Experimental Investigation And Theoretical Simulation On Taylor Bubble In Minichannel With Non-Newtonian Fluids

With the continuous innovation and development of microchemical technology,the research on gas-liquid two-phase flow in microchannel has attracted much attention from scholars,the related research on gas-liquid two-phase flow and Taylor bubble characteristic behavior in millimeter-scale Minichannel widely used in energy chemical,composite materials and medical science fields is limited.In this paper,the combination of experimental observation and theoretical simulation was used to study the gas-liquid two-phase flow and Taylor bubble characteristic behavior in Minichannel with non-Newtonian fluids,which provides reference for the design and optimization of gas-liquid contact devices and the regulation mechanism of Taylor bubble behavior.In this paper,the high-speed camera is used to observe the gas-liquid two-phase flow behavior in the Minichannel,the effects of fluid type,sodium carboxymethylc cellulose?CMC?aqueous solution concentration and surfactant?sodium dodecyl sulfate?SDS?concentration on flow pattern were explored,meanwhile the effects of gas and liquid flow rate,CMC solution concentration and SDS concentration on Taylor bubble length,liquid column length,rise speed and generation frequency were investigated.The experimental results showed that five types of flow patterns were found in various solutions:bubbly flow,Taylor flow,Taylor-annular flow,annular flow and churn flow.In contrast to Newtonian fluid?H₂O?,in the viscoelastic non-Newtonian fluid?1.0%PAM?solution,the bubble flow and churn flow region are significantly enlarged,the Taylor-annular flow and annular flow region are slightly reduced,and the Taylor flow region change inconspicuously;In the purely viscous non-Newtonian fluid?1.0%CMC?solution,the Taylor flow region shrinks significantly,the bubbly flow and churn flow region are expanded;With the increase of CMC solution concentration and SDS concentration,the Taylor flow region shrinks,the bubbly flow and churn flow region are enlarged constantly.The Taylor bubble length increases with the increase of gas flow rate,but decreases with the increase of liquid flow rate,CMC solution concentration and SDS concentration;The liquid column length increases with the increase of liquid flow rate,but decreases with the increase of gas flow rate,CMC solution concentration and SDS concentration;Both the bubble rise velocity and the generation frequency increase with the increase of gas flow rate,liquid flow rate,CMC solution concentration and SDS concentration.Considering the rheological properties of non-Newtonian fluids,the gas-liquid two-phase flow and Taylor bubble behavior in the Minichannel with non-Newtonian fluids were numerically simulated by the method?CLSVOF?of coupling the horizontal set method?LS?and the fluid volume method?VOF?.The reliability and accuracy of the method were verified by validity verification and comparison with experimental results.The effects of fluid type,CMC solution concentration and SDS concentration on the flow pattern were studied,simultaneously the effects of gas and liquid flow rate,CMC solution concentration and SDS concentration on the thickness and curvature of Taylor bubble liquid film were also investigated by this method.The simulation results show that the above five flow patterns exist under different calculation conditions.Compared with H₂O,in the 1.0%PAM solution,the Taylor flow and churn flow region are slightly enlarged,the Taylor-annular flow and annular flow region are reduced obviously and the bubbly flow region does not change significantly;In the 1.0%CMC solution,the Taylor flow,bubbly flow and churn flow region are expanded,the Taylor-annular flow and annular flow region shrinks significantly;As the concentration of CMC solution concentration and SDS increases,the Taylor flow region shrinks by degrees,the bubbly flow and churn flow region continue to expand.The thickness of the liquid film becomes smaller as the gas flow rate increases,but becomes larger as the liquid flow rate,the CMC solution concentration and the SDS concentration increase;The curvature increases with the gas flow rate,liquid flow rate,CMC solution concentration and SDS concentration increase,the bubbly flow pattern also changes from Taylor flow to bubbly flow.