Three-dimensional pore-scale observation of drying process of porous media
Three-dimensional pore-scale observation of drying process of porous media
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DOI：
10.1016/j.ijheatmasstransfer.2022.123299
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发表时间：
2022-07-30
影响因子：
5.2
通讯作者：
Suekane, Tetsuya
中科院分区：
文献类型：
--
作者：
Nasir, Muhammad;Kaito, Kazuki;Suekane, Tetsuya
利用X射线显微层析成像技术对多孔介质的孔尺度干燥过程进行了全面研究，并对液膜区和侵入前沿进行了表征。我们的发现揭示了饱和度的降低在孔径上是不均匀的。毛细管重排是指由于毛细管压差导致的液相的重组，其驱动液体从大孔向小孔流动。因此，液体饱和度的降低优先发生在较大的孔隙内。在侵入前沿，液体饱和度急剧下降，饱和度范围从1到0.15左右（0.15 < S < 1）。得到的侵入宽度σ（p），其特征的程度的粗糙度和无序的侵入前沿服从逾渗模型的标度律。因此，该区域受到毛细管和重力之间的相互作用的显著限制。然而，随着在多孔介质内观察到更多的多孔连通团簇，从团簇区域（0 < S < 0.15）获得的累积团簇尺寸分布CDF（s）的临界指数τ偏离普适幂律行为。这一结果表明，液膜内的集群区域，其中的粘性力变得可比的毛细管力的存在。我们还发现，总的气液比界面面积的干燥速率没有影响。这一结果提供了新的证据，液膜区是蒸汽饱和。(c)2022爱思唯尔有限公司保留所有权利。
X-ray micro-tomography was used to comprehensively study the pore-scale drying process and characterize the liquid film region and the invasion front. Our finding reveals that the decrease in saturation is not uniform across the pore size. The capillary rearrangement, which refers to the restructuring of the liquid phase due to the capillary pressure difference, drives the liquid to flow from large pores to small pores. As a result, the decrease in liquid saturation occurs preferentially within the larger pores. A sharp decrease in liquid saturation occurred at the invasion front, where saturation ranged from 1 to around 0.15 (0.15 < S < 1) . The obtained invasion width sigma(p) that characterized the extent of roughness and disorder of the invasion front obeyed the scaling law of the percolation model. Therefore, this region is significantly limited by the interaction between capillary and gravity. However, with more multi-pore connected clusters observed within the porous medium, the critical exponent tau of the cumulative cluster size distribution CDF(s) obtained from the cluster region (0 < S < 0.15) deviates from the universal power-law behavior. This result indicates the presence of liquid film within the cluster region, where the viscous force becomes comparable to the capillary force. We also found that the total gas-liquid-specific interfacial area has no effect on the drying rate. This result provides new evidence that the liquid film region is vapor saturated. (c) 2022 Elsevier Ltd. All rights reserved.