Experimental Study On Multiple Bubbles Mass Transfer In A Turbulent Flow

In various gas-liquid reactors,the bubbles are mostly in the form of a bubbly swarm.The behavior of bubbles includes collision,coalescence,and bubble breakup in the bubbly swarm.In the gas-liquid mass transfer process,the mass transfer between single bubble and the surrounding liquid phase is used to replace the mass transfer behavior of multiple bubbles in the bubbly swarm,ignoring the influence of the interaction between the bubbles on the mass transfer,which is a practical problem.method for simplification.Therefore,this study aims to provide a theoretical basis for the mass transfer mechanism of multiple bubbles in complex turbulent systems by experimentally studying the gas-liquid mass transfer behavior of a limited number of multiple bubbles in the chamber flow.The chamber flow used in the study uses a 0.1 mol/L Na₂SO₃（at 30°C）,and a high-speed camera is used to record the image of the bubble movement process in the square cavity,and the image is analyzed to calculate the distance between the bubble and the surrounding liquid phase.gas-liquid mass transfer coefficient k _L.When the number of bubbles in the chamber flow is 1,2,3,4,5 and 6,it is found that the mass transfer coefficients of multiple bubble systems are all larger than those of a single bubble.Among them,in the case of single bubble,the mass transfer coefficient increases from 3.3×10^-4m/s to 5.7×10^-4m/s when the bubble diameter increases from 1.5 mm to 4.5 mm.In the case of multiple bubbles,as the number of bubbles increases,the average mass transfer coefficient of multiple bubbles increases first and then decreases,which may be related to the trajectory of the bubbles and the distance between the bubbles,that is,the contact between the bubbles will enhance the mass transfer coefficient.