Multicomponent gas diffusion in nonuniform tubes
Multicomponent gas diffusion in nonuniform tubes
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DOI：
10.1002/aic.14711
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发表时间：
2015-04
期刊：
影响因子：
3.7
通讯作者：
T. Veltzke;L. Kiewidt;J. Thöming
中科院分区：
文献类型：
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作者：
T. Veltzke;L. Kiewidt;J. Thöming
在许多技术过程中，气体的多组分扩散发生在很少在其长轴方向上均匀的约束中（例如，催化剂孔隙）。在这里，我们证明了在锥形管中多组分扩散受到阻碍。这种影响随着进口与出口锥半径的比例Λ而增加，与管的方向无关。基于Maxwell-Stefan方程，给出了理想多组分扩散在微锥形管道中的预测解析解。在均匀管上的双球扩散实验中，重现了Duncan和Toor（1962）的结果。模型与实验结果的比较表明，本文提出的解决方案可以可靠地定量预测H2、N2和co2浓度的时间变化，无论管的几何形状是均匀的还是略呈锥形的。在演示的情况下（Λ = 3.16），质量扩散延迟68%。因此，对于气体在“真实的”、典型的锥形孔隙中的扩散，输运限制比目前所考虑的更为严重。©2014美国化学工程师学会学报，61:1404-1412,2015
In many technical processes gas, multicomponent diffusion takes place in confinements that are rarely uniform in direction of their long axis (e.g., catalysts pores). Here, we show that in conical tubes multicomponent diffusion is hindered. This effect increases with ratio of inlet to outlet cone radius Λ, indifferent of the orientation of the tube. Based on the Maxwell–Stefan equations, predictive analytical solution for ideal multicomponent diffusion in slightly tapered ducts is developed. In two-bulb diffusion experiments on a uniform tube, the results of Duncan and Toor (1962) were reproduced. Comparison of model and experiment shows that the solution presented here provides a reliable quantitative prediction of the temporal change of H2, N2, and CO2-concentration for both tube geometries, uniform and slightly conical. In the demonstrated case (Λ = 3.16), mass diffusion is 68% delayed. Thus, for gaseous diffusion in “real,” typically tapered pores the transport limitation is more serious than considered so far. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1404–1412, 2015