Pressure Drop in Oil Mist Filter Media: Valadation of the Jump-and-Channel Model for a Broad Range of Air Velocities

Experiments were made with glass microfiber media of the type used in oil mist filtration to test the jump and channel model by Kampa et al. (2014) across a range of typical filter face velocities (5 cm/s to 70 cm/s). The data show that the wet Δp of an oleophilic filter is consistent with the model, in that the channel-Δp depends primarily on the loading rate, whereas a Δp jump for a given medium does not depend on the operating conditions. The data also show that the so-called steady state mode of filter operation (i.e. at constant velocity and loading rate) is actually quasi-steady at best, and that the “steady-state” Δp undergoes a gradual increase with time (termed “creep”) that depends on operating conditions. Experimental data are also presented for the internal oil distribution in the channel flow region and an empirical model expression is developed for the internal global saturation (i.e. the average saturation within the channel region). Different models are explored for the dependence of Δp on the internal oil distribution.