除尘管道内铝粉运移及沉积的数值研究
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摘要
基于DPM(Discrete Phase Model)模型,研究了长直通风管道内粒径服从Rosin-Rammler分布的铝粉的运移与沉积规律.基于颗粒与壁面的碰撞过程中的能量分析,建立了粉尘沉积-回弹模型,得出了粉尘沉积的判定准则及脱离壁面时的回弹速度.利用UDF将沉积-回弹模型嵌入Fluent,完成了对管道内粉尘运移和沉积的数值模拟.粉尘沉积的数值结果与实验结果符合得较好,验证了所提模型的有效性.数值结果表明风速的增大使管道内粉尘浓度明显降低,管壁粉尘沉积率也降低;粒径的增大对粉尘浓度的大小影响不明显,主要影响粉尘浓度在管道内的分布情况,同时会增大粉尘在管壁的沉积率.
The transportation and deposition of aluminum particles, whose size obey the Rosin-Rammler distribution, in a long straight pipeline is investigated numerically using DPM(Discrete Phase Model). A Particle deposition-rebounding model is established based on the energy analysis during particle-to-wall collision, and the particle rebounding velocity from the wall and the criteria for deposition are obtained. Embedding the deposition-rebounding model into Fluent via UDF, the transportation and deposition of particles is simulated. Numerical results of deposition rate are in good agreement with the experimental results, which verifies the effectiveness of the deposition-rebounding model proposed. The study shows that the increase of wind speed decreases the dust concentration in the pipeline dramatically and also decreases the dust deposition rate at the bottom of the pipeline. The increase of the particle size has little effect on the dust concentration, which mainly affects the distribution of dust concentration in the pipeline and increases the deposition rate at the bottom of the pipeline.
The transportation and deposition of aluminum particles, whose size obey the Rosin-Rammler distribution, in a long straight pipeline is investigated numerically using DPM(Discrete Phase Model). A Particle deposition-rebounding model is established based on the energy analysis during particle-to-wall collision, and the particle rebounding velocity from the wall and the criteria for deposition are obtained. Embedding the deposition-rebounding model into Fluent via UDF, the transportation and deposition of particles is simulated. Numerical results of deposition rate are in good agreement with the experimental results, which verifies the effectiveness of the deposition-rebounding model proposed. The study shows that the increase of wind speed decreases the dust concentration in the pipeline dramatically and also decreases the dust deposition rate at the bottom of the pipeline. The increase of the particle size has little effect on the dust concentration, which mainly affects the distribution of dust concentration in the pipeline and increases the deposition rate at the bottom of the pipeline.
引文
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[19]HOSSEINI S B,KHOSHKHOO R H,MALABAD S M J.Numerical study on polydisperse particle deposition in a compact heat exchanger[J].Applied Thermal Engineering,2017,127:330-346.
[2]BRACH R,DUNN P.A Mathematical model of the impact and adhesion of microsphers[J].Aerosol Science&Technology,1992,16(1):51-64.
[3]BRACH R M,DUNN P F,LI X.Experiments and engineering models of microparticle impact and deposition[J].Journal of Adhesion,2000,74(1-4):227-282.
[4]LI X,DUNN P F,BRACH R M.Lycopodium spore impacts onto surfaces[J].Atmospheric Environment,2000,34(10):1575-1581.
[5]MEHDI S,GOODARZ A.On particle adhesion and removal mechanisms in turbulent flows[J].Journal of Adhesion Science&Technology,1994,8(7):763-785.
[6]EL-BATSH H,HASELBACHER H.Numerical investigation of the effect of ash particle deposition on the flow field through turbine cascades[C]//ASME Turbo Expo 2002:Power for Land,Sea,and Air.2002,1035-1043.
[7]AI W,KUHLMAN J M.Simulation of coal ash particle deposition experiments[J].Molecular&Cellular Biology,2011,5(10):2874-2877.
[8]潘亚娣,司风琪,徐治皋.电站锅炉受热面灰污沉积模型[J].中国电机工程学报,2010,30(8):63-67.
[9]潘亚娣,司风琪,徐治皋.电站锅炉受热面灰污剥离模型[J].中国电机工程学报,2010,30(11):33-37.
[10]KERN D Q,SEATON R E.A theoretical analysis of thermal surface fouling[J].British Chemical Engineering,1959,4(5):258-262.
[11]KERN D Q,SEATON R E.Surface fouling:how to calculate limits[J].Chemical Engineering Progress,1959,55(6):71-73.
[12]WALSH P M,SAYRE A N,LOEHDEN D O,et al.Deposition of bituminous coal ash on an isolated heat exchanger tube:effects of coal properties on deposit growth[J].Progress in Energy&Combustion Science,1990,16(4):327-345.
[13]LEE F C C,LOCKWOOD F C.Modelling ash deposition in pulverized coal-fired applications[J].Progress in Energy&Combustion Science,1998,25(2):117-132.
[14]FANG Q,WANG H,WEI Y,et al.Numerical simulations of the slagging characteristics in a down-fired,pulverized-coal boiler furnace[J].Fuel Processing Technology,2010,91(1):88-96.
[15]王苑,张品,林鹏云,等.链条炉飞灰沉积的数值模型与计算[J].热能动力工程,2011,26(2):207-211.
[16]李冲.飞灰复燃颗粒沉积数值模拟[D].大连:大连理工大学,2014.
[17]李素芬,安岩.飞灰复燃对炉内颗粒沉积状况的影响分析[J].热科学与技术,2012,11(2):163-169.
[18]TOMECZEK J,WAC?AWIAK K.Two-dimensional modelling of deposits formation on platen superheaters in pulverized coal boilers[J].Fuel,2009,88(8):1466-1471.
[19]HOSSEINI S B,KHOSHKHOO R H,MALABAD S M J.Numerical study on polydisperse particle deposition in a compact heat exchanger[J].Applied Thermal Engineering,2017,127:330-346.