纤维过滤介质结构模型的三维重建及其过滤特性的数值模拟
发布时间：2019-06-10 07:05
【摘要】：工业生产中产生的粉尘颗粒会对环境和人体健康造成危害，随着国家对污染物排放标准的逐渐提高以及人们环保意识的增强，对空气中的微细颗粒物进行有效的过滤显得至关重要。纤维过滤材料对颗粒物的过滤能达到国家标准的要求，因此对其过滤性能进行研究可以为过滤介质的优化提供依据。 本文通过扫描电镜成像（Scanning Electron Microscopy，SEM）获得纤维过滤介质的二维截面图像，利用Matlab对所得图像进行处理，编写重建三维过滤介质所需的程序，并与Gambit结合，最终生成以实际过滤介质为基础的三维模型；通过改变模型的结构参数，包括纤维直径df、纤维的偏离距离L和前后延伸长度H三个参数，利用响应曲面法分析结构参数和迎面风速对过滤介质气相场、固体体积分数（Solid Volume Fraction, SVF）和压力损失的影响，并与经验模型的结果进行比较；通过CFD-DEM耦合技术，模拟纤维过滤介质内部的气-固两相流动，研究纤维与颗粒的特性对颗粒沉积和团聚的影响，改变过滤介质的结构参数以分析其对介质过滤特性（包括压力损失和过滤效率）的影响，结果表明： （1）本文通过Matlab与Gambit结合重建出的三维过滤介质模型是以实际过滤介质的二维图像为基础，重建的模型与实际的过滤介质具有很大的关联性，对这些模型进行研究为推测实际过滤介质的过滤性能提供了依据。 （2）纤维直径是影响过滤介质SVF和气相场压力损失的显著因素，两者都随着纤维直径的增大而增大。纤维的偏离距离L和前后距离H对SVF的影响很小，但压力损失随L和H的增大先增大后减小，在两者为中水平时达到最大值。 （3）纤维过滤介质内部的气相流场呈现不均匀性。气相场压力损失随着SVF和迎面风速的增大而增大，SVF相同时，不同结构参数的过滤介质压力损失存在差别，表明过滤介质的压力损失与纤维的排列方式有关。此外，压力损失的模拟值与Davies实验关联式吻合的较好，误差小于5%，说明本文的纤维过滤介质数值计算模型是合理的，同时进行的过滤介质内部气相流场的数值模拟也是可信的。 （4）利用CFD-DEM耦合方法对纤维过滤介质内部的气-固两相流动进行数值模拟，然后研究过滤介质结构参数的变化对其压力损失和过滤效率以及颗粒沉积和团聚的影响，过滤介质效率的模拟值与经验关联式计算值总体趋势一致，表明本文的模型是合理的。通过颗粒在纤维上沉积与团聚的模拟图与实验观测图对比可知，利用CFD-DEM研究颗粒在纤维介质表面沉积与团聚是可行的。 （5）在介质过滤阶段，颗粒在纤维介质表面沉积的质量随着过滤时间的增加而增加，当纤维偏离距离L和延伸长度H不变，纤维直径df增大时，表面过滤的贡献较大。 （6）相对于气相流场，不同工况下纤维过滤介质在过滤颗粒时的压力损失均增加，且呈现指数增长的趋势，表明颗粒的沉积改变了过滤介质内部的孔隙率，从而对介质的压力损失产生影响。纤维直径df是影响过滤介质总压力损失的主要因素，，随着df的增加，总压力损失增大。纤维偏离距离L和延伸长度H变化时，纤维的排列方式发生了变化，过滤介质的总压力损失随具体的工况而定。总体而言，纤维分布越密集，介质的总压力损失越大。纤维过滤介质的过滤效率随着纤维偏离距离L的增加而减小，纤维延伸长度H的变化对效率基本无影响。
[Abstract]:The dust particles produced in the industrial production can be harmful to the environment and the human health, and the effective filtration of the fine particles in the air is of great importance as the country's gradual improvement of the emission standard of the pollutants and the enhancement of the environmental awareness of the people. The filtering performance of the fiber filter material can meet the requirements of the national standard, so the filtering performance of the fiber filter material can provide the basis for the optimization of the filter medium. In this paper, two-dimensional section images of fiber filter media were obtained by scanning electron microscopy (SEM). The obtained images were processed by using Matlab. The program needed to reconstruct the three-dimensional filter media was written and combined with Gamit. The three-dimensional model based on the actual filter media was finally generated. By changing the structural parameters of the model, including the fiber diameter df, the deviation distance L of the fiber and the front and rear extension length H, the solid volume fraction (SVF) and the pressure loss are analyzed by using the response surface method to analyze the structural parameters and the head-on wind speed. In response to the results of the empirical model, the gas-solid two-phase flow in the fiber filtration media was simulated by the CFD-DEM coupling technique, and the properties of the fibers and the particles were studied. In response, the structural parameters of the filter medium are changed to analyze its effect on the filter characteristics of the medium, including pressure loss and filtration efficiency, and the results table (1) The three-dimensional filter media model reconstructed from the combination of Matlab and Gamit is the two-dimensional image of the actual filter media. On the basis of which, the reconstructed model has a great relevance to the actual filter media, and the research of these models is to estimate the filtering performance of the actual filter media. (2) The fiber diameter is a significant factor that affects the pressure loss of the SVF and gas phase fields of the filter medium, both of which follow the diameter of the fiber The deviation distance L of the fiber and the front-to-back distance H have little effect on the SVF, but the pressure loss decreases with the increase of L and H, the maximum value is reached. (3) the gas phase flow inside the fiber filter medium If the pressure loss of the gas phase increases with the increase of the SVF and the head-on wind speed, the pressure loss of the filter media of different structural parameters is different when the SVF is the same, indicating the pressure loss and the fiber of the filter medium. In addition, the simulated value of pressure loss is well matched with Davies' experimental correlation formula, and the error is less than 5%. The numerical calculation model of the fiber filter media in this paper is reasonable, and the numerical value of the gas-phase flow field inside the filtration media The simulation is also credible. (4) The gas-solid two-phase flow in the fiber filter media is numerically simulated by means of the CFD-DEM coupling method, and the pressure loss and the filtration efficiency of the filter media are studied. The effect of particle deposition and agglomeration is that the simulation value of the efficiency of the filter medium is consistent with the general trend of the empirical correlation formula. The model of this paper is reasonable. Through the comparison between the simulation of the deposition and the agglomeration of the particles on the fiber and the experimental observation, the research of the particle on the surface of the fiber medium with the CFD-DEM the deposition and agglomeration are feasible. (5) the mass of the particles on the surface of the fiber medium increases with the increase of the filtration time during the media filtration stage, the fiber diameter df increases when the fiber deviates from the distance l and the extension length h, On the other hand, the contribution of surface filtration is large. (6) In contrast to the gas-phase flow field, the pressure loss of the fiber filter media in the filter particles is increased, and the trend of exponential growth is presented, indicating that the deposition of the particles changes the porosity inside the filter medium, and the fiber diameter df is the main factor that affects the total pressure loss of the filter media, the increase in df increases the total pressure loss. the arrangement of the fibers changes when the distance l and the extension length h change, and the filter media The total pressure loss varies with the specific operating conditions. Overall, the more fiber distribution the larger the total pressure loss of the medium, the larger the filtration efficiency of the fiber filter media decreases with the increase of the fiber offset distance l, the fiber extension length,
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU834
本文编号：2496271
[Abstract]:The dust particles produced in the industrial production can be harmful to the environment and the human health, and the effective filtration of the fine particles in the air is of great importance as the country's gradual improvement of the emission standard of the pollutants and the enhancement of the environmental awareness of the people. The filtering performance of the fiber filter material can meet the requirements of the national standard, so the filtering performance of the fiber filter material can provide the basis for the optimization of the filter medium. In this paper, two-dimensional section images of fiber filter media were obtained by scanning electron microscopy (SEM). The obtained images were processed by using Matlab. The program needed to reconstruct the three-dimensional filter media was written and combined with Gamit. The three-dimensional model based on the actual filter media was finally generated. By changing the structural parameters of the model, including the fiber diameter df, the deviation distance L of the fiber and the front and rear extension length H, the solid volume fraction (SVF) and the pressure loss are analyzed by using the response surface method to analyze the structural parameters and the head-on wind speed. In response to the results of the empirical model, the gas-solid two-phase flow in the fiber filtration media was simulated by the CFD-DEM coupling technique, and the properties of the fibers and the particles were studied. In response, the structural parameters of the filter medium are changed to analyze its effect on the filter characteristics of the medium, including pressure loss and filtration efficiency, and the results table (1) The three-dimensional filter media model reconstructed from the combination of Matlab and Gamit is the two-dimensional image of the actual filter media. On the basis of which, the reconstructed model has a great relevance to the actual filter media, and the research of these models is to estimate the filtering performance of the actual filter media. (2) The fiber diameter is a significant factor that affects the pressure loss of the SVF and gas phase fields of the filter medium, both of which follow the diameter of the fiber The deviation distance L of the fiber and the front-to-back distance H have little effect on the SVF, but the pressure loss decreases with the increase of L and H, the maximum value is reached. (3) the gas phase flow inside the fiber filter medium If the pressure loss of the gas phase increases with the increase of the SVF and the head-on wind speed, the pressure loss of the filter media of different structural parameters is different when the SVF is the same, indicating the pressure loss and the fiber of the filter medium. In addition, the simulated value of pressure loss is well matched with Davies' experimental correlation formula, and the error is less than 5%. The numerical calculation model of the fiber filter media in this paper is reasonable, and the numerical value of the gas-phase flow field inside the filtration media The simulation is also credible. (4) The gas-solid two-phase flow in the fiber filter media is numerically simulated by means of the CFD-DEM coupling method, and the pressure loss and the filtration efficiency of the filter media are studied. The effect of particle deposition and agglomeration is that the simulation value of the efficiency of the filter medium is consistent with the general trend of the empirical correlation formula. The model of this paper is reasonable. Through the comparison between the simulation of the deposition and the agglomeration of the particles on the fiber and the experimental observation, the research of the particle on the surface of the fiber medium with the CFD-DEM the deposition and agglomeration are feasible. (5) the mass of the particles on the surface of the fiber medium increases with the increase of the filtration time during the media filtration stage, the fiber diameter df increases when the fiber deviates from the distance l and the extension length h, On the other hand, the contribution of surface filtration is large. (6) In contrast to the gas-phase flow field, the pressure loss of the fiber filter media in the filter particles is increased, and the trend of exponential growth is presented, indicating that the deposition of the particles changes the porosity inside the filter medium, and the fiber diameter df is the main factor that affects the total pressure loss of the filter media, the increase in df increases the total pressure loss. the arrangement of the fibers changes when the distance l and the extension length h change, and the filter media The total pressure loss varies with the specific operating conditions. Overall, the more fiber distribution the larger the total pressure loss of the medium, the larger the filtration efficiency of the fiber filter media decreases with the increase of the fiber offset distance l, the fiber extension length,
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU834
【参考文献】
相关期刊论文 前2条
1 李嘉禄,刘谦;三维编织复合材料中纤维束横截面形状的研究[J];复合材料学报;2001年02期
2 王海刚;钱付平;陈乐端;;基于响应曲面法平纹纤维过滤器过滤性能研究[J];广州大学学报(自然科学版);2010年02期
本文编号：2496271
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