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首页> 外文学位 >Modeling and Numerical Studies of Submicron particle Transport and Filtration with Monolith filters.
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Modeling and Numerical Studies of Submicron particle Transport and Filtration with Monolith filters.

机译：整体过滤器对亚微米级颗粒传输和过滤的建模和数值研究。

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摘要

Aerosol particle filtration is crucial for many industrial and air purification processes. Different types of aerosol particle filters has been developed and utilized in the past few decades. Monolith filter is a new type of filter that fabricated from a single piece of polymer material characterized with small holes on a thin film. Monolith filter has significant potential for submicron aerosol particle filtration, even though the filtration process with this class of filters has not been well studied. Modeling and analysis of transport and filtration process in monolith filters were studied in this thesis.;Based on the filtration process and the repeating geometric structure of a monolith filter, a single channel model and a single unit model were developed respectively, where the drag force, electrostatic force, and Brownian motion are considered as the major forces affecting particle motion. Using a single channel model or a single unit model, numerical studies were performed with Lagrangian particle tracking methodology and a Monte Carlo simulation. Filtration efficiency was estimated by statistics of a group of particles. Simulation results clearly showed a transition of particle capture mechanism from Brownian motion to direction interception when particle diameter increases, resulting with a most penetrating particle size of 100nm to 250nm.;A single unit model was modified and improved based on the comparison with experimental results. The comparison suggests that the original model of Brownian force underestimated particle's Brownian motion, and Van Der Waals force should be considered when a particle is approaching to the surface of a filter. The improved model showed a reasonable agreement with experimental results. The dependency of filtration efficiency on flow rates, channel diameter and applied electric charge on the filter were studied with the improved model.;A preliminary dimensionless study was performed. While an interception parameter characterizes the particle capture due to direct interception, two dimensionless parameters, dimensionless Brownian force and dimensionless electrostatic force, were derived from the dimensionless form of the particle motion equation to characterize the particle motion due to Brownian diffusion and electrostatic force. Simulations suggests that these two dimensionless parameters cannot determine the capture efficiency by themselves. However, it was verified that particle capture due to Brownian diffusion inside a circular channel is dependent on a deposition parameter. Comparison between numerical simulations and traditional asymptotic solutions show that the traditional asymptotic solutions underestimates the filtration efficiency.
机译：气溶胶颗粒过滤对于许多工业和空气净化过程至关重要。在过去的几十年中，已经开发并使用了不同类型的气溶胶颗粒过滤器。整体式过滤器是一种新型的过滤器，由单片聚合物材料制成，其特征是薄膜上有小孔。整体式过滤器对于亚微米气溶胶颗粒过滤具有巨大的潜力，即使对此类过滤器的过滤过程尚未进行充分研究。本文研究了整体式过滤器中运输和过滤过程的建模与分析。;在整体式过滤器的过滤过程和重复几何结构的基础上，分别建立了单通道模型和单一单元模型，并对其阻力进行了研究。静电力和布朗运动被认为是影响粒子运动的主要力。使用单通道模型或单个单元模型，使用拉格朗日粒子跟踪方法和蒙特卡洛模拟进行了数值研究。通过一组颗粒的统计估计过滤效率。仿真结果清楚地表明，当粒径增加时，颗粒捕获机制从布朗运动转变为方向截获，从而使穿透性最强的粒径从100nm变为250nm。;与实验结果进行比较，对单个单元模型进行了修改和改进。比较表明，布朗力的原始模型低估了粒子的布朗运动，当粒子接近过滤器表面时，应考虑范德华力。改进后的模型与实验结果吻合良好。利用改进的模型研究了过滤效率对流速，通道直径和施加在过滤器上的电荷的依赖性。尽管截取参数表征了直接截获引起的粒子捕获，但从粒子运动方程的无量纲形式导出了两个无量纲参数，即无量纲布朗力和无量纲静电力，以表征由布朗扩散和静电力引起的粒子运动。仿真表明，这两个无量纲参数本身无法确定捕获效率。然而，已证实，由于圆形通道内部的布朗扩散而导致的颗粒捕获取决于沉积参数。数值模拟与传统渐近解的比较表明，传统渐近解低估了过滤效率。

著录项

  • 作者

    Wu, Mengbai.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Engineering Mechanical.;Textile Technology.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 153 p.
  • 总页数 153
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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