A structure-based penetration model for the mechanistic interpretation of filtration regimes in baghouse needle-felt filter media

This study introduces a physically motivated, structure-based modelling framework for interpreting the penetration behavior of cleanable needle-felt media used in baghouse filtration. Derived from classical fibrous filtration theory, the model expresses penetration in terms of the specific fiber surface area ( 𝑺 ), a structural descriptor calculated directly from readily available media properties such as grammage and fiber fineness (dtex). It applies to the state of maximum penetration, or minimum collection efficiency, represented by new media and by regenerated media before significant filter-cake re-formation. Penetration data for polyester needle felts from two industrial media families, examined in both new and aged states, were well described by the predicted exponential dependence 𝑃 = 𝑃 0 ⁢ e x p ⁡ ( − 𝑘 𝑺 ) wherein a single structural coordinate ( 𝑺 ) can systematically organize the experimental data and relate penetration behavior to media structure within each media family. The resulting regression parameters reflect systematic differences in filter behavior with mechanistic significance. The slope parameter ( 𝑘 ) is interpreted as an effective accessibility or utilization factor for the internal fiber surface of the upstream layer, whereas the offset term ( 𝑃 0 ) represents additional capture mechanisms not directly described by nominal fiber surface area, such as preferential particle capture near the outer filter surface as expected in strongly calendered or membrane-like structures, or capture in deeper regions of the needle felt. The results show that the specific fiber surface area 𝑺 , derived from conventional manufacturer data, can provide a practical framework for interpreting the penetration behavior of industrial needle-felt media. Although broader validation across additional media types and operating conditions remains clearly necessary, the framework provides a practical basis for mechanistic analysis of their emission behavior in relation to media structure.