荷电液滴群捕集非均匀粒径颗粒物的数值模拟

Numerical simulation of polydisperse particles capture by charged droplets

针对荷电液滴群捕集颗粒物过程中系统参数对捕集效率的影响,基于计算流体力学-离散元法(CFD-DEM),数值模拟了荷电液滴群捕集非均匀粒径颗粒物。结果表明:在库仑斥力影响下,液滴群运动过程中不断向外扩展,颗粒物聚集形态不断变化。静电沉积占主导地位时,捕集效率对液滴间距不敏感,液滴间距可以认为是喷雾密度,即除尘效率受喷雾密度影响较小;增大液滴荷电量提升的捕集效率主要来自对粒径小于5μm颗粒物的捕集;液滴粒径对捕集效率的影响较小;液滴速度对单位时间捕集效率影响较小,但降低液滴速度可以延长其扫掠时间,从而提升捕集效率。

A numerical simulation of polydisperse particles capture based on the computational fluid dynamics and discrete element method(CFD-DEM) method was carried out to investigate the effect of system parameters on capture efficiency in the process of particles capture by charged droplets. The results showed that charged droplets continuously expanded outwards due to the droplet-droplet Coulomb repulsion and the agglomeration pattern of particles kept changing. When the electrostatic deposition was dominant, the capture efficiency was not sensitive to the droplet spacing, which could be interpreted as the spray density, i.e. was less affected by the charged spray density;the increase of droplet charge enhanced the capture efficiency mainly from the capture of particles with size less than 5 μm;the droplet size had a negligible effect on the capture efficiency;the droplet velocity had little effect on the capture efficiency per unit time, but reducing the droplet velocity could extend the sweeping time of the droplet, and thus improved the overall capture efficiency.