Present Status of Air Filters and Exploration of Their New Applications

Abstract

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 enhanced interception effect. 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 nanofiber filtration. In the present review, the present status of development of high performance air filters are reviewed. We may use air filters not only for the removal of particles but also for the classification of particles by selecting an appropriate filter by operating it under an optimized filtration condition for classification. Other topics introduced in the present review are the applications of filters and metal screen for aerosol classification and the use of centrifugal force for enhancing collection efficiency without increasing the pressure drop.

Performance factors for filtration of air using cellulosic fiber-based media: A review

“…Such densification will tend to decrease the sizes of pores within the material, and some pores may become closed. In addition, a tendency of the fibrous material to form clumps will decrease the effective surface area, leading to a loss of filtration efficiency (Lee et al 2020).…”

Effect of surface charge density on electret filters charge degradation by organic solvent exposure

“…Many researchers have used the theoretical methodology to determine the surface charge density of a meltblown electret filter, where the net surface charge of the filter is almost zero [31,32]. In filtration theory, uncharged ultrafine particles are captured in an uncharged filter by diffusion and interception capture mechanisms [33][34][35][36]. However, the additional dielectrophoretic capture mechanism is dominant when uncharged ultrafine particles pass through a charged filter [36,37].…”