X-ray micro-tomography and pore network modeling of single-phase fixed-bed reactors
X-ray micro-tomography and pore network modeling of single-phase fixed-bed reactors
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DOI：
10.1016/j.cej.2013.11.077
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发表时间：
2014-03
影响因子：
15.1
通讯作者：
F. Larachi;Rachid Hannaoui;P. Horgue;F. Augier;Y. Haroun;S. Youssef;E. Rosenberg;M. Prat;M. Quintard
中科院分区：
文献类型：
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作者：
F. Larachi;Rachid Hannaoui;P. Horgue;F. Augier;Y. Haroun;S. Youssef;E. Rosenberg;M. Prat;M. Quintard
一个三维（3D）的不规则和非结构化的孔隙网络，建立了使用局部拓扑和几何特性的等距珠包成像的高分辨率X射线计算机微断层扫描技术。孔隙网络模型的开发，以分析三维层流/惯性（非达西）流在介观（孔隙水平）和宏观（整体平均后）水平。非线性层流签名被捕获在中尺度上的收缩和膨胀摩擦损失的类比的基础上。该模型提供了显着良好的预测宏观摩擦损失梯度在达西和非达西制度与明确的分界线，使用基于通道的雷诺数统计。它还能够区分由于孔隙和通道线性损失，以及收缩/膨胀二次损失的贡献。宏观机械分散进行了分析，在回流通道，横向和纵向Péclet数。该模型定性检索Péclet-Reynolds标度律预期的非均质网络的机械分散占主导地位。在水印倡导的是孔隙网络建模的潜力，以建立后构关系的封闭更传统的宏观欧拉方法，以捕捉更现实的单相流动现象，在固定床反应器中的化学工程应用。
A three-dimensional (3D) irregular and unstructured pore network was built using local topological and geometrical properties of an isometric bead pack imaged by means of a high-resolution X-ray computed micro-tomography technique. A pore network model was developed to analyze the 3D laminar/inertial (non-Darcy) flows at the mesoscopic (pore level) and macroscopic (after ensemble-averaging) levels. The non-linear laminar flow signatures were captured at the mesoscale on the basis of analogies with contraction and expansion friction losses. The model provided remarkably good predictions of macroscopic frictional loss gradient in Darcy and non-Darcy regimes with clear-cut demarcation using channel-based Reynolds number statistics. It was also able to differentiate contributions due to pore and channel linear losses, and contraction/expansion quadratic losses. Macroscopic mechanical dispersion was analyzed in terms of retroflow channels, and transverse and longitudinal Péclet numbers. The model qualitatively retrieved the Péclet-Reynolds scaling law expected for heterogeneous networks with predominance of mechanical dispersion. Advocated in watermark is the potential of pore network modeling to builda posterioriconstitutive relations for the closures of the more conventional macroscopic Euler approaches to capture more realistically single-phase flow phenomena in fixed-bed reactor applications in chemical engineering.