A statistical model for prediction of pressure drop and collection efficiency of poly-disperse non-woven fibrous filters

Majid Zia, University of Rhode Island

Abstract

A fundamental theoretical study of pressure drop and collection efficiency by poly-disperse non-woven fibrous filters is performed. The fibrous filter is modeled as a two dimensional random arrangement of circular cylinders. The fluid flow through the dilute arrangement is calculated under the low Reynolds number assumption. The biharmonic creeping flow equation is solved using the boundary element method. The new model developed is appropriately called the statistical model where the results obtained by various random arrangements are averaged to obtain the final results. This model facilitates the examination of the effects of fiber size and mixing ratios, in addition to the micro-inhomogeneity directly present within the model.^ The statistical model is capable of showing the trends in pressure drop and collection efficiency experimentally measured by many investigators. The model shows that the complicated three-dimensional network of fibers in poly-dispersed fibrous filters can be effectively modeled by a two dimensional random arrangement of fibers with an effective solidity of half the global solidity of the filter. The effect of fiber size and mixing ratios are shown to be minimal for low degrees of poly-dispersity. The model also shows how the pressure drop and collection efficiency of fibrous filters can be deduced from simple inline or staggered array arrangements used by many investigators. The pressure drop and collection efficiency predictions are in good agreement with experimental results.^ In addition to the statistical model, the pressure drop for a wide variety of staggered array arrangement is calculated. The arrangement of fibers includes two distinct fiber sizes. The inline arrangements associated with each fiber size are staggered with respect to each other. The slow flow past the arrangement which is governed by the biharmonic creeping flow equations was solved by a non-conventional numerical method described by Sangani and Acrivos. The pressure drop results show two distinct parameters influencing the results in addition to the solidity. One is the available surface area of fibers and the other is the gap distant between the fibers. For dilute mixtures, it is shown that the surface area effects is the dominate factor. Also, the average of various configurations is shown to be directly proportional to the available surface area. ^

Subject Area

Engineering, Chemical|Engineering, Civil|Engineering, Mechanical

Recommended Citation

Majid Zia, "A statistical model for prediction of pressure drop and collection efficiency of poly-disperse non-woven fibrous filters" (1993). Dissertations and Master's Theses (Campus Access). Paper AAI9405837.
http://digitalcommons.uri.edu/dissertations/AAI9405837

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