of models of molecular diffusion in the presence of geometric constraints (e.g., the Knudsen and Fick–Jacobs diffusion); when these constraints are imposed by the solid matrix of a porous medium, the resulting equations provide a pore-scale representation of
Diffusion in Porous Media: Phenomena and Mechanisms
2019年3月18日 · Knudsen and Fick–Jacobs diffusion describe molecular diffusion under confinement. For diffusion in heterogeneous porous media, we distinguish between trap and barrier models, which have distinctly different transport properties.
The Principle of Gas Separation - SpringerLink
2016年1月1日 · In porous membranes the transport of gases is based on the so-called Knudsen diffusion. And in dense solid materials the gas transport is based on a solution-diffusion mechanism. Both the Knudsen diffusion as well as the solution-diffusion transport can result in a selective transport of gases and thus in a separation of gases.
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