Effect of Nano-Filtered Intake Air on Diesel Particulate Matter Emissions

While most reductions in diesel particulate matter (PM) have been implemented through internal engine improvements and aftertreatment systems, additional reductions may be found by controlling intake contaminants. Under the ideal conditions of operating with ultra low sulfur diesel fuel and filtered and conditioned intake air, a diesel engine produces a certain amount of PM. The PM emission levels may increase when intake air is polluted during harsh on- or off-road conditions. In this study, contaminants were allowed to enter the intake tract of the engine to determine whether or not increased particle ingestion leads to increased particulate matter expulsion. Diesel and test dust contaminants dispersed in intake air were filtered using both a conventional filtering medium and a nano-medium to determine their effects on diesel engine-out PM emissions.

The paper characterizes the two media by microstructure, permeability, porosity, and fractional efficiency. Exhaust gas particle size distributions show reduced number concentrations for the nano-material versus the stock material during steady-state modes, which was consistent with predictions. Gravimetric tests during transient cycles also showed improved results for the nano-material. During transient cycles, diesel-contaminated intake air led to higher total PM mass emissions, while test dust-contaminated intake air showed lower total PM mass emissions, compared to non-contaminated intake air.