Novel quasi-static method to simulate collection efficiency and pressure drop of coalescing filters

Abstract

Coalescence filtration is the removal of dispersed droplets from a gas or from an immiscible liquid using a fibrous filter. Coalescing media are designed to capture the droplets, allow them to coalesce with one another and grow, and let them drain from the filter under gravity. Conducting numerical simulation to predict the pressure drop and collection efficiency of a coalescing filter is a computational challenge. The current paper presents a novel approach to simplify this highly transient multi-phase problem and to thereby propose a practical and expedited approach to design such filtration media. This was achieved by first developing a MATLAB code to perform Pore Morphology Method (PMM) simulations of fluid saturation in the filter and then by using the resulting 3-D saturation profiles in ANSYS (enhanced with a series of in-house subroutines) to conduct aerosol filtration simulations. Our simulations, interestingly, revealed that collection efficiency of a coalescing filter can decrease with increasing fluid saturation in the media, while its pressure drop can only increase. Our simulation results are analyzed in detail and are discussed in the context of prior studies reported in the literature.