Analytical expressions for predicting performance of aerosol filtration media made up of trilobal fibers

Despite the widespread use of fibrous filtration media made up of trilobal fibers (referred to as trilobal media here), no mathematical formulations have yet been developed to predict their collection efficiency or pressure drop. In this study, we model the cross-section of a trilobal fiber with three overlapping ellipses separated from one another by a 120° transformation. We generate 2-D models representing the internal structure of trilobal filters having fibers with different dimensions and aspect ratios, and used them to predict pressure drop and collection efficiency of trilobal filter media. This information is then utilized to define an equivalent medium with circular fibers for each trilobal filter. Our results indicate that the circumscribed circle of a trilobal fiber can serve as an equivalent circular diameter, and therefore be used in the existing empirical/semi-empirical correlations that have previously been developed for predicting performance of filters with circular fibers. We have also proposed easy-to-use expressions that can be used with our equivalent circumscribed diameters for calculating the pressure drop of trilobal media.