多流道微流体惯性冲击器过滤性能的模拟计算

Numerical Simulation on Filtration Performance of Multi-channel Microfluidic Inertial Impactor

核电厂安全壳内放射性气溶胶的过滤效率是影响其周围环境放射性水平的重要指标。目前仅有关于单流道微流体惯性冲击器过滤效率的研究。多流道微流体惯性冲击器的主要过滤部件为中部有110°转折角的126个流道,通过FLUENT软件模拟计算1~5 m/s空气流速下多流道微流体惯性冲击器内部空气流场,并利用DPM (Discrete Phase Model)模拟0. 5~7. 0μm粒径的气溶胶粒子轨迹,对冲击器中部过滤效率与整体过滤效率进行比较分析。结果表明粒子过滤效率随粒径和入口流速的增大而增大。入口流速大于2 m/s时对安全壳内气溶胶粒子过滤效率超过90%。当气溶胶粒子粒径小于4μm时,多流道微流体惯性冲击器上方入口圆筒底面与下方出口圆筒内壁面可促进过滤效率的提高。出口圆筒的长度可以缩短至现有长度的1/2,从而减小冲击器的整体尺寸。

The filtration efficiency of radioactive aerosols in the containment of nuclear power plants is an important indicator of the level of radioactivity in their surrounding environment.However,research has been limited to the filtration efficiency of single-channel microfluidic inertial impactors.The main filter component of the multi-channel microfluidic inertial impactor has 126 flow channels with a 110°turning angle in the middle.It simulated the internal air flow field of multi-channel microfluidic inertial impactor at 1~5 m/s air velocity by FLUENT and the aerosol particle trajectory of particle with 0.5~7.0μm diameter by Discrete Phase Model the(DPM).The filtration efficiency of total geometry and the middle of the impactor are compared and analyzed.The results show the particle filtration efficiency increases as the particle size and inlet flow rate increase.When the inlet flow rate is greater than 2 m/s,the filtration efficiency of the aerosol particles in the containment is over 90%.When the particle size of the aerosol particles is less than 4μm,the bottom surface of the inlet cylinder and the inner wall of the lower outlet cylinder of the multi-channel microfluidic inertial impactor can improve the filtration efficiency.The length of the outlet cylinder can be shortened to half of the existing length,thus reducing the overall size of the impactor.