微米木纤维纹孔对超微粒子稳态捕集效率的模拟

Simulation of steady collection efficiency of micron wood fiber pits on ultrafine particles

微米木纤维纹孔对柴油车排放的动力学当量直径为.01～1μm的超微粒子具有较强的吸附作用，可有效降低柴油车尾气中PM2.5的排放量。利用微粒浓度控制方程及纤维捕集理论，将纹孔周围的捕集介质假设为圆柱体，对微米木纤维纹孔处的稳态捕集效率进行数值分析。结果表明：微米木纤维对直径为.4～0.6μm的粒子捕集效率相对较低，对其他粒径粒子的捕集效率较高，其中对粒径趋近于.01μm微粒的捕集效率可达％以上，对柴油车超微粒子的捕集有显著作用。在捕集效率的影响因素中，表面渗流速度的降低和管胞壁厚的增加都会提高木纤维的过滤效率，而排气温度对捕集效率的影响较小，可忽略不计。

Micron wood fiber pits have a strong adsorption to ultrafine particles exhausted from diesel vehicles with the kinetic diameter ranging from 0.01μm to 1μm, which can effectively reduce emissions of diesel vehicles PM2.5 . Making use of equations of particle concentration as well as the fiber collection theory, collection media around the pits were sup-posed into cylinders, and numerical analysis was carried out on the steady collection efficiency of micron wood fiber pits. The results show that micron wood fibers have a low collection efficiency to particles with the diameter from 0.4 μm to 0.6 μm, while they have a much higher collection efficiency to those particles in other sizes;among those particles with the diameter of 0.01 μm the collection efficiency of micron wood fibers can reach up to 90%, who plays a significant role on collecting ultrafine particles of diesel vehicles.Among all the factors on collection efficiency, reduction of surface seepage velocity and increase of the tracheid wall thickness would help improving the filtration efficiency, while the ex-haust gas temperature has little effect on collection efficiency, which can totally be ignored.