Effect of mesoscale inhomogeneity and fibers size distribution on the initial stage of deep-bed filtration process

Przekop, Rafał; Jackiewicz, A.

doi:10.1016/j.jaerosci.2020.105522

Cited by 13 publications

(8 citation statements)

References 28 publications

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“…Figure a–b gives a comparison of the theoretically predicted filtration efficiency based on different equivalent fiber diameters with the experimental results of Bai et al . and Przekop et al It can be clearly seen that the theoretical prediction of the equivalent fiber diameter calculated based on the flow field theory for fibrous filtration efficiency gives the best fit with experimental results.…”

Section: Resultsmentioning

confidence: 75%

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Probing the Effective Diffusion Coefficient and Filtration Performance of Micro/Nanofibrous Composite Layered Filters

Bai

Qian

Fan

et al. 2021

Ind. Eng. Chem. Res.

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Diffusion is an important filtration mechanism of fibrous filters for removing fine particles from gas streams. An analytical model is proposed in this work, based on fractal theory, to quantify the effective diffusion coefficient (EDC) across micro/nanofibrous filters with a layered structure. To show the influence of macroscopic parameters of fibrous filters on EDC, the present models are expressed in terms of fiber diameter. Polyacrylonitrile (PAN) nanofibers were prepared by electrospinning on melt-blown polypropylene (PP) microfiber filter materials to form micro/nanofibrous filters. To validate this model, a three-dimensional (3D) fiber model with physical parameters of the samples was reconstructed using the GeoDict code, and the Brownian movement of nanoparticles was simulated to calculate the EDC. Two kinds of pore size distributions for the layer-structured fibrous filters have been identified, which also shows the internal heterogeneity of the filter media. With decreasing fiber diameter, the tortuosity of the pore channel increases, while the EDC decreases. Compared with the numerical simulation and the experimental data reported in the literature, the current model gives a better theoretical prediction. In addition, the diffusion mechanism in classical filtration theory was modified to reduce the deviation between theoretical prediction and experimental results.

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Section: Resultsmentioning

confidence: 75%

“…Comparison of theoretically predicted filtration efficiency based on different equivalent fiber diameters with experimental results. , …”

Section: Resultsmentioning

confidence: 99%

Probing the Effective Diffusion Coefficient and Filtration Performance of Micro/Nanofibrous Composite Layered Filters

Bai

Qian

Fan

et al. 2021

Ind. Eng. Chem. Res.

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show abstract

“…It has been reported that particles in a nonuniform filter vary in moving velocity depending on the local structure characteristic. [44,45] A quality factor that takes pressure drop and filtration efficiency into account was used to evaluate filter performance…”

Section: Air Filtration Performance Of Single-layer Nanofibrous Membranesmentioning

confidence: 99%

Improvement of Air Filtration Performance Using Nanofibrous Membranes with a Periodic Variation in Packing Density

Liu

Shao

Wang

et al. 2021

Adv Materials Inter

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particulate matter (particle size > 10 µm), inhalable particulate matter (particle size < 10 µm), and fine particulate matter (PM 2.5 , equivalent diameter < 2.5 µm). [1] PM 2.5 particles are particularly harmful because they can be inhaled into the lungs and even enter the blood circulatory system, causing health issues. [2] PM 2.5 particles are also a good carrier of bacteria and viruses, resulting in the transmission of diseases, such as COVID-19. [3] Filtration with a filter is an effective method to remove these harmful particles and prevent the diseases from spreading.The removal mechanism of fibrous filters for these tiny particles mainly includes inertial collision, [4,5] direct interception, [6] diffusion effect, [7] gravity sedimentation, [8] and electrostatic attraction. [9] Nanofibrous filters have outstanding filtration efficiency due to the fine fiber diameters and high specific surface areas. [10] In addition, nanofibers have lower pressure drop due to the "slip effect" of their unique fiber diameter size, similar to the mean air molecule free path, reducing the airflow resistance. [11] Hence, nanofibers are widely used in air filtration, especially in air filters, [12][13][14] ventilating and air conditioning filters, [15] and masks. [16] Xia et al. [17] compared 122 nanofibrous filters with conventional heating, ventilation, and air-conditioning (HVAC) filters and showed that nanofiber filters had a higher quality factor than the conventional filters because of nanofibers' "slip effect."Considerable research has been devoted to understanding the structural parameters of nanofibers and their effect on filtration performance. For example, Wang et al. [18] studied the influence of nanofiber morphology on filtration performance. Zhang et al. [19] reported a pore size gradient combination of different nanofibrous membranes, which showed a filtration efficiency of 99.992% for 300 nm particles at a low-pressure drop. Li et al. [20] proposed a mathematical relationship between filtration efficiency and nanofibrous pore size. Bian et al. [21] established a semiempirical model to predict the influence of nanofiber diameter, membrane thickness, and packing density on the pressure drop of nanofibrous filters. Most studies have been based on nanofiber membranes with a homogenous distribution of nanofibers along the membrane.This study reports a patterned nanofibrous membrane and its novel filtration performance. The nanofibers are prepared using an electrospinning technique, and the nanofibers are collected on a commercial nonwoven fabric covering a roller collector, which is prepared using a metal sheet with a round hole array. The nanofibers collected on the metal surface have a much denser structure than those in the hole areas. As a result, the patterned nanofibrous membrane has a different filtration performance (lower pressure drop and filtration efficiency) from the uniform nanofiber membrane, prepared under the same condition but using a smooth roller collector. When two layers of this patterned nanof...

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“…The influence of structure regularity and fiber diameter distribution on the filtration performance was studied by Przekop . Four different fiber models are shown in Figure panels a, b, c, and d, respectively.…”

Section: Effect Of Microstructure On Filtration Efficiencymentioning

confidence: 99%

Section: Effect Of Microstructure On Filtration Efficiencymentioning

confidence: 99%

Theoretical Model of Single Fiber Efficiency and the Effect of Microstructure on Fibrous Filtration Performance: A Review

Bai

Qian

Fan

et al. 2020

Ind. Eng. Chem. Res.

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Fibrous filters are widely used in manufacturing and separation industries to remove aerosol particles produced in the production process. However, due to the complex internal structure of fibrous filters, there are still some problems to be investigated. In the first part of this review, the different theoretical analyses of the flow field distribution around the fiber is summarized. In a comparison of the various theoretical models of flow fields with the simulation results, the Kuwabara-Happel flow field model has the best applicability. The theoretical models of single fiber filtration by five mechanisms: diffusion, interception, inertial impaction, gravity settling, and electrostatic effects are summarized. One of the other outstanding questions is the effect of fibrous microstructure characteristics on filtration efficiencies, such as the composite layer structure, the heterogeneity of the fibrous filters, and the fiber orientation. Finally, critical gaps in the literature and necessary directions for future investigations are also given.

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Effect of mesoscale inhomogeneity and fibers size distribution on the initial stage of deep-bed filtration process

Cited by 13 publications

References 28 publications

Probing the Effective Diffusion Coefficient and Filtration Performance of Micro/Nanofibrous Composite Layered Filters

Probing the Effective Diffusion Coefficient and Filtration Performance of Micro/Nanofibrous Composite Layered Filters

Improvement of Air Filtration Performance Using Nanofibrous Membranes with a Periodic Variation in Packing Density

Theoretical Model of Single Fiber Efficiency and the Effect of Microstructure on Fibrous Filtration Performance: A Review

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