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ABSTRACT
This article is the second part of a two-part series. The first part, "Investigation of Particle Penetration in Fibrous Filters: Experimental, " appeared in the January/February, 1999, issue of the Journal of the lEST. The performance of seven state-of-the-art air cleaning filter media having a wide range of filter efficiencies is described. The figure of merit values have been obtained to compare the performance of different media. The experimentally obtained pressure drops and the theoretically calculated fiber drags are used in deriving an expression to calculate an equivalent fiber diameter for different media. The theoretical values of fiber diameter compare well with the experimental observations. Use of the equivalent fiber diameter values in calculating the parameters of the dimensionless correlation model results in better agreement between the experiments and theory. The calculated equivalent fiber diameter is useful in predicting the most penetrating particle size of different media.
Keywords: filtration, theoretical, figure of merit, equivalent fiber diameter, theoretical correlations, slip effect
This article is the second part of a two-part series. The first part, "Investigation of Particle Penetration in Fibrous Filters: Experimental," appeared in the January/February, 1999, issue of the Journal of the IEST. The important characteristics of a new filter media are pressure drop and particle collection efficiency. A semi-automated filter test system1 was used in evaluating the performance of several state-of-the-art commercial filters with a wide range of efficiencies. The relative performance of these media can be compared by obtaining the filter figure of merit values. The figure of merit is an important parameter that correlates pressure drop and filter efficiency2 at a particular velocity. This parameter can be used to compare and contrast media with differing properties.
A general correlation model based on the experimental behavior of media is useful in the design or modeling of fibrous filters. The correlation model can be used to predict media performance as a function of filter properties and operating conditions. There are several correlation models for fibrous filters.3-5 The use of these models requires a prior knowledge of the average filter properties, such as fiber diameter, packing density, and filter thickness. An average value of the media fiber diameter is the most critical and difficult to obtain experimentally.
The fiber diameters...