Study On The Influence Of Marangoni Effect And Other Factors On The Mass Transfer Coefficients

In the gas-liquid or liquid-liquid mass transfer process, interfacial tension gradient and density gradient can create interfacial turbulence, by which the mass transfer coefficient can be intensified. This interfacial turbulence is called Marangoni effect. During the process of the gas-liquid mass transfer, the Marangoni effect is the main source of creating interfacial turbulence. The purpose of present study was intended to proof the influence of the interfacial Marangoni effect by conducting an experiment of desorbing 2-propanol, diethyl ether, acetone and ethanol solution by nitrogen in the falling film process. If the Marangoni effect creates interfacial turbulence, the mass transfer coefficient can be intensified, the ignorance of such effect will result inaccurate evaluation of a mass transfer process. It was found that the interfacial Marangoni effect has a significant intensification on the mass transfer coefficient, the extent of which can be represented by introducing an enhancement factor F. Among the published correlations for predicting the gas-liquid mass transfer coefficient in the falling film process, the Marangoni effect was always being ignored. By fitting our experimental data and reference data, a new correlation of mass transfer coefficient was proposed, in which the dimensionless Sherwood number, ShL, was expressed as a function of the dimensionless Marangoni number, Ma. The evaluation of the parameters of the new correlation was demonstrated. The proposed correlation is in good agreement with the experimental data and reference data. In this dissertation, a mass transfer coefficient database is set up, from which the conclusive study on the influence of flow rate of the liquid, the flow rate of the gas, physical properties, temperature, pressure and Marangoni effect on the mass transfer coefficient is presented.