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Gifu, Japan

Nippon Muki Co. | Date: 2013-06-25

An air filter unit has a pleated filter medium with a zigzag shape in which a fibrous filter medium has been folded multiple times. The coefficients of linear expansion of the space-supporting members provided in each of the multiple folded spaces of the pleated filter medium are equal to or greater than the coefficient of linear expansion of the metal filter frame of the filter unit. The linear expansion coefficients of first space-supporting members are smaller than the linear expansion coefficient of a second space-supporting member. The first space-supporting members are provided in side portion regions including both side portions positioned at outermost sides of the pleated filter medium in a second direction perpendicular to the first direction. The second space-supporting member is provided in a central portion region sandwiched between the side portion regions.

Yun K.M.,Hiroshima University | Yun K.M.,KAIST | Suryamas A.B.,Hiroshima University | Iskandar F.,Hiroshima University | And 4 more authors.
Separation and Purification Technology | Year: 2010

Polymer nanofiber mats with various morphology structures (nanofiber, beaded-nanofiber, and composite particle/nanofiber) were prepared by electrospinning for application to aerosol particle filtration. The filtration performance of these polymer nanofiber mats was evaluated based on quality factors generated from measurement of penetration through the filter by sodium chloride (NaCl) aerosol particles ranging from 20 to 300 nm. These filtration test results showed that the quality factors of beaded-nanofiber filter mats were the best, even though the aerosol particle penetration of them was the highest of the morphology structures. The results of the present study show that morphology optimization of polymer nanofibers is an effective method for improvement of filtration performance, and it must be the future direction for development of new filtration media. © 2010 Elsevier B.V. All rights reserved. Source

Bao L.,Nippon Muki Co. | Seki K.,Nippon Muki Co. | Niinuma H.,AAF International B.V. | Otani Y.,Kanazawa University | And 4 more authors.
Separation and Purification Technology | Year: 2016

Slip flow phenomena are of great concern in aerosol filtration because of their ability to develop low-pressure drops and high collection efficiency air filters by using nanofibers. However, it is a difficult task to verify the slip flow effect on the reduction in pressure drop because the inhomogeneity in fiber packing also results in a decrease in pressure drop. In the present work, we propose pressure drop measurements at low pressures to verify the slip flow effect by distinguishing the effects of filter inhomogeneity. We found that the experimental dimensionless drag at low-pressure conditions, which was obtained with correction by the inhomogeneity factor measured at atmospheric pressure, followed the theoretical prediction that includes the slip flow correction (Kirsch and Stechkina, 1978) for both conventional PTFE and newly developed fluororesin nanofiber filter media. Because the dimensionless drags of both nanofiber filters decreased inversely proportional to the Knudsen number, we concluded that these nanofiber filters have low-pressure drops because of slip flow effects. © 2015 Elsevier B.V. All rights reserved. Source

Balgis R.,Hiroshima University | Kartikowati C.W.,Hiroshima University | Ogi T.,Hiroshima University | Gradon L.,Warsaw University of Technology | And 3 more authors.
Chemical Engineering Science | Year: 2015

Straight and bead-free nanofibers were synthesized via electrospinning by adding potassium iodide to a precursor containing polyacrylonitrile dissolved in dimethylformamide. Nano- and submicron-fibers with diameters of 36.5-300. nm were electrospun on the surface of a microfiber mat as the base filter to form a strong multilayer filter. The size of the fibers was controlled by adjusting the electrospinning atmosphere (i.e., temperature and humidity) and polyacrylonitrile and potassium iodide concentrations in the precursor solution. The pressure drop of the prepared multilayer filters was measured simultaneously in an aerosol filtration test using monodispersed aerosol particles of diameter 100. nm. Interestingly, the rate of pressure drop was reduced for filters composed of nanofibers with a diameter of less than 100. nm deposited on the base filter. In this case, the pressure drop was more gradual than was expected for a continuous flow pattern, mainly because of the slip flow effect. Because the thickness of the boundary layer for mass transfer is greater when nanofibers are thinner, the filtration efficiency of these filters was almost constant. Further reduction of the fiber diameter leads to the flow condition entering the free-molecular regime. © 2015 Elsevier Ltd. Source

Ogi T.,Hiroshima University | Ono H.,Hiroshima University | Bao L.,Nippon Muki Co. | Niinuma H.,Nippon Muki Co. | Okuyama K.,Hiroshima University
Kagaku Kogaku Ronbunshu | Year: 2014

Polyacrylonitrile (PAN) nanofibers with various morphological structures were produced by electrospinning by controlling the physicochemical properties (viscosity, surface tension, and electrical conductivity) in the precursor solution. Quantitative evaluation showed that fiber morphology was strongly influenced by precursor viscosity, and the viscosity thresholds affecting fiber morphology (ribbon-like, straight, spindle-like beaded, and beaded) were clarified. Using a monodisperse aerosol, the air filtration performance of filters made with these fibers was evaluated based on quality factors. Filters composed of beaded fiber showed the best quality in the air filtration test. © 2014 The Society of Chemical Engineers, Japan. Source

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