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Effect of Fiber on PM2.5 Filtration Performance
With the rapid development of my country's industrialization, there are respirable particles with a diameter of less than or equal to 2.5 in the residues discharged from combustion in the process of daily power generation, fuel combustion in industrial and mining enterprises, vehicle exhaust emissions, and smoke emission from smoking.μThe fine particulate matter of m (referred to as PM2.5) can be used as the carrier of other pollutants, enriching toxic heavy metals, organic pollutants, bacteria, acid oxides, etc. Particulate matter can damage respiratory function, cause inflammation, asthma and other respiratory diseases, increase the morbidity and mortality of heart disease, and have potential carcinogenicity. It is of great significance to study how to effectively remove PM2.5 in industrial production and life [2-4]. The current related research shows that the fiber filtration method has a better effect on intercepting PM2.5, so this paper analyzes its influence on the PM2.5 filtration performance from the aspects of single fiber and fiber aggregate. Many scholars at home and abroad have studied fibers in fiber filter media based on two-dimensional models [5-7], but the fibers of actual fiber filter media are randomly distributed in three dimensions. Baumgartner et al. [8] carried out three-dimensional numerical simulation of multiphase dispersed aerosol particles and proposed the concept of deposition spread on filter fibers. Fotovati et al. [9] studied the cross-sectional shape of single fiber filament by CFD simulation method, and analyzed its filtration performance. In this paper, 3D modeling is used for both single fibers and aggregates. Among them, since triangular section fibers are widely used in filtration [10-11], the establishment of different sizes of single fibers“Y”The models with circular section and circular section were compared to analyze the influence of different linear density of monofilament, flue gas flow rate and particulate matter concentration on PM2.5 filtration performance, and obtained the motion law of PM2.5 particulate matter and the velocity distribution of flue gas surrounding fibers law. Considering that the fiber with circular cross section is the research object in the classical filtration theory, and the complexity of the shaped fiber body in modeling, the cylindrical fiber body is used to analyze the linear density, porosity, particle concentration and suction speed of the fiber body Effects on PM2.5 filtration performance. The fibers in the fiber aggregate are randomly distributed, simulating the gas-solid two-phase flow inside, and the Euler method is used to deal with the gas field, and the Lagrange method is used to deal with the discrete particle field. Comparing the experimental data with the numerical simulation results can not only verify the reliability and rationality of the numerical simulation, but also provide a certain reference for the selection of the shape and size of the filter fiber and the optimization of the internal structure of the aggregate in the future, so as to go further. to improve filtration efficiency. 1 Experimental part 1.1 The experimental method of single fiber yarn The single fiber yarn under different working conditions is fixed on the small bracket along the vertical airflow direction, and the fiber yarn is photographed under the microscope every 1 min at the observation point. The photo of the image is binarized, that is, the gray value of the pixel on the image is set to 0 or 255, and the total pixel value of each image remains unchanged. If the filaments are attached by particles, the pixel value of the corresponding point will change. Finally, the number of black dots covered by particles is counted, and the ratio of this value to the number of pixels occupied by fibers is the coverage of particles, which can be used as a reference for studying the filtration performance of single fibers. 1.2 Experimental conditions of single fiber filaments Since the smoke generated during the combustion of cigarettes includes mainstream smoke aerosols during inhalation and side-flow smoke aerosols during smoldering (static combustion), smoke aerosols are used in the experiment. particles, and the concentration of particulate matter produced by a single cigarette during static combustion was measured by ELPI. Among them, the trilobal fiber filaments of the cigarette fiber filter are mostly 120 at the cross-links of the two slender leaves.°Included angle [12], randomly select 20 filaments, measure the diameters of their inscribed circle and circumscribed circle, and obtain different sizes of filaments.“Y”The monofilaments are shown in Figure 1. The single fiber filaments of different sizes and linear densities were placed under the conditions of different particle concentrations and flue gas flow rates for experiments. The experimental conditions are shown in Table 1. The linear density of monofilament has its own definition, and its physical meaning refers to the mass (g) of a 1000 m long monofilament, in tex. 1.3 Experimental results of single fiber filaments 1.3.1 Influence of linear density on particle filtration performance
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