| Marangoni convection, which is a kind of interfacial turbulence, is induced and maintained by the surface tension gradient on the interface. It affects the fluid flow significantly as well as the interfacial mass transfer process. Therefore, the investigation of Marangoni convection can help understanding mass transfer mechanism and designing new and efficient mass transfer equipment.In this paper, a gas-liquid mass transfer simulator was established. By particle image velocimetry (PIV), Marangoni convection induced by CO2 desorption from ethanol, acetone and ethyl acetate were observed respectively. The influences of the gas flow rate and Ma number were investigated respectively. Liquid velocity field on a cross section perpendicular to the interface was obtained and analyzed qualitatively and quantitatively. The experimental results showed the occurrences of the maximum velocity, turbulence kinetic energy and vorticity near the interface. It was found that with the increase of Ma number, the number and the diameter of the vortex gradually increased.Gas-liquid mass transfer resistance usually concentrates at the interface. Because of the large rotary and turbulent intensity of the interfacial fluid due to the large vorticity and turbulence kinetic energy at the interface, the mass transfer resistance decreases; and consequently, Marangoni convection is conducive to the gas-liquid mass transfer process. With the increase of the gas flow rate, the mass transfer driving force and so the surface tension gradient may be getting larger, and this explains the fact that the Marangoni convection is intensified in case of larger gas velocity.The results show that the flow velocity of Marangoni covection is significantly greater than that by diffusion. In addition, the Péclet number is calculated to demonstrate the ratio of advection to diffusion. With the help of Pe, we can determine when Marangoni convection occurs and how Marangoni convection influences mass transfer. |
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