Efficiency of aerosol filters made of ultrafine polydisperse fibres

Kirsh, A. A.; Stechkina, I. B.; Fuchs, N. A.

doi:10.1016/0021-8502(75)90004-x

Cited by 55 publications

(20 citation statements)

References 8 publications

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“…Investigation with silver nanoparticles in charge equilibrium with sizes from 3 to 20 nm in diameter (Kim et al 2007) show however no indication of the thermal rebound for the filter used, yet measurements down to 3 nm were only possible for one filter due to counting efficiency issues. Studies of nanoparticle filtration with electrospun polymer fibers with a narrow size distribution in the particle size range above 10 nm in diameter (Yun et al 2007) did not indicate any substantial differences for charged and uncharged particles and show a good agreement with the classical filtration theory (Kirsh et al 1975). However, the same authors reported much higher experimentally measured penetration of nanoparticles when compared to the classical theory in the case of a glass HEPA filter with a broad fiber diameter distribution.…”

Section: Introductionmentioning

confidence: 71%

Penetration of Monodisperse, Singly Charged Nanoparticles through Polydisperse Fibrous Filters

Podgórski

Maisser

Szymanski

et al. 2011

Aerosol Science and Technology

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The article presents experimental results and theoretical analysis of aerosol nanoparticle penetration through fibrous filters with a broad fiber diameter distribution. Four fibrous filters were produced using the melt-blown technique. The analysis of the filters' SEM images indicated that they had log-normal fiber diameter distribution. Five kinds of proteins and two types of silica particles were generated by electrospraying and were then classified using a Parallel Differential Mobility Analyzer to obtain well-defined, monodisperse, singly charged challenge aerosols with diameters ranging from 6.3 to 27.2 nm. Particle penetration through the filters was determined using a water-based CPC. Experimental results were compared first with predictions derived from the classical theory of aerosol filtration. It is demonstrated that it is inappropriate to apply it to the arithmetic mean fiber diameter, as this results in turn in a huge underestimation of nanoparticle penetration. A better, but still unsatisfactory agreement is observed when that theory was used together with the pressure drop equivalent fiber diameter or when the Kirsch model of nonuniform fibrous media was applied. We show that the classical theory applied to any fixed fiber diameter predicts a stronger dependence of nanoparticle penetration on the Peclet number as compared to experimental data. All these observations were successfully explained by using our original partially segregated flow model that accounts for the filter fiber diameter distribution. It was found that the parameter of aerosol segregation intensity inside inhomogeneous filters increases with the increase in particle size, when the convective transport becomes more pronounced in comparison to the diffusive one.

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Section: Introductionmentioning

confidence: 71%

Penetration of Monodisperse, Singly Charged Nanoparticles through Polydisperse Fibrous Filters

Podgórski

Maisser

Szymanski

et al. 2011

Aerosol Science and Technology

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“…As seen in this figure, the experimental pressure drops are in fairly good agreement except the mixing fraction of 5% and 20%. The discrepancy between the predicted and the experimental data represent the degree of inhomogeneity of fibers, which was introduced by Kirsch et al (1975) for accounting the inhomogeneous packing of fibers and the orientation of fibers in filter media in predicting the collection efficiency of a filter. For mixed fiber filters we introduced the inhomogeneity factor which is the ratio of theoretical pressure drop predicted by Eqs.…”

Section: Prediction Of Filtration Performance Of Mixed Fiber Filtersmentioning

confidence: 99%

“…Matulevicius et al (2014) experimentally measured the collection performance of nanofiber filter media fabricated by electrospinning of polyamide, and reported that the filter with finer fibers had a high collection efficiency and a high quality factor. Sambaer et al (2014) and Podgorski et al (2011) introduced the inhomogeneity factor in the prediction of collection efficiency of a laminated nanofiber filter, which was originally proposed by Kirsch et al (1975), and reported that the predicted collection efficiency agreed well with the experimental data by the correction with the inhomogeneity factor. They also reported that the inhomogeneity factor of nanofiber filter was high compared to HEPA filters.…”

Section: Introductionmentioning

confidence: 98%

Filtration Properties of Nanofiber/Microfiber Mixed Filter and Prediction of its Performance

Choi

Kumita

Hayashi

et al. 2017

Aerosol Air Qual. Res.

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There is an increasing demand of air filters with a high collection performance, i.e., high collection efficiency and low pressure drop, for the application to indoor air cleaning. Air filters consisting of nanofibers have attracted great interests since they may have a low pressure drop because of slip flow effect and high collection efficiency due to interception. Although various nanofiber filters are available on the market, their collection performance is not as high as expected by the conventional filtration theory because non-uniform packing of fibers plays a significant role. In the present work, the collection performance of nanofiber (780 nm) and microfiber (11.2 µm) mixed filters with various mixing fractions was studied in order to maximize the quality factor of filter, q F , as a function of mixing fraction of nanofibers. The collection performance of mixed fiber filters was predicted by using theoretical equations reported by Bao et al. (1998) for bimodal distribution of fibers. As a result, it was found that the mixed fiber filters had a uniform fiber packing compared to laminated filters and that the collection efficiency was well predicted by introducing the inhomogeneity factor calculated for the filter consisting of two distinct fiber sizes. Furthermore, we found that the mixed fiber filter with the nanofiber mixing fraction of 5% in mass had the highest quality factor.

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“…The particle penetration, P is converted to the single fiber efficiency, Z, given by eq 4 (Kirsh et al, 1975). Figure 8 shows the experimental single fiber efficiency of an ethanol soaked electrospun filter and that of a micrometer-sized filter, plotted as a function of Peclet number:…”

Section: Filtration Performancementioning

confidence: 99%

Preparation of electrospun polyurethane filter media and their collection mechanisms for ultrafine particles

Choi

Kim

et al. 2013

Journal of the Air & Waste Management Association

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Electrospinning is a simple and versatile process to produce polymer nanofibers, which are useful for ultrafine particle filtration. In this study, a polyurethane filter with an average fiber diameter of 150-250 nm was prepared through the electrospinning process and its filtration characteristics were investigated. We found that the electrospun fiber diameter was highly dependent on the polyurethane concentration, electric field, and tip-to-collector distance. As the polyurethane concentration, electric field, and tip-tocollector distance under the same electric field increased, the fiber diameter increased. We also found that the produced filter media had a minimum collection efficiency at particles sizes from 80 to 100 nm, which implies an electrostatic attraction between the filter and the test particles. Furthermore, we observed that interception was a predominant collection mechanism at Peclet numbers higher than 10 in nanofiber filtration for ultrafine particles.Implications: A polyurethane nanofiber filter with excellent mechanical properties was prepared, and the effect of operating conditions on fiber morphology was examined. The filter fabricated by an electrospinning process is charged and has high filtration efficiency due to electrostatic force. Therefore, it can be a good alternative to control hazardous ultrafine particles.

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Efficiency of aerosol filters made of ultrafine polydisperse fibres

Cited by 55 publications

References 8 publications

Penetration of Monodisperse, Singly Charged Nanoparticles through Polydisperse Fibrous Filters

Penetration of Monodisperse, Singly Charged Nanoparticles through Polydisperse Fibrous Filters

Filtration Properties of Nanofiber/Microfiber Mixed Filter and Prediction of its Performance

Preparation of electrospun polyurethane filter media and their collection mechanisms for ultrafine particles

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