Study On The Interfacial Turbulence In The Gas-Liquid Mass Transfer Process

In the mass transfer process, surface tension gradient and density gradient maycreate interfacial turbulence, which can increase the renewal of the interfacial liquid,by which the mass transfer coefficient increased largely. The interfacial turbulence isan effective way to enhance the mass transfer, and the research on interfacialturbulence is important to its application on manufacture.With the dual-path Schlieren system, the convective structures of interfacialturbulence during the mass transfer process were visualized for CO2absorption byand desorption from single organic solvent systems and volatilization of binarysystems. The results show that the schlieren images of the convective structuredevelop simultaneously at the horizontal direction and the vertical direction, and theschlieren image of one direction will be influence by another one. Both the schlierenimages of the two directions are influenced by the liquid layer thickness andcomposition. The schlieren image of the vertical direction directly indicated that theassumption of the quiet film theory is not accurate, and the interfacial turbulence willbe considered in the mass transfer process. The interfacial turbulence can increase therenewal of the interfacial liquid in the mass transfer process, which can enhance themass transfer rate.Through the criterion of the schlieren system and the measurement of therefractive index of ethanol aqueous and acetone aqueous, the schlieren images hadbeen analyzed quantitatively. The results show that the concentration gradient is thereason for the occurrence of the interfacial turbulence at the beginning of the masstransfer process. The surface tension gradients resulted from the concentrationgradient lead the interfacial turbulence to develop at the horizontal direction, and thegravity gradients resulted from the concentration gradient lead the interfacialturbulence to develop in the vertical direction. The simulation of the interfacialturbulence shows that local concentration reduction can destroy the equilibrium stateof the interface. The mass transfer rate is different for the inhomogenous surface, andthe concentration of the gas near the interface is different. The area vicinity to thesurface is not quiet for the interfacial turbulence destroys the equilibrium state of theinterface.