Structural Properties and Filter Loading Characteristics of Soot Agglomerates
Structural Properties and Filter Loading Characteristics of Soot Agglomerates
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DOI：
10.1080/02786820903131081
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发表时间：
2009-01-01
影响因子：
5.2
通讯作者：
Pui, David Y. H.
中科院分区：
文献类型：
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作者：
Kim, Seong C.;Wang, Jing;Pui, David Y. H.
纳米颗粒团聚体在大气科学、空气污染和粉末材料制造中普遍存在，但与球形颗粒相比，纳米颗粒团聚体过滤的研究仍然很少。我们研究了碳烟纳米颗粒团聚在纤维空气滤料上的负载情况。以丙烷气体为燃料，以压缩空气为氧化剂/鞘的扩散燃烧器产生了碳烟结块。确定其数目分布模式为120 nm。用差示迁移率分析仪(DMA)-气溶胶粒子质量分析仪(APM)测量了团聚体的质量与迁移率大小的关系，得到的质量-迁移率指数为1.9+/-0.1。通过透射电子显微镜观察发现，团聚体中一次粒子的平均直径为28 nm，几何标准偏差为1.26。在玻璃纤维滤料上进行了面速为10 cm/S的加载实验。压力降随装填质量的增加而近似线性增加。利用滤饼质量和滤饼厚度计算了滤饼的孔隙率，平均为0.95。我们发现，Endo等人的模型。(1998)的滤饼装载适用于烟尘团聚装载。滤饼可以认为是由煤烟凝聚体中的初级颗粒形成的，凝聚体一旦沉积在滤饼中就无法区分。当在Endo等人的模型中使用初级颗粒的尺寸分布时。实验结果与计算结果吻合较好。
Nanoparticle agglomerates are pervasive in atmospheric sciences, air pollution, and manufacturing of powdered materials, yet studies for filtration of nanoparticle agglomerates are still scarce compared to those for spherical particles. We investigated loading of soot nanoparticle agglomerates on fibrous air filter media. The soot agglomerates were generated from a diffusion burner with propane gas as fuel and compressed air as oxidant/sheath. The mode of the number distribution was determined to be 120 nm. A Differential Mobility Analyzer (DMA)-Aerosol Particle Mass Analyzer (APM) system was used to measure the mass of agglomerates as a function of the mobility size, which gave a mass-mobility exponent of 1.9 +/- 0.1. Using transmission electron microscopy (TEM), we found that the primary particles in the agglomerates had a mean diameter of 28 nm with a geometric standard deviation of 1.26. Loading experiments were carried out with the face velocity of 10 cm/s on a fiberglass filter media. The pressure drop increased approximately linearly with the loading mass. The porosity of the cakes was calculated using cake mass and cake thickness, and the average cake porosity was 0.95. We found that the model of Endo et al. (1998) for cake loading was applicable to soot agglomerate loading. The cake could be regarded as formed by primary particles in soot agglomerates, and agglomerates are indistinguishable once deposited in the cake. When the size distribution of the primary particles was used in the model of Endo et al. good agreement between the experimental and computed results was obtained.