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

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 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.

Present Status of Air Filters and Exploration of Their New Applications

“…Many researchers made efforts to fabricate air filters with low air resistance and high collection efficiency (Hung et al, 2011;Sambaer et al, 2011;Mei et al, 2012;Uppal et al, 2013;Cho et al, 2013;Hassan et al, 2013;Choi et al, 2014;Balgis et al, 2015;Wang et al, 2016;Zhang et al, 2016;Zhao et al, 2017;Choi et al, 2017). Most studies to fabricate nanofibers used an electrospinning process, which has a limitation of a low production rate.…”

“…As for the first topic, nanofiber filters have attracted great attention because of the development of various manufacturing techniques of nanofibers (Choi et al, 2014;Choi et al, 2017;Xia et al, 2018). First part of this review will focus on the first topic.…”

Investigating the wicking behavior of micro/nanofibrous core‐sheath PET–PAN yarn modified by dimethyl 5‐sodium sulfoisophthalate

“…3 Therefore, one alternative approach is the combination of nanostructure and microstructure within a single structure that has been reported in many research studies. 4 Such structures have the benefits of both components and in some cases exhibit properties which are scarcely found in either component alone. The structural integrity and sufficient abrasion resistance can be achieved by yarn twisting.…”

Starch-based and multi-purpose nanofibrous membrane for high efficiency nanofiltration

“…In recent years, active components for ltration have stemmed from membranes, 6 lter papers 7 and microbers. 8 However, each type of component was inherited with different kind of drawbacks. Flexible and cost-effective, lter papers have low ltration efficiency as their inner structures were made of micron-sized cellulose short and long bres.…”

“…9 Despite their natural bending strength, lters made of synthetic microbers also suffered low ltration efficiency due mainly to their micron-sized internal porous structures. 8 Costly, several porous membranes lack required exural strength for the nal products to be pleated into various kinds of lters. 10 As efforts have been made to overcome such multiple weaknesses associated with existing lter systems, nanobrous membranes have emerged as one of the most promising alternative to high efficiency ltration.…”