Theoretical modeling of filtration by nonuniform fibrous filters

Modeling commercial filter media using classical theories results in incorrect filter pressure drop and efficiencies and this is attributed to media inhomogeneity. The use of an arbitrary inhomogeneity factor is seen to be inadequate in accounting for the effect of operating conditions on the performance of inhomogeneous filter media. A simplistic theoretical modeling approach is described here to account for the variations in filter packing densities and to estimate their effect on the media particle capture characteristics. The theoretical modeling results are used in obtaining an equivalent filter packing density distribution from media local efficiency measurements. Considering this variation in the theoretical models is seen to result in better prediction of media performance over a wide range of operating conditions. The observed deviation of experimental efficiencies from the theory at smaller Peclet numbers can be explained from the results of the theoretical analysis.