Comparative study on the flow and mass transfer characteristics of sub-millimeter bubbles and conventional bubbles in gas-liquid two-phase flow
The differences in flow and mass transfer characteristics between a sub-millimeter bubble column and a conventional bubble column were explored systematically by using experimental and numerical simulation methods.A specific numerical simulation approach was proposed for the flow and mass transfer processes of sub-millimeter bubbles in gas-liquid bubbly flow.The results reveal that,under comparable operating conditions,the size distribution of bubbles in sub-millimeter bubble columns is narrower,with an average size reduced to approximately 3%of that observed in conventional columns.Moreover,the gas holdup increases by over two-fold,and the interfacial area enhances by two orders of magnitude.In addition,the radial distribution of gas and liquid in the submillimeter bubble gas-liquid two-phase flow is more uniform,and the degree of axial backmixing is smaller.Notably,the interfacial area within sub-millimeter bubble columns plays a pivotal role in intensifying mass transfer,even though their liquid-side mass transfer coefficient is lower compared to conventional columns.Leveraging the substantial interfacial area,the volumetric mass transfer coefficient within sub-millimeter bubble columns is approximately ten times that within conventional columns.Notably,simulation outcomes for large-scale bubble column reactors indicate that sub-millimeter bubbles have the potential to yield a more uniform gas holdup distribution,thereby exhibiting reduced sensitivity to initial gas-liquid distribution effects.
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维普
