【摘要】 大气污染治理水平的提高对静电除尘器的净化效率提出更高要求。利用数值模拟设计静电除尘器有助于优化结构和提高性能,而模拟过程中选用的颗粒荷电模型很大程度决定了模拟结果的准确性。通过建立双区静电除尘器电场、流场和颗粒运动模型,计算两种荷电模型下双区静电除尘器内部颗粒运动轨迹,分析荷电模型对荷电区和收尘区内颗粒轨迹的影响。通过两种荷电模型下0. 4μm颗粒和7. 5μm颗粒去除率模拟值与实测值的对比,发现荷电模型导致的模拟值差异随颗粒粒径的减小而增大。定电量模型适用于电场荷电为主的大粒径颗粒,对扩散荷电的忽略使得该模型下小粒径颗粒的模拟去除率远小于实测值。综合考虑电场荷电量和扩散荷电量随时间变化的模型可以很好地反映小粒径颗粒的荷电特性,更适用于对小粒径颗粒荷电行为特征的数值模拟。更多还原

【Abstract】 Improvement of air pollution control raises higher requirements for dust-removal efficiency of electrostatic precipitators( ESP). Designing ESP with numerical simulation is beneficial to structure optimization and performance improvement,while the accuracy of simulation results depends largely on charging models selected in the simulation process. A numerical model was developed for the description of physical process in two-stage ESP,including fluid flow,corona discharge and particle dynamics. Particle tracks in charging part and dust-removal part were calculated and analyzed with two charging models.With the comparison of simulated and experimental values of 0. 4 μm and 7. 5 μm particle removal efficiency,it was found that the gap between simulated values caused by charging model increased with decreasing particle size. Constant charging model is suitable for particles whose field charging is dominant. While its neglection of diffusion charging makes the simulated particle-removal efficiency of fine particles far more less than the measured value. The model assuming both field charging and diffusion charging are functions of time reflects charge characteristics of fine particles well and suits for the simulation process of fine particles.更多还原