Flow Field and Pressure Drop of Filters with Rectangular Fibers

ABSTRACT. The viscous flow fields around multifiber filters have been investigated in a previous paper. The results of the previous work show that the flow becomes periodic immediately after the first fiber array downstream from the entrance if the fibers are arranged uniformly along the flow direction. The characteristics of such flow fields enable the pressure drop and the particle interception efficiency of a multifiber filter to be represented by single-fiber models. The total filtration efficiency, however, cannot be so represented since fibers interact during filtration processes. In this study, the pressure drop and the interception efficiency were investigated by making use of the viscous flow fields modeled in the previous research. The fiber separation ratio was found to have significant effects on pressure drop and efficiency.At a given volume fraction, changes in the fiber separation ratio will result in changes to the patterns of fluid flow and aerosol particle motion. Therefore, the fiber separation ratio significantly affects pressure drop and interception efficiency.

Section: Ap and Interception In Multifiber Filters 315mentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Pressure Drop and Interception Efficiency of Multifiber Filters

Liu

Wang

1997

“…The ow patterns obtained by the cell models have been shown to be the most accurate, as they consider the effect of neighboring bers and the results were numerically validated using two-dimensional modeling (Rao and Faghri 1988;Fardi and Liu 1992). However, the experimentally obtained pressure drops in real media are less than that predicted theoretically by Kuwabara's cell model.…”

Section: Introductionmentioning

confidence: 86%

An Asymmetrical, Three-Dimensional Model for Fibrous Filters

Dhaniyala¹

1999

ABSTRACT. The ow in a lter media represented by a three-dimensional ber arrangement has been modeled using a nite volume approach. This results in a better estimate of ber drag and accounts for some of the difference between theory and experimental results. In addition, the effect of inter ber distance and packing density distribution on drag characteristics is obtained numerically. An equivalent ber diameter based on the numerically obtained ber drag is compared with experimental values. The excellent agreement of numerical results with experimental values reveals the advantage of considering these media properties in modeling lter behavior. INTRODUCTIONThe important parameters in evaluating a lter media are pressure drop and particle collection ef ciency, and these parameters are dependent on the operating conditions and media properties such as ber size and packing density. Theoretical and numerical modeling of ow through the media is required to predict lter performance and enable design optimization. The lter media is represented by a simple structure, and the ow eld in this structure is used in calculating the lter characteristics. The accurate estimation of media performance requires an ideal representation of the real lter structure.The ow in a lter is generally in the low Reynolds number regime and follows Darcy's law (Davies 1973) with a linear dependence of pressure drop on face velocity. This is represented as:

“…Here, we quote the studies of Brown (1984), Fardi and Liu (1992a), Wang (1996), Ouyang and Liu (1998), and Dhaniyala (1999) for flow field and pressure drop, and Fardi and Liu (1992b) for capture efficiencies due to Brownian diffusion and interception, Zhu et al (2000) for capture efficiency due to inertial impaction, and Adamiak (1999), Cao et al (2004) and Cheung et al (2005) for the filtration performance in an electric field. Hosseini and Tafreshi (2011) investigated the effects of fibers' cross-sectional shape on the performance of a nanofiber filter (in the slip flow regime) and a microfiber filter (in the no-slip flow regime).…”

Section: Introductionmentioning

confidence: 99%

Simulating and Modeling Particulate Removal Processes by Elliptical Fibers

Wang

Zheng

2013

A lattice Boltzmann-cellular automata (LB-CA) probabilistic model for two-phase flows was used to simulate the particle capture process of elliptical fiber. The pressure drop and capture efficiency due to various capture mechanisms (Brownian diffusion, interception, and inertial impaction) were investigated. It is found that the diffusional capture efficiency of the elliptical fiber is greater than that of the circular fiber because of its larger capture area, which is proportional to the aspect ratio. When the interception or inertial impaction is dominated, aspect ratio, orientation angle, and the ratio of particle diameter to the fiber diameter affect the capture efficiency of the elliptical fiber, which is usually higher than that of the circular fiber except that the major axis is parallel to the incoming flow. The correction factors for the pressure drop and capture efficiency of elliptical fiber from those of circular fiber were attained through the Levenberg-Marquardt algorithm, which is used to fit some well-organized LB-CA simulations. These empirical correction factors can combine the classical models for circular fiber to calculate the pressure drop and capture efficiency for elliptical fiber in a simple way. Finally, the quality factors of elliptical fibers as a function of the aspect ratio and orientation angle were investigated, which is conducive to optimization configuration of elliptical fiber in different operation conditions.