Characterization of pleated filter media using particle image velocimetry

Use of pleated filter media for removing particles is required in industrial and residential sectors encompassing many applications. Pressure drop is an important factor used to evaluate the performance of pleated filter media. Research has been focused on examining the effects of pleated filter properties and pleat geometries on pressure drop and filtration efficiency but air velocity distributions. In this study, a noninvasive particle image velocimetry (PIV) technique was used to characterize the velocity distributions downstream of pleated filters. A custom filter containing a singular rectangular pleat was constructed for comparison between a computational fluid dynamics (CFD) numerical model and experimentally obtained PIV results. Results indicated that the trend between PIV and CFD was similar in general. Special attention is needed when modeling porous media as some discrepancies were observed near the corners of the pleated filter where the filter medium is less permeable due to compression of the fibers. Subsequently, the PIV technique was used with commercial pleated filters to study the effects of pleat geometry on the downstream velocity distributions. Air velocity distributions were affected by both the pleat geometry and the pleat stabilizing technique, which is commonly applied to pleated filters to maintain pleat shape and gaps between pleats. Results suggest that in addition to pleated filter geometry such as shape, density, and height, the geometric effects of pleat lock or pleat stabilizing techniques, should be also considered for estimating flow effects more realistically.