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While metal fiber filters have successfully shown a high degree of particle retention functionality for various sizes of diesel engines with a low pressure drop and a relatively high filtration efficiency, little is known about the effects of lubricant-derived ash on the fiber filter systems. Sintered metal fiber filters (SMF-DPF), when used downstream from a diesel engine, effectively trap and oxidize diesel particulate matter via an electrically heated regeneration process where a specific voltage and current are applied to the sintered alloy fibers. In this manner the filter media essentially acts as a resistive heater to generate temperatures high enough to oxidize the carbonaceous particulate matter, which is typically in excess of 600°C.

This paper describes the study and the results obtained to determine the performance deterioration of diesel particulate traps due to ash accumulation. Based on the ash emission rate in an engine exhaust and the full-size trap volume, a flow and distance simulation technique was developed to translate the results from bench tests of small scaled down traps to engine conditions. Fuel doped with metalloorganic additives was used to accelerate the ash loading of the scaled traps. The study was conducted on both a cellular ceramic trap and a wire-mesh trap. Results indicate that for a 60 liter, ceramic trap mounted on the exhaust of a heavy duty engine, the pressure drop, Δp, will double in approximately 90,000 km. It is also seen that for the same size wire-mesh trap, the Δp will increase by 70% of the clean trap Δp in about 200,000 km. The paper also describes the work done to determine the effect of particulate trap pore size on ash accumulation in cellular ceramic traps.