机械振动对纳米颗粒聚团流化的影响
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摘要
在常温常压下,通过测定SiO_2,Al_2O_3和TiO_2三种不同纳米颗粒的床层压降和床层膨胀曲线的方法,研究机械振动对纳米颗粒流态化的影响。结果表明:在振动条件下纳米颗粒临界流化速度和床层膨胀比略低,且床层压降和床层膨胀曲线较平稳,纳米颗粒流化滞后现象减弱。在恒定振频条件下,振幅越大纳米颗粒流化效果越好。在恒定振幅条件下,振频对纳米颗粒流化行为的影响呈现两种趋势,较低振频下随振频的增加流化效果变好。当超过某一定值时,继续增大振频流化效果反而变差。
At normal temperature and pressure, the influence of mechanical vibration on the fluidization of nanoparticles was studied by measuring the bed pressure drop and bed expansion curve of three different nanoparticles,SiO_2, Al_2 O_3 and Ti O_2. Results show that minimum fluidization velocity and the bed expansion ratio of the nanoparticles are slightly lower under the vibration conditions, and the bed pressure drop and the bed expansion curve are relatively stable, and the nanoparticle fluidization hysteresis attenuated. In constant vibration frequency conditions, the fluidization of the nanoparticles become batter with the increase of vibration amplitude; in the constant vibration amplitude, the effect of the vibration frequency on the fluidization behavior of nanoparticle presents two trends. At lower vibration frequencies, the fluidization effect becomes better with the increase of vibration frequency. When a certain value is exceeded, the fluidization effect becomes worse with the increase of vibration frequency.
At normal temperature and pressure, the influence of mechanical vibration on the fluidization of nanoparticles was studied by measuring the bed pressure drop and bed expansion curve of three different nanoparticles,SiO_2, Al_2 O_3 and Ti O_2. Results show that minimum fluidization velocity and the bed expansion ratio of the nanoparticles are slightly lower under the vibration conditions, and the bed pressure drop and the bed expansion curve are relatively stable, and the nanoparticle fluidization hysteresis attenuated. In constant vibration frequency conditions, the fluidization of the nanoparticles become batter with the increase of vibration amplitude; in the constant vibration amplitude, the effect of the vibration frequency on the fluidization behavior of nanoparticle presents two trends. At lower vibration frequencies, the fluidization effect becomes better with the increase of vibration frequency. When a certain value is exceeded, the fluidization effect becomes worse with the increase of vibration frequency.
引文
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[2] Pratsinis S E. Aerosol-based technologies in nanoscale manufacturing:from functional materials to devices through core chemical engineering[J]. AICh E Journal, 2010, 56:3028-3035.
[3] Zhu C, Liu G, Yu Q, et al. Sound assisted fluidization of nanoparicle agglomerates[J]. Powder Technology, 2004,141(1-2):119-23.
[4] Zeng P, Zhou T, Yang J. Behavior of mixtures of nano-particles in magnetically assisted fluidized bed[J]. Chemical Engineering and Processing:Process Intensification, 2008, 47(1):101-8.
[5] Quintanilla M A S, Valverde J M, Espin M J, et al. Electrofluidization of silica nanoparticle agglomerates[J]. Industrial&Engineering Chemistry Research, 2012, 51(1):531-538.
[6] Yang J S, Zhou T, Song L Y. Agglomerating vibro-fluidization behavior of nanoparticles[J]. Advanced Powder Technology,2009,20(2):158-163.
[7]唐洪波,赵珺.微细粉体在振动流化床的聚团行为研究[J].化学工业与工程, 1996, 13(3):6-10.
[8]王辉.纳米颗粒在振动流化床中的聚团流态化研究[D].长沙:中南大学, 2010
[9] Noda K, Mawatari Y, Uchida S. Flow patterns of fine particles in a vibrated fluidized bed under atmospheric or reduced pressure[J].Powder Technology, 1998, 99:11-14.
[10] Tahmasebpoor M, de Mratin L, Talebi M, et al. The role of the hydrogen bond in dense nanoparticle gas suspensions[J]. Physical Chemistry Chemical Physics:PCCP, 2013, 15:5788-5793.