Moisture Transport in Unconsolidated Porous Media During Drying

该项目涉及对颗粒状多孔介质干燥过程中水分传输过程的实验研究。从原理上讲，机理很简单--由于分压的梯度，水蒸气在气相中的扩散，以及由于毛细管力在液体中的对流。最近的可视化研究清楚地表明，局部非均质性的影响由两个参数主导：键数(表面张力效应与重力效应的比率)和颗粒尺寸分布的方差。为了探索大范围的邦德数字，研究人员将使用范围从100微米到1000微米的玻璃球体填充床。将使用球形颗粒的混合物和碎玻璃颗粒的混合物来探索颗粒尺寸分布的变化的影响。

This project involves an experimental study of the moisture transport process that occurs during the drying of granular porous media. In principle, the mechanisms are quite simple--diffusion of water vapor in the gas phase owing to gradients in the partial pressure and convection in the liquid phase owing to capillary forces. Recent visual studies have clearly indicated that the influence of local heterogeneities is dominated by two parameters: the Bond number (ratio of surface tension effects to gravitiational effects) and the variance of the particle size distribution. To explore a wide range of Bond numbers, the investigator will use packed beds of glass spheres ranging from 100 to 1000 microns. The influence of the variance of the particle size distribution will be explored using mixtures of spherical particles and mixtures of crushed glass particles.