Validation of a new phenomenological 'jump-and-channel' model for the wet pressure drop of oil mist filters

摘要

The "wet pressure drop" of oil mist filters (i.e. the increase in differential pressure of the air flow due to loading of the filter with liquid) is presented as a function of two mechanisms by which coalesced oil is transported through the filter. These mechanisms operate in separate regions of the filter and make separate (and separately measurable) contributions to the overall wet pressure drop. This new concept, which was first formulated qualitatively in a phenomenological model by Ramps et at (2(114), leads to semi quantitative predictions regarding the dependence of pressure drop Lip and saturation S on filter operating conditions, filter properties and liquid properties. These predictions arc first formulated and then validated for a range of wettable and non wettable filter media in combination with 4 mineral oils of different viscosity. The key findings, summarized below, are consistent with the model and apply to both wettable and non wettable media.