Interphase mass transfer in gas-liquid bubble columns is commonly modeled using three distinct theoretical frameworks:single-bubble theory,gas-liquid slip velocity assumption,and eddy-bubble interactions.This study pr...Interphase mass transfer in gas-liquid bubble columns is commonly modeled using three distinct theoretical frameworks:single-bubble theory,gas-liquid slip velocity assumption,and eddy-bubble interactions.This study presents,for the firsttime,a comparative computational fluiddynamic-population balance model(CFD-PBM)evaluation under both co-current and counter-current flows,systematically assessing fiveestablished models-Ranz-Marshall and Brauer(single-bubble model),Higbie and Bird(slip velocity model),and Kawase(eddy cell model)-within the ANSYS Fluent two-fluidframework.The simulations are rigorously validated against experimental CO_(2) absorption/desorption data encompassing both co-current and counter-current flowconfigurations.Results indicate that the Kawase eddy cell model shows agreement within±15%with experimental measurements,particularly under counter-current conditions,due to its incorporation of turbulence effects.While the single-bubble model(Brauer)and the slip velocity approach(Higbie and Bird)reproduce qualitative trends,they exhibit considerable quantitative deviations.The Ranz-Marshall model proves inadequate for accurate mass transfer predictions.Analysis of bubble size distribution reveals its strong dependence on flowregimes.Notably,counter-current operation significantlyenhances mass transfer performance compared to co-current flow,primarily through increased gas holdup and enhanced turbulent mixing.These insights offer valuable guidance for both model selection and the design optimization of bubble column reactors.展开更多
Electrolytes hold the key to realizing reliable zinc(Zn)anodes.Divergent organic molecules have been proven effective in stabilizing Zn anodes;however,irrational comparisons exist due to the uncontrolled molecular wei...Electrolytes hold the key to realizing reliable zinc(Zn)anodes.Divergent organic molecules have been proven effective in stabilizing Zn anodes;however,irrational comparisons exist due to the uncontrolled molecular weights and functional group amounts.In this work,two“isomeric molecules”:1,2-dimethoxyethane(DME)and 1-methoxy-2-propanol(PM),with identical molecular weights but different functional groups,have been studied as co-solvents in electrolytes,which have delivered distinct electrochemical performance.Experimental and simulative study indicates the dipole moment induced by the hydroxyl groups in PM(higher molecular polarity than ether groups in DME)reconstructs the space charge region,enhances the concentration of Zn^(2+)in the vicinity of Zn anodes,and in-situ derives different solid electrolyte interphase(SEI)models and electrode-electrolyte interfaces,resulting in exceptional cycling stability.Remarkably,the Zn||Cu cell with PM worked over 2000 cycles with high Coulombic efficiency(CE)of 99.7%.The Zn||Zn symmetric cell cycled over 2000 h at 1 mA·cm^(−2),and showed excellent stability at an ultrahigh current density of 10 mA·cm^(−2)and capacity of 20 mAh·cm^(−2)over 200 h(depth of discharge,DOD of 70%).The Zn||sodium vanadate pouch cell with a high mass loading of 6.3 mg·cm^(−2)and a high capacity of 24 mAh demonstrates superior cyclability after 570 h.This work can be a good starting point to provide reliable guidance on electrolyte design for practical aqueous Zn batteries.展开更多
文摘Interphase mass transfer in gas-liquid bubble columns is commonly modeled using three distinct theoretical frameworks:single-bubble theory,gas-liquid slip velocity assumption,and eddy-bubble interactions.This study presents,for the firsttime,a comparative computational fluiddynamic-population balance model(CFD-PBM)evaluation under both co-current and counter-current flows,systematically assessing fiveestablished models-Ranz-Marshall and Brauer(single-bubble model),Higbie and Bird(slip velocity model),and Kawase(eddy cell model)-within the ANSYS Fluent two-fluidframework.The simulations are rigorously validated against experimental CO_(2) absorption/desorption data encompassing both co-current and counter-current flowconfigurations.Results indicate that the Kawase eddy cell model shows agreement within±15%with experimental measurements,particularly under counter-current conditions,due to its incorporation of turbulence effects.While the single-bubble model(Brauer)and the slip velocity approach(Higbie and Bird)reproduce qualitative trends,they exhibit considerable quantitative deviations.The Ranz-Marshall model proves inadequate for accurate mass transfer predictions.Analysis of bubble size distribution reveals its strong dependence on flowregimes.Notably,counter-current operation significantlyenhances mass transfer performance compared to co-current flow,primarily through increased gas holdup and enhanced turbulent mixing.These insights offer valuable guidance for both model selection and the design optimization of bubble column reactors.
基金We acknowledge the financial support from the Open Research Fund of Songshan Lake Materials Laboratory(No.2021SLABFN04)the National Natural Science Foundation of China(Nos.22005207 and U20A20249)the Regional Innovation and Development Joint Fund,and the Science and Technology Program of Guangdong Province of China(No.2022A0505030028).
文摘Electrolytes hold the key to realizing reliable zinc(Zn)anodes.Divergent organic molecules have been proven effective in stabilizing Zn anodes;however,irrational comparisons exist due to the uncontrolled molecular weights and functional group amounts.In this work,two“isomeric molecules”:1,2-dimethoxyethane(DME)and 1-methoxy-2-propanol(PM),with identical molecular weights but different functional groups,have been studied as co-solvents in electrolytes,which have delivered distinct electrochemical performance.Experimental and simulative study indicates the dipole moment induced by the hydroxyl groups in PM(higher molecular polarity than ether groups in DME)reconstructs the space charge region,enhances the concentration of Zn^(2+)in the vicinity of Zn anodes,and in-situ derives different solid electrolyte interphase(SEI)models and electrode-electrolyte interfaces,resulting in exceptional cycling stability.Remarkably,the Zn||Cu cell with PM worked over 2000 cycles with high Coulombic efficiency(CE)of 99.7%.The Zn||Zn symmetric cell cycled over 2000 h at 1 mA·cm^(−2),and showed excellent stability at an ultrahigh current density of 10 mA·cm^(−2)and capacity of 20 mAh·cm^(−2)over 200 h(depth of discharge,DOD of 70%).The Zn||sodium vanadate pouch cell with a high mass loading of 6.3 mg·cm^(−2)and a high capacity of 24 mAh demonstrates superior cyclability after 570 h.This work can be a good starting point to provide reliable guidance on electrolyte design for practical aqueous Zn batteries.
