Pore-scale investigation on nonaqueous phase liquid dissolution and mass transfer in 2D and 3D porous media
Pore-scale investigation on nonaqueous phase liquid dissolution and mass transfer in 2D and 3D porous media
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DOI：
10.1016/j.ijheatmasstransfer.2021.120901
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发表时间：
2021-04
影响因子：
5.2
通讯作者：
Yingxue Hu;Anindityo Patmonoaji;Haiping Xu;Kazuki Kaito;Shintaro Matsushita;T. Suekane
中科院分区：
文献类型：
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作者：
Yingxue Hu;Anindityo Patmonoaji;Haiping Xu;Kazuki Kaito;Shintaro Matsushita;T. Suekane
多孔介质中的流液相间传质在非水相液污染土壤和地下水的修复中起着重要作用。在这项研究中，我们从实验上阐明了多孔介质中的孔尺度溶解过程和宏观相间传质系数。此外，利用无损可视化技术确定了溶解过程中残留相的局部特征，包括饱和度和界面面积。动态溶解过程表明，并不是所有的气泡都同等地暴露在流动的水中，死端的气孔大大降低了溶解速度。根据线性驱动力模型，由剩余饱和度预测了流动水中NAPL的浓度。估算了浓度和界面面积修正后的局部传质系数和总传质系数。结果表明，由于NAPL溶解于水中，流动水中的NAPL浓度沿注水方向增加。局部传质系数沿样品呈均匀分布，表明传质系数与浓度差无关。通过比较二维(2D)微观模型和三维(3D)填充床，研究了孔结构对包埋NAPL溶出过程的影响。在达西流条件下，三维填充床的总传质系数较高。三维填充床与二维微观模型的主要区别在于孔道几何结构的非均质性和孔道连通性的差异。
Fluid–fluid interphase mass transfer in porous media plays an important role in the remediation of soil and groundwater contaminated by nonaqueous phase liquid (NAPL). In this study, we experimentally elucidated the pore-scale dissolution process and the macroscopic interphase mass transfer coefficient inside the porous media. Further, the local characteristics of the residual phase, including saturation and interfacial area, were determined during the dissolution process using nondestructive visualization technologies. The dynamic dissolution process indicated that not all blobs are equally exposed to flowing water and the dead-end pores considerably decreased the dissolution rate. According to the linear driving force model, the NAPL concentration in mobile water was predicted from the residual saturation. Further, the local and overall mass transfer coefficients corrected with concentration and interfacial area were estimated. The results showed that the NAPL concentration in mobile water increased along the water injection direction because of the NAPL dissolved in water. The local mass transfer coefficient exhibited a uniform distribution along the sample, indicating that the mass transfer coefficient is independent of the concentration difference. The effect of pore structure on the dissolution process of entrapped NAPL was studied by comparing a two-dimensional (2D) micromodel and a three-dimensional (3D) packed bed. The overall mass transfer coefficient was higher in the 3D packed bed under Darcy flow conditions. The major differences between the 3D packed bed and 2D micromodel can be attributed to the heterogeneity of pore geometry and the differences in pore connectivity.