“…Figure 3 shows filtration efficiency as a function of air permeability for all investigated samples: an inversely proportional relationship is found between these two properties, as expected. 25 It can also be observed that efficiency increases as fiber diameter decreases, which is also expected. Figure 3.Filtration efficiency E * versus air permeability* for unimodal fiber diameter (UFD) nonwovens.Figure 4.Filtration efficiency E * versus fiber basis length.Figure 5.Filtration efficiency E * versus solid volume fraction (SVF).…”
Section: Resultssupporting
confidence: 62%
“…Lee and Liu 24 and Davies 25 present various mechanisms of particle capture according to particle size and electric charges to model filtration efficiency of a fibrous filter.…”
Section: Filtration Theory In Fibrous Structuresmentioning
In air filtration, nonwoven materials are known to be pertinent structures for fine filtration and moderate pressure drop. In order to develop a filter that combines good permeability and high efficiency, it is important to identify the relevant structural parameters of the nonwoven. The main criteria studied in this paper are fiber fineness, solid volume fraction and basis length (total length of fiber in unit area of nonwoven). The effect of combining different fiber diameters in order to reach the best compromise is also investigated. Our results show that the use of binary blends of different fiber diameters improves overall filtration behavior, in comparison to nonwoven filters with equivalent unimodal diameter distribution. A theoretical filtration model is used to predict filtration behavior for different structural characteristics and these predictions are compared to experimental results. However, this comparison demonstrates the limits of existing models in the case of fiber blends.
“…Figure 3 shows filtration efficiency as a function of air permeability for all investigated samples: an inversely proportional relationship is found between these two properties, as expected. 25 It can also be observed that efficiency increases as fiber diameter decreases, which is also expected. Figure 3.Filtration efficiency E * versus air permeability* for unimodal fiber diameter (UFD) nonwovens.Figure 4.Filtration efficiency E * versus fiber basis length.Figure 5.Filtration efficiency E * versus solid volume fraction (SVF).…”
Section: Resultssupporting
confidence: 62%
“…Lee and Liu 24 and Davies 25 present various mechanisms of particle capture according to particle size and electric charges to model filtration efficiency of a fibrous filter.…”
Section: Filtration Theory In Fibrous Structuresmentioning
In air filtration, nonwoven materials are known to be pertinent structures for fine filtration and moderate pressure drop. In order to develop a filter that combines good permeability and high efficiency, it is important to identify the relevant structural parameters of the nonwoven. The main criteria studied in this paper are fiber fineness, solid volume fraction and basis length (total length of fiber in unit area of nonwoven). The effect of combining different fiber diameters in order to reach the best compromise is also investigated. Our results show that the use of binary blends of different fiber diameters improves overall filtration behavior, in comparison to nonwoven filters with equivalent unimodal diameter distribution. A theoretical filtration model is used to predict filtration behavior for different structural characteristics and these predictions are compared to experimental results. However, this comparison demonstrates the limits of existing models in the case of fiber blends.
“…As it can be seen from Figure 4 b, the increment in PM diameter dictates the capturing mechanism. At larger particle size (>1 μm), inertial impaction dominates over interception or Brownian motion, taking into consideration an assumption that the particles present in gas stream do not change its flow around the fiber, despite the fact that near fibers fluid streamlines deviate [ 47 , 48 , 49 , 50 ]. A particle with a diameter of ~2 μm, whose Stokes number St is > 0.5 (St = particle response time/characteristic time scale of flow), will mostly experience inertial impaction near a microfiber for a general flow velocity of ~10 cm/s.…”
Section: Filtration Of Pms Using Ultrafine Fibersmentioning
The ongoing global pandemic has bestowed high priority uponthe separation of air-borne particulate matters (PMs), aerosols, etc. using nonwoven fibrous materials, especially for face masks as a means of personal protection. Although spunbond or meltblown nonwoven materials are amongst the forerunners for polymer microfiber-based face mask or air filter development in mass scale, relatively new process of nonwoven manufacturing such as electrospinning is gaining a lot of momentum amongst the filter membrane manufacturers for its scalability of nanofiber-based filter membrane fabrication. There are several nanofiber-based face masks developing industries, which claim a very high efficiency in filtration of particulate matters (PM0.1–10) as well as other aerosols for their products. Polyvinylidene fluoride (PVDF), which is commonly known for its use of tactile sensors and energy harvesters, due to its piezoelectric property, is slowly gaining popularity among researchers and developers as an air filter material. Electrospun PVDF nanofibers can be as fine as 50 nm in mass scale, which allows the membrane to have large surface area compared to its volume, enhancing nanofiber–PM interaction. At the same time, the breathability index can be improved through these PVDF nanofiber membranes due to their architectural uniqueness that promotes slip flow around the fibers. The conductive nature of PVDF makes it advantageous as a promising electret filter allowing better capturing of ultrafine particles. This review aims to provide a comprehensive overview of such PVDF nanofiber-based filter membranes and their roles in air filtration, especially its application in filtrate of air-borne PMs.
“…The term green infrastructure is a new term, but it is not a new idea that began a hundred and fifty years ago through planning and preservation efforts through two concepts: -Link parks and open areas. Conservation and linkage of natural areas to biodiversity, [15] The importance of green infrastructure can be summarized, [16] -Sustainable management of land and water resources, including production (eg energy and food crops), pollution control, climate improvement, increased land cover porosity, -Biodiversity.…”
Section: Sustainable and Green Infrastructuresmentioning
The world is facing many environmental and economic problems resulting from rapid urbanization and over-exploitation of available resources as well as due to the dramatic increase of the population and corresponding increases in the number of cities. Technological and industrial development plays a big role in these problems. As a result, the term green technology became as a tool to solve these problems with an orientation towards sustainable development at all levels. , It seems to be very effective tool in modern urban planning which incorporates of all aspects of planning such as infrastructure and industry, energy, telecommunications, transportation and other vital areas in cities. These technologies are environment friendly inventions that often involve -energy efficiency, recycling, safety and health concerns, renewable resources, and more. Green technologies include several forms of technology that help to minimize negative effects on the environment and create new ways to achieve sustainable development. This paper is about green technology and its role in sustainable urban planning, it aims to clarify the most important areas for the application of this technology and the benefits provided by these technologies in improving the lives of the population in cities and a development orientation towards sustainability.
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