非饱和多孔介质中多相多组分传输过程连续和间断角液膜之间转换及其影响机理

Drying in porous media is a basic process in many natural phenomenon and practical production processes, and plays an important role in the fields of energy, environment, chemical engineering, agriculture and so on. During drying in porous media, liquid films can be found in the corners of solid matrix; there are two types of such corner film, i.e., continuous and discontinuous corner films. The mass and heat transfer in porous media can induce the transition between the continuous and discontinuous corner films. The effects of the continuous and discontinuous corner films on the transport processes in porous media, however, are completely different. Therefore, to uncover the mechanisms of the multiphase and multicomponent transport during drying in porous media, it is necessary to understand in detail the transition between the continuous and discontinuous corner films as well as its impacts on the transport processes. According to the feature of the transprot processes during drying in porous media, this project aims to uncover the mechanism of transition between the continuous and discontinuous corner films as well as its influence during the multiphase and multicomponent transport processes in unsaturated porous media. The coupled relationship will be revealed between the heat transfer, vapor transport, liquid flow, solute transport, menisci movement, gas-liquid phase change, solute crystallization, and transition between the continuous and discontinuous corner films. A pore scale model with the transition between the continuous and discontinuous corner films will be developed for the multiphase and multicomponent transport processes in unsaturated porous media, which will lay a fundation for the development and application of the theory of transport in porous media.

多孔介质蒸发干燥是构成众多自然现象和各种生产与技术的基本过程，在能源、环境、化工、农业等领域有着重要的应用。在多孔介质蒸发干燥过程中，固体骨架拐角处存在角液膜，并根据类型可分为连续和间断角液膜。多孔介质中的热质的传递会造成连续和间断角液膜之间的相互转换。而连续和间断角液膜对多孔介质中传输过程的影响则完全不同。因此，为了揭示多孔介质蒸发干燥过程的多相多组分传输机理，需深入了解连续和间断角液膜之间的转换及其影响。本申请项目针多孔介质蒸发干燥过程的传输的特点，提出研究非饱和多孔介质多相多组分传输过程连续和间断角液膜的之间转换及其影响机理，揭示连续和间断角液膜的形成及转换机理，及其与热量传递、气相传输、液相流动、溶质传递、界面运动、气液转化、溶质结晶过程的相互耦合关系，建立考虑连续和间断角液膜转换的非饱和多孔介质多相多组分传输孔隙尺度模型，为多孔介质传输理论的发展和应用奠定基础。

多孔介质蒸发是构成众多自然现象和各种生产与技术的基本过程，在能源、环境、化工、农业等领域有着重要的应用。在多孔介质蒸发干燥过程中，固体骨架拐角处存在角液膜，并根据类型可分为连续和间断角液膜。多孔介质中热质传递会造成连续和间断角液膜之间的相互转换。而连续和间断角液膜对多孔介质中传输过程的影响则完全不同。因此，为了揭示多孔介质蒸发干燥过程的多相多组分传输机理，需深入了解连续和间断角液膜之间的转换及其影响。.本申请项目提出研究非饱和多孔介质多相多组分传输过程连续和间断角液膜的之间转换及其影响机理，揭示连续和间断角液膜的形成及转换机理，及其与热量传递、气相传输、液相流动、溶质传递、界面运动、气液转化、溶质结晶过程的相互耦合关系，建立考虑连续和间断角液膜转换的非饱和多孔介质多相多组分传输孔隙尺度模型，为多孔介质传输理论的发展和应用奠定基础。基于通过光刻技术在硅片上加工的由不同尺寸矩形截面孔道构成的多孔介质，进行多孔介质蒸发可视化实验。建立了考虑连续和间断角液膜的孔隙网络模型模，并与实验结果进行了对比验证。发现由于固体骨架凸结构造成角液膜打断的毛细剪效应。此外，实验发现在多孔介质的蒸发过程中出现被气相占据的孔隙体重新被剩余液相入侵并被气泡切断形成新的气液构型，该形象称为毛细失稳。提出的孔隙网络模型进一步考虑了毛细失稳现象并与实验结果进行对比验证。对含结晶的多孔介质蒸发可视化实验，揭示了蒸发过程中相界面移动、盐分结晶、以及角液膜流动之间的耦合作用机理，建立了角液膜中流动、蒸发、离子传输耦合的理论模型，获得影响传输过程三个主要无量纲数：毛细数，角液膜长度与孔隙尺度比、角液膜长度与蒸发边界层厚度比。本项目研究成果有力推动了多孔介质两相传输理论的发展。