Simulation of pressure drop and capacity for pleated air filters loaded with dust

Air intake filters for combustion engines are commonly pleated and made of thin filter paper. At high dust concentrations these media function as surface filters. The properties of the dust cake and its distribution within the pleat then become crucial to pressure drop evolution and filter lifetime. The dust distribution in turn depends on the flow field in the pleat and particle properties. In this paper the Navier-Stokes equations are solved numerically for a domain representing one model pleat and then calculate particle trajectories and local growth rates of the dust cake. Continuous cake growth is approximated by assuming stationary flow during the deposition of an incremental amount of dust. Using such an approach the influence of pleat geometry, particle inertia and volume flow is investigated. Additionally, simple analytical models for the loading of idealized pleats are presented. U- and V- shaped pleats exhibit distinctly different loading behaviour. The pressure drop slope of U-shaped pleats is initially linear. V-shaped pleats show a non-linear rise of the pressure drop. Therefore, rectangular pleats will generally yield higher dust capacities than tapered pleats. ... mehrParticle inertia can have a pronounced effect on the loading curve of U-shaped pleats, while it is less important for V-shaped pleats. It is shown how dust capacity varies with pleat width. An optimum width exists because decreasing pleat width increases filtration surface while it diminishes the volume available for dust deposition. The results of numerical simulation and analytical model agree almost perfectly for the V-shaped pleat, and match qualitatively for the U-shaped pleat.