Modeling of the Transitional Pressure Drop of Fibrous Filter Media Loaded with Oil-coated Particles

Ta-Chih Hsiao,Da-Ren Chen

doi:10.4209/aaqr.2019.01.0002

Ta-Chih Hsiao, Da-Ren Chen

Open Access

https://doi.org/10.4209/aaqr.2019.01.0002

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Abstract

ABSTRACT The pressure drop of glass-fiber and cellulose filter media loaded with oil-coated particles was investigated. The focus of this study was to develop a model describing the pressure drop of fibrous filter media under the above particle loading condition. A set of experimental data collected during previous work was used for this modelling. For the cases where the coated particles possessed an oil volumetric percentage below 50%, the filter was divided into two layers: One layer collected all test particles while the other layer remained clean, and the pressure drop of the first layer was estimated using a modified Bergman model, whereas that of the second was calculated with the Davies equation. The total filter pressure drop is the summation of the layers’ pressure drops. For the cases where the coated particles possessed an oil volumetric percentage above 50%, a power-law equation with two parameters (viz., the exponent, n, and the critical volume, Vcr) was applied to fit the experimental data. The correlations of the above parameters with the solid-core diameter fraction (X) of the particles and the viscosity of the coating oil were calculated for the glass-fiber and cellulose filter media.

Highlights

Filtration of aerosol particles is a dynamic process (Bao et al, 2015; Choi et al, 2017; Sachinidou et al, 2017)
For the cases where the coated particles possessed an oil volumetric percentage below 50%, the filter was divided into two layers: One layer collected all test particles while the other layer remained clean, and the pressure drop of the first layer was estimated using a modified Bergman model, whereas that of the second was calculated with the Davies equation
When the liquid volumetric percentage is less than 50%, the pressure drops of glass-fiber filters and cellulose filters are primarily caused by the solid fraction of the loaded oil-coated particles

Summary

INTRODUCTION

Filtration of aerosol particles is a dynamic process (Bao et al, 2015; Choi et al, 2017; Sachinidou et al, 2017). The drag coefficient of dust-loaded fibers per unit filtration area (Cdm) and the diameter of a dust-loaded fiber (dfm) are two critical parameters in this model They were correlated with the filtration condition and collection mechanism along with the dimensionless accumulated particle volume, Vac, defined as the ratio of loaded particle mass to particle density and filter packing density per unit filter volume. Kanaoka and Hiragi (1990) further classified the rate of increase of dfm into three stages: no growth at low Vac, rapid growth at intermediate Vac, and dampened growth at high Vac. They were correlated with the filtration condition and collection mechanism along with the dimensionless accumulated particle volume, Vac, defined as the ratio of loaded particle mass to particle density and filter packing density per unit filter volume. The fiber diameter, df, and packing density, αf, are replaced with the “coated” fiber diameter, df,w, and new packing density (αf + αl), which includes the loaded droplets

64 UdZ l f l d

Findings

CONCLUSION