Fractional Efficiency and Particle Mass Loading Characteristics of Engine Air Filters

The performance of the air cleaning filter is important to the long-term performance and reliability of the engine and its components. In this study, the performances of cellulosic and foam filter media for engine air cleaning application are experimentally investigated. Phenolic and non-phenolic cellulose filters were studied. Both flat-sheet and pleated cellulose filters were included. The foams filters were reticulated polyurethane foam media from 20 to 110 pores-per-inch. We measured the initial air flow resistance, the collection efficiency as a function of particle size, and the behavior of dust loading. We also studied the effect of oil treatment on filter performance. The results show that the efficiencies and pressure drops of the cellulose filters increase rapidly with dust loading. Oil treated cellulose filter was found to exhibit slower increases in pressure drop and collection efficiency, resulting in higher dust holding capacity. The foam filters showed good collection efficiency for particles larger than 1 μm diameter. The foam media have higher dust holding capacity than the cellulose filters. This is because the foam media has very open structure and cake filtration does not occur. Finally, the principles of designing multi-layered foam filter are discussed.