On the filtration performance of dust-loaded trilobal fibers

Abstract

This paper is prepared to shed some light on the filtration performance of fibers with trilobal cross-section in comparison to their circular counterparts when loaded with aerosol particles. A trilobal geometry consisting of three overlapping elliptical lobes with major and minor diameters of 8 and 4μm, and a particle diameter range of 0.125–2μm are considered as representative examples of fibers and particles of a common aerosol filtration application. The results reported in this paper are obtained using micro- and macroscale simulation methods that we previously developed for modeling unsteady-state dust-cake formation inside and outside fibrous filters. Different flow velocities are considered to discuss performance of trilobal fibers under different particle capture regimes. For the range of particle and fiber diameters considered, the trilobal fibers are found to outperform their circular counterparts only when the particles are highly inertial, and only if the orientation of the trilobal cross-section with respect to the incoming flow is such that one of the grooves of the fiber faces the flow with a normal angle. This is in agreement with our previous simulations of clean trilobal fibers. In the case of low inertial particles, trilobal fibers were found to exhibit a higher efficiency with loading but at the expense of a significantly higher pressure drop. With the lack of perfect control over how the grooves will be oriented in a fibrous filter, one may conjecture that, other parameters being constant, the probability of an aerosol filter comprised of trilobal fibers performing better than its counterpart made of circular fibers is not very high. We also studied the effects of the through-plane orientation of the trilobal fibers on their performance relative to their circular counterpart. Similar conclusions were drawn from the latter simulations.