基于微通道表面带有静电的Monolith过滤器过滤性能的模拟研究

发布时间：2018-01-08 19:23

本文关键词：基于微通道表面带有静电的Monolith过滤器过滤性能的模拟研究　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：高效空气过滤器(HEPA)得到了广泛的推广和普及,是现代洁净系统最主要的末级过滤器。HEPA是衡量一个国家过滤技术发展水平的重要标准。HEPA设备的高效节能和廉价是关键。因此,对低阻高效空气过滤器进行探索性实验研究是进一步挖掘其市场潜力的一个突破点。monolith过滤器是由筛网状介质加工而成,具有形态整齐的多孔结构,流动阻力很小。对于粒径等于或大于孔径的粒子具有绝对过滤能力。而对于能够穿过微孔的亚微米粒子,monolith通道也能表现出很高的过滤能力,使得monolith过滤器成为新型高效空气过滤器发展的一个重要方向。同时,随着微纳米级加工技术的发展,目前核孔膜技术可以生产出孔径达0.015~10μm的微孔薄膜滤料,使得基于微米级通道的monolith过滤器的研究逐渐被重视。然而,目前国内外对于monolith过滤器的理论研究还比较少,通道的过滤机制还不完善,这为monolith过滤器的设计和制造增加了许多麻烦。针对这一情况,本文对monolith过滤器通道的过滤性能作了全面的研究并与传统的纤维过滤器作比较,为设计和制造更加高效经济的空气过滤器提供理论依据。本文采用单通道理论模型分析了表面带有静电的monolith过滤器通道的的过滤性能。首先研究了单个粒子在monolith微通道内的运动特点,结果表明,粒子直径Dp0.1μm时主要受到布朗力和静电力的作用,随着Dp的增大,粒子的运动逐渐由流动阻力主导。接着,本文还研究了气流入口速度和方向,静电力,粒子直径等因素对monolith通道过滤效率的影响,结果表明,当Dp0.1μm时,入口速度u0增大,捕获效率下降很快,u03m/s时,捕获效率接近于0且不再受气溶胶入口速度的影响,粒子的捕获效率随气溶胶入射角度的增大几乎没有变化,而当Dp1μm时,随着u0的增大,通道的捕获效率先减小后增大,粒子的捕获效率随气溶胶入射角度的增大增加十分明显。静电力对monolith通道捕获效率的影响十分显著,研究表明,当粒子直径较小(Dp0.1μm)时,粒子带有与通道异种电荷时通道的捕获效率显著增强。因此采用人工的方法使monolith过滤器表面带有稳定高密度电荷具有重要意义,目前常用的方法是过滤器制造时在通道表面嵌入驻极体。粒子的直径是通道捕获效率最为重要的一个影响因素,随着粒子直径的增大,粒子的运动由主要受到布朗力和静电力的作用逐渐转变成由流动阻力主导。粒子直径Dp在0.01μm~1μm内,通道的捕获效率随着粒子直径的增大先减小后增大,存在一个效率最低值,此时的粒子直径称为最大穿透力直径Dpmax=0.1~0.4μm。本文还对monolith过滤器内粒子沉积位置沿通道的分布规律作了分析,结果表明,大部分的粒子沉积在通道前10%区域,在其他位置沉积较少且分布较均匀,在工程应用中,对于monolith过滤器的清洗应该集中在通道前10%的位置。Dp=0.05μm时,粒子沿通道沉积位置分布与气流入口速度方向关系不大,而当气流入射速度增大时,粒子沿通道沉积位置分布明显向后移动;Dp=0.5μm时,气流进入通道的速度增大和一定角度进入通道均能使粒子的沉积位置向后推移。最后,本文在各方面条件相当的情况下比较了monolith过滤器与传统纤维过滤器的过滤性能,结果表明,在保证气流入口流速相等的情况下,monolith过滤器在对小粒子(Dp0.1μm)具有明显更高的效率;u0=0.1m/s时,纤维过滤器的过滤阻力ΔP=160Pa,monolith过滤器的过滤阻力ΔP=60Pa,约为纤维过滤器的1/3,这再一次证实了monolith过滤器相比于传统纤维过滤器在处理亚微米级粒子具有高效率低能耗的优良特性。
[Abstract]:High efficiency air filter (HEPA) has been widely popularized, is the final filter for the main.HEPA system is an important modern clean energy efficient standard.HEPA equipment to measure a country's level of development of filtering technology and cheap is the key. Therefore, exploratory experimental study is to further tap its potential market a breakthrough. The.Monolith filter is composed of a screen mesh is processed on medium low resistance and high efficiency air filters, with porous structure neat, flow resistance is small. With the absolute filtration ability for particle size is equal to or greater than the diameter of particles. The submicron particles can pass through the pore, the monolith channel can exhibit very high filtration capacity the filter makes monolith become an important direction of new high efficiency air filter development. At the same time, along with the development of micro nano machining technology, the core of Kong Mo The technology can produce microporous membrane pore size was 0.015~10 m, which makes the research of monolith filter based on the micro channel is gradually. However, at home and abroad for the theoretical research of monolith filter is still relatively small, channel filtering mechanism is not perfect, it adds a lot of trouble for the design and fabrication of monolith filter. In view of this situation, the filtering performance of monolith filter channel is studied and compared with the traditional fiber filter, so as to provide theoretical basis for air filter design and manufacture more efficient economy. This paper uses the theoretical model of single channel filter performance monolith filter channel with the electrostatic surface analysis. Movement characteristics first of all, the research of single particle in monolith in the micro channel. The results show that the main force of the particle diameter of Dp0.1 by Brown m and static electricity The role, along with the increase of Dp, the movement of the particles gradually by the flow resistance of LED. Then, this paper also studies the entrance flow velocity and direction of static electricity, influence factors, particle diameter on the monolith channel filter efficiency. The results showed that when Dp0.1 m, entrance velocity of U0 increases, the capture efficiency drops quickly, u03m/s when the impact of capture efficiency is close to 0 and no longer by sol entrance velocity, particle capture efficiency increases with the increase of aerosol incident angle is almost no change, while Dp1 m, with the increase of U0, the channel capture efficiency decreases first and then increases, the particle capture efficiency of aerosol with increasing incident angle increases obviously the influence of static electricity on monolith channel. The trapping efficiency is very significant, research shows that when the particle size is smaller (Dp0.1 m), and the effect of particle with the capture rate of channel charges when channel is significantly enhanced. Therefore. The use of artificial methods to make monolith filter surface has important significance with stable high charge density, the current commonly used method is to filter manufacturing in the channel is embedded on the surface of the electret. The diameter of the particles is the channel capture efficiency of one of the most important factors, with the increase of particle diameter, particle movement by the main force by Brown the static electricity and gradually transformed into the flow resistance. The particle diameter is dominated by Dp in 0.01 m~1 m, the channel capture efficiency increases with the particle diameter decreases first and then increases, there is an efficiency minimum value, the particle diameter is called the maximum penetration diameter of Dpmax=0.1~0.4 M. the position of particle deposition the monolith filter along the channel distribution are analyzed, the results show that the particle deposition in most of the channel before the 10% area, in other locations in the deposition less and more uniform distribution in the industry The application process for cleaning, monolith filter should be focused on the channel position in the top 10%.Dp=0.05 m, the relationship between particle distribution and deposition position along the channel entrance airflow velocity direction is small, and when the incident flow velocity increasing, the particle deposition distribution along the channel was moving to the rear; Dp=0.5 m, the airflow into the channel increase the speed and angle into the channel can make the particle deposition position goes backwards. Finally, this paper compares the performance of monolith filter, filter and traditional fiber filter in all aspects under the same conditions. The results show that the flow velocity is equal to the entrance in that case, the small particle filter in monolith (Dp0.1 m) with much higher efficiency.; u0=0.1m/s, the filtration resistance of delta P=160Pa fiber filter, filtration resistance Delta P=60Pa monolith filter, fiber filter is about 1/3, which once again It is proved that the monolith filter has the excellent characteristics of high efficiency and low energy consumption compared with the traditional fiber filter in the processing of submicron particles.

【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU834.83

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