多相复合表面对溶质弥散过程的调控机理研究

Solute or nanoparticle dispersion process plays an important role in energy and chemical engineering fields. Oil-infused surfaces in soil or oil reservoir, man-made superhydrophobic surfaces, slippery liquid-infused porous surfaces inspired by biomaterials all are multiphase composite surfaces. The influence of the surface characteristic on the solute dispersion process is unclear. Previous research demonstrates that: (1) the slip flow near channel's surfaces results in a different solute dispersion behavior from conventional solute dispersion behavior; (2) Periodic distributed slip and no-slip flow boundary conditions are observed near multiphase composite surfaces, such as the superhydrophobic surfaces. Hence, we infer that the flow behavior near multiphase composite surfaces is different from conventional flow behavior near no-slip solid surfaces and totally slip flow behavior, and accordingly results in a different solute dispersion behavior. In this proposal, we plan to fabricate microchannels with multiphase composite surfaces, and reveal the mechanism of solute dispersion behavior according to the fluorescein dispersion experiment and the volume averaging method based model. The research will provide new physical insights into the solute dispersion behavior and provide a new method to control the solute dispersion behavior so that improve the design of industrial processes and devices.

溶质或纳米颗粒的弥散过程在能源、化工过程中起重要作用。土壤或油藏中的含油多孔表面、仿照生物材料制造的超疏水表面、含润滑液的表面均是多相复合表面。多相复合表面性质对溶质弥散过程的影响机理不明。现有理论研究结果表明（1）通道壁面滑移流动使得溶质弥散行为显著偏离常规溶质弥散行为；（2）超疏水表面等多相复合表面会形成周期性滑移-无滑移流动边界条件。因此，申请者推测多相复合表面处流体的流动特征既不同于无滑移流动也有别于完全滑移流动，进而导致独特的弥散行为。本项目拟制备具有多相复合表面的微通道芯片，应用荧光检测技术及体积平均理论模型，揭示溶质弥散行为规律。此研究将深化对溶质弥散行为的理解并为调控弥散行为改善工艺过程及设备设计提供新思路。

化学组分在多孔材料以及复杂微纳表面的扩散、吸附以及宏观流体流动作用下的传递广泛存在于能源、化工、环境等领域。描述此类传递过程的关键宏观参数是弥散系数与有效扩散系数。本项目开发的基于体积平均理论的数学模型可以建立起宏观传递参数与微观通道或孔隙结构之间的关系，借助高性能计算能够准确预测其传递行为。本项目针对两类特殊的问题开展了溶质弥散的研究：（1）随机颗粒堆积构成的复杂孔隙内部溶质的弥散过程，结果表明随机分布的孔隙结构对纵向与横向弥散系数的影响满足统计规律，可以采用统一的表达式预测；（2）多种三维规则介孔-微孔材料内溶质的扩散与吸附过程，研究揭示了介孔形貌以及孔隙率对有效扩散系数的影响。在多相体系或者多相构成的表面处，组分的传递受到多相界面形貌以及多相之间相态变化的影响。本项目开发了描述气液相变的数学模型以及一类特殊的气固相变（结霜）过程的数学模型，并通过大量经典问题的模拟验证了数学模型的可靠性。所建立的数学模型均便于与宏观尺度的数值求解软件耦合，便于分析大尺度工业问题。