多尺度多孔介质的有效气体渗透率研究

The Effective Gas Permeability of Porous Media With Multi-scale Pore Structure

多孔介质的气体渗透率对于油气资源、微机电系统、燃料电池、生物组织、纤维以及复合材料等具有重要的理论和实际意义。然而,多孔介质内孔隙结构和连通性十分复杂,孔隙尺度范围极广,从常规尺度到微纳米尺度形成了多尺度并存的物理结构,气体在多尺度孔隙结构中的流动涉及多种输运机制。本文基于分形几何理论,建立了多尺度多孔介质气体渗流的物理和数学模型,理论推导了多尺度多孔介质的有效气体渗透率,研究了多孔介质的微结构参数对于有效气体渗透率的定量影响。结果表明,多尺度多孔介质的气体输运过程不仅依赖于介质的微细结构还依赖于气体属性,微纳尺度孔隙的气体滑移效应显著。

Gas permeability of porous media is of great theoretical and practical importance for oil and gas resources, micro-electro-mechanical systems, fuel cells, biological tissues, fibrous and composite materials etc. However, the pore structure and its connectivity in porous media are very complex, and the multi-scale pores with size from normal to micro/nano scale coexist. Therefore,gas flow thorough multi-scale porous media involves several different transport mechanisms. In this work, a physical and mathematical model is developed to study the gas flow thorough multi-scale porous media based on fractal geometry. The effective gas permeability is derived, and the effect of structural parameters of porous media on the effective gas permeability is analyzed accordingly. The present results indicate that gas flow in multi-scale porous media depends on both the microstructure and gas property, and the gas slippage effect in micro-and nano-scale pores is significant.