旋流场中小颗粒污染物凝并及运动特性研究?
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摘要
为研究旋流对小颗粒凝并过程的影响,研究通过整合Lech Gmachowski Brown凝并核模型、湍流凝并核模型和XIAO提出的剪切破碎核模型,建立了一个考虑剪切流影响的适用于全粒径范围的颗粒凝并模型。首先计算了初始粒径为0.5μm的颗粒凝并效率,对比前人实验数据,验证了新模型对于湍流场过渡区内颗粒凝并行为的适应性。然后考察了旋流运动对亚微米和微米级颗粒凝并的影响,结果表明,旋流影响了亚微米级颗粒的自由扩散,促使不同粒径颗粒分离,从而降低凝并效率;对于微米级颗粒,旋流增加了小颗粒的碰撞概率,但无法提升凝并效果,旋流速度越高,凝并效果越差;在旋流场中设置轴向扰流板,可以改善小颗粒凝并效果。
In order to investigate effects of swirl flow on coagulation, a model for particle coagulating simulation was established by combining Lech Gmachowski Brown model, turbulence coagulation model and shearing-induced breakup model proposed by XIAO. Shear effects were considered and the new model can be used for all particle sizes. Simulation and experimental results were compared in terms of coagulating efficiency for 0.5 μm particles, and the results confirmed that the model can accurately predict coagulation in the transition region in a turbulence field. Coagulation behavior of micron and submicron particles in swirl flow was then studied, and the results showed that swirling affected free diffusion of submicron particles,which caused different size particle separation and leads to reduction in coagulation efficiency. Swirling flow increases collision for small particles but coagulation efficiency cannot be improved. Coagulation efficiency decreases when swirl increases. Axial plate added in the swirling field can significantly improve coagulation efficiency.
In order to investigate effects of swirl flow on coagulation, a model for particle coagulating simulation was established by combining Lech Gmachowski Brown model, turbulence coagulation model and shearing-induced breakup model proposed by XIAO. Shear effects were considered and the new model can be used for all particle sizes. Simulation and experimental results were compared in terms of coagulating efficiency for 0.5 μm particles, and the results confirmed that the model can accurately predict coagulation in the transition region in a turbulence field. Coagulation behavior of micron and submicron particles in swirl flow was then studied, and the results showed that swirling affected free diffusion of submicron particles,which caused different size particle separation and leads to reduction in coagulation efficiency. Swirling flow increases collision for small particles but coagulation efficiency cannot be improved. Coagulation efficiency decreases when swirl increases. Axial plate added in the swirling field can significantly improve coagulation efficiency.
引文
[1]张会君,卢徐胜.控制PM2.5的除尘技术概述[J].中国环保产业,2012,3:29-33.ZHANG H J,LU X S.Explication on controlling PM2.5 precipitation technology[J].China Environmental Protection Industry,2012,3:29-33.
[2]陈亚伟,熊扬恒,周建龙,等.凝并元件结构优化对气固两相流流场及颗粒凝并效果的影响[J].热力发电,2016,45(1):60-64.CHEN Y W,XIONG Y H,ZHOU J L,et al.Influence of coagulation element structure optimization on gas-solid two-phase flow field and particulate coagulation[J].Thermal Power Generation,2016,45(1):60-64.
[3]刘含笑,姚宇平,郦建国,等.凝聚器二维单扰流柱流场中颗粒凝并模拟[J].动力工程学报,2015,35(4):292-297.LIU H X,YAO Y P,LI J G,et al.Coagulating simulation of particles in flow field of coagulator 2D single turbulence column[J].Journal of Chinese Society of Power Engineering,2015,35(4):292-297.
[4]刘定平,罗伟乐.基于旋流与声波的颗粒复合凝并建模与运动轨迹仿真[J].动力工程学报,2017,37(5):413-417.LIU D P,LUO W L.Moving trajectory simulation of particles and modeling of the complex coagulation based on swirl and acoustic wave[J].Journal of Chinese Society of Power Engineering,2017,37(5):413-417.
[5]TEICHMANN J,BOOGAART K G VAN DEN.Cluster models for random particle aggregates-Morphological statistics and collision distance[J].Spatial Statistics,2015,12:65-80.
[6]PESMAZOGLOU I,KEMPF S,NAVARRO-MARTINEZ.Large eddy simulation of particle aggregation in turbulent jets[J].Journal of Aerosol Science,2017,111:1-17.
[7]LEE S H.Numerical study of aggregation and breakage of particles in taylor reactor[J].Transactions of the Korean Society of Mechanical Engineers B,2016,40(6):365-372.
[8]HARSHE Y M,LATTUADa M.Breakage rate of colloidal aggregates in shear flow through stokesian dynamics[J].Langmuir,2012,28(1):283-292.
[9]FENG X,HUI X,XIAO Y L,et al.Modelling particle-size distribution dynamics in a shear-induced breakage process with an improved breakage kernel:Importance of the internal bonds[J].Colloid s and Surfaces,2015,468:87-94.
[10]徐挺,魏文韫,孙白宇,等.气液交叉流脱除亚微米级颗粒物的研究[J].高校化学工程学报,2017,31(4):960-969.XU T,WEI W Y,SUN B Y,et al.Study on sub-micron particle removal by gas-liquid cross-flow array systems[J].Journal of Chemical Engineering of Chinese Universities,2017,31(4):960-969.
[11]SMOLUCHOWSKI M V.Experiments on a mathematical theory of kinetic coagulation of colloid solution[J].Zeitschrift Fur Physikalische Chemie-Stochiometrie Und Verwandtschaftslehre,1992,2:1777-1786.
[12]BANHELMES G,PRATSINIS S E,BUGGISCH H.Particle size distributions and viscosity of suspensions undergoing Shear-induced coagulation and fragmentation[J].Chemical Engineering Science,2003,58(13):2893-2902.
[13]YIMER I,CAMPBELL I,JIANG L.Estimation of the turbulent Schmidt number from experimental profiles of axial velocity and concentration for high-reynolds-number jet flows[J].Canandian Aeronautics and Space Journal,2002,48(3):95-200.
[14]LAW A W K.Velocity and concentration distributions of round and plane turbulent jets[J].Journal of Engineering Mathematics,2006,56(1):69-78.
[15]HO C A,SOMMERFELD M.Modelling of micro-particle agglomeration in turbulent flows[J].Chemical Engineering Science,2002,57(15):3073-3084.
[16]FLAGAN R C,SAROFIM A F.Coal generated inorganic aerosol:A review[C].First international Aerosol Conference,1984,23(4):778-782.
[17]GMACHOWSKI L.The aerosol particle collision kernel considering the fractal model of particle motion[J].Journal of Aerosol Science,2013,59:47-56.
[18]FUCHS N A,SUTUGIN A G.Hihgly dispersed aerosols[M].London:Ann Arbor Science Publishers,1970.
[19]XIAO F,LI X Y.Modelling the kinetics of aggregate breakage using improved breakage kernel[J].Water Science and Technology,2008,57(1):151-157.
[20]ODRIOZOLA G,SCHMITT A,MONCHO-JORDA A,et al.Constant bond breakup probability model for reversible aggregation processes[J].Physical Review E,2002,65(3):151-156.
[21]徐俊波,张丽,岳仁亮,等.PM2.5细颗粒物凝并的计算流体力学模拟[J].计算机与应用化学,2013,30(80):831-834.XU J B,ZHANG L,YUE R L,et al.Computational fluid dynamics simulation of coagulation of PM2.5 fine particles[J].Computers and Applied Chemistry,2013,30(80):831-834.
[22]PATRUNO L E.Analysis of breakage kernels for population balance modelling[J].Chemical Engineering Science,2009,64:501-508.
[2]陈亚伟,熊扬恒,周建龙,等.凝并元件结构优化对气固两相流流场及颗粒凝并效果的影响[J].热力发电,2016,45(1):60-64.CHEN Y W,XIONG Y H,ZHOU J L,et al.Influence of coagulation element structure optimization on gas-solid two-phase flow field and particulate coagulation[J].Thermal Power Generation,2016,45(1):60-64.
[3]刘含笑,姚宇平,郦建国,等.凝聚器二维单扰流柱流场中颗粒凝并模拟[J].动力工程学报,2015,35(4):292-297.LIU H X,YAO Y P,LI J G,et al.Coagulating simulation of particles in flow field of coagulator 2D single turbulence column[J].Journal of Chinese Society of Power Engineering,2015,35(4):292-297.
[4]刘定平,罗伟乐.基于旋流与声波的颗粒复合凝并建模与运动轨迹仿真[J].动力工程学报,2017,37(5):413-417.LIU D P,LUO W L.Moving trajectory simulation of particles and modeling of the complex coagulation based on swirl and acoustic wave[J].Journal of Chinese Society of Power Engineering,2017,37(5):413-417.
[5]TEICHMANN J,BOOGAART K G VAN DEN.Cluster models for random particle aggregates-Morphological statistics and collision distance[J].Spatial Statistics,2015,12:65-80.
[6]PESMAZOGLOU I,KEMPF S,NAVARRO-MARTINEZ.Large eddy simulation of particle aggregation in turbulent jets[J].Journal of Aerosol Science,2017,111:1-17.
[7]LEE S H.Numerical study of aggregation and breakage of particles in taylor reactor[J].Transactions of the Korean Society of Mechanical Engineers B,2016,40(6):365-372.
[8]HARSHE Y M,LATTUADa M.Breakage rate of colloidal aggregates in shear flow through stokesian dynamics[J].Langmuir,2012,28(1):283-292.
[9]FENG X,HUI X,XIAO Y L,et al.Modelling particle-size distribution dynamics in a shear-induced breakage process with an improved breakage kernel:Importance of the internal bonds[J].Colloid s and Surfaces,2015,468:87-94.
[10]徐挺,魏文韫,孙白宇,等.气液交叉流脱除亚微米级颗粒物的研究[J].高校化学工程学报,2017,31(4):960-969.XU T,WEI W Y,SUN B Y,et al.Study on sub-micron particle removal by gas-liquid cross-flow array systems[J].Journal of Chemical Engineering of Chinese Universities,2017,31(4):960-969.
[11]SMOLUCHOWSKI M V.Experiments on a mathematical theory of kinetic coagulation of colloid solution[J].Zeitschrift Fur Physikalische Chemie-Stochiometrie Und Verwandtschaftslehre,1992,2:1777-1786.
[12]BANHELMES G,PRATSINIS S E,BUGGISCH H.Particle size distributions and viscosity of suspensions undergoing Shear-induced coagulation and fragmentation[J].Chemical Engineering Science,2003,58(13):2893-2902.
[13]YIMER I,CAMPBELL I,JIANG L.Estimation of the turbulent Schmidt number from experimental profiles of axial velocity and concentration for high-reynolds-number jet flows[J].Canandian Aeronautics and Space Journal,2002,48(3):95-200.
[14]LAW A W K.Velocity and concentration distributions of round and plane turbulent jets[J].Journal of Engineering Mathematics,2006,56(1):69-78.
[15]HO C A,SOMMERFELD M.Modelling of micro-particle agglomeration in turbulent flows[J].Chemical Engineering Science,2002,57(15):3073-3084.
[16]FLAGAN R C,SAROFIM A F.Coal generated inorganic aerosol:A review[C].First international Aerosol Conference,1984,23(4):778-782.
[17]GMACHOWSKI L.The aerosol particle collision kernel considering the fractal model of particle motion[J].Journal of Aerosol Science,2013,59:47-56.
[18]FUCHS N A,SUTUGIN A G.Hihgly dispersed aerosols[M].London:Ann Arbor Science Publishers,1970.
[19]XIAO F,LI X Y.Modelling the kinetics of aggregate breakage using improved breakage kernel[J].Water Science and Technology,2008,57(1):151-157.
[20]ODRIOZOLA G,SCHMITT A,MONCHO-JORDA A,et al.Constant bond breakup probability model for reversible aggregation processes[J].Physical Review E,2002,65(3):151-156.
[21]徐俊波,张丽,岳仁亮,等.PM2.5细颗粒物凝并的计算流体力学模拟[J].计算机与应用化学,2013,30(80):831-834.XU J B,ZHANG L,YUE R L,et al.Computational fluid dynamics simulation of coagulation of PM2.5 fine particles[J].Computers and Applied Chemistry,2013,30(80):831-834.
[22]PATRUNO L E.Analysis of breakage kernels for population balance modelling[J].Chemical Engineering Science,2009,64:501-508.