线板式静电设备内微液滴输运特性研究

Numerical simulation on transport characteristics of micro-droplets in wire-plate electrostatic equipments

施加外电场可以提高循环冷却水回收效率,因此研究静电设备内微小液滴的输运特性及其影响因素具有重要的工程意义。采用双向耦合粒子追踪方式,利用k-??湍流模型并根据动量方程求解速度场下的曳力;采用电流连续性方程和电势泊松方程求解静电场,基于粒子随机入口模型,优化不同粒径电荷数,研究在低雷诺数湍流和电场作用下的液滴输运行为、静电设备电势、电场强度分布和液滴的运行轨迹。结果表明:液滴粒径越小越容易受到湍流气流影响,滑移距离增加,收集效率降低;随着气流速度降低,液滴在设备内荷电和运行时间增多,滑移距离降低,收集效率增加;入口电势直接影响液滴的饱和电荷数,特别对于粒径较小的液滴,饱和电荷数降低,收集效率越差。因此,提高工作电压、降低收集板间距可以提高整体饱和电荷数,选择合理的气流速度可以提高循环冷却水收集效率。

The applied external electric field can improve the recovery efficiency of circulating cooling water, so it is necessary to analyze the transport characteristics and influencing factors of micro-droplets in electrostatic equipments. In this paper, the drag force under the velocity field is solved by using the turbulent model and the momentum equation. The electric field distribution was solved by the current continuity equation and Poisson equation. The transport characteristics and trajectories of the droplets and the distribution of electric potential field and intensity in electrostatic equipment sare studied under electric field with low Reynolds number turbulence. The results show that, micro-droplets with smaller diameter are more likely affected by the turbulent air flow, resulting in a longer slip distance and then the collecting efficiency will be reduced in the electrostatic equipments. With the decrease of airflow velocity, the electric charging and flowing time of the micro-droplets in the equipments increase and the collection efficiency of the micro-droplets in the electrostatic equipments becomes larger. In fact, the inlet electric potential directly affects the saturation charge number of the micro-droplets, especially for the droplets with a smaller diameter, the lower the saturated charge number and the lower the collection efficiency. Therefore, the collection efficiency of the circulating cooling water can be improved by increasing the working voltage and decreasing the distance between the collecting plates and selecting a reasonable airflow velocity.