润湿特性对多孔介质缓慢干燥过程影响的数值模拟

Numerical Simulation of Influence of Wetting Property on Slow Drying of Porous Media

采用二维孔隙网络模型,对不同孔隙结构下亲水多孔介质与憎水多孔介质的缓慢干燥过程进行模拟,考察润湿特性的改变对二维多孔介质干燥过程中液相分布、蒸发速率以及干燥总时间的影响。模拟结果表明,忽略重力与黏性力影响时,多孔介质干燥过程只受毛细压力控制,亲水多孔介质蒸发端为无规则形状,而憎水多孔介质蒸发端则根据孔隙尺寸分布与喉孔比的不同呈现不同的特性;干燥总时间与润湿特性、蒸发速率、孔隙结构相关;当喉孔比相同时,紧凑多孔介质的干燥总时间小于非紧凑多孔介质;当喉孔比较小时,亲水多孔介质的干燥总时间小于憎水多孔介质;当喉孔比较大时,憎水与亲水多孔介质的干燥总时间可以近乎相等。

The slow drying processes of hydrophilic and hydrophobic porous media with different pore structure were simulated by using a pore network model and the influences of wetting property on evaporation behavior were investigated.The simulation results indicated that when adhesion and gravity were ignored,capillary pressure dominated the drying processes; the drying front ends in the hydrophilic porous media kept irregular shape,but in the hydrophobic porous media the drying front ends showed different features according to the pore size distribution（PSD） and throat-pore ratio; the total drying time was affected by the evaporation rate,pore structure and wetting property.For the wide PSD network,the total drying time of the hydrophilic porous media is less than that of the hydrophobic porous media when the throat-pore ratio is low.For the narrow PSD,the total drying time of the hydrophobic porous media is similar to that of the hydrophilic porous media when the throat-pore ratio is high.