Effect of Marangoni Convection on Mass Transfer in Liquid Phase

Marangoni convection and its influence on the mass transter in the liquid phase were investigated. Marangoni convection was visualized using laser Schlieren technique, Orderly polygonal convection patterns and random interfacial turbulence were observed. The effect of Marangoni convection on the mass transfer rate was studied by desorbing ethanol from aqneous solution in the falling film. The experimental results show that Marangoni convection can speed up the surface real and enhance the mass transfer rate in the liquid phase.The liquid mass transfer coefficient can be enhanced by as much as 3 folds. The corresponding empirical correlations are given in terms of the mass transfer enhancement factor. Furthermore, in considering the Marangoni effect, the conventional mass transfer correlation was modified, The differences between the values predicted by the correlation and the experimental data are within ±8.2% and the average difference is 4.2%.

膜内气压和液相流速对无泡膜曝气氧传质性能的影响

探究了膜内气压（P）及液相流速对无泡膜曝气氧传质性能的影响。结果表明，当P在2kPa以下时，随着P增加，氧传质系数增加；当P为2～10kPa时，随着P增加，氧传质系数逐渐降低。当液相流速从0．014m／s增加到0．041m／s时，氧传质系数呈上升趋势，但增加幅度不大。同时给出了膜曝气反应器内舍伍德数（Sh）随膜内气压、雷诺数（Re）和施密特数（So）的变化关系式，当P为0～2kPa时，跏与P呈正相关，说明氧传质性能随压强的升高而增强；当P为2～10kPa时，肌与P呈负相关，说明此时氧传质性能随压强的升高而减弱。