Combination of methods for characterization diesel engine exhaust particulate emissions

This paper describes a study of the exhaust aerosols produced by a diesel engine. A combination of techniques for collecting and measure particulate matter in a diluted exhaust gases are presented. Three techniques have been used: a Micro Orifice Uniform Deposit Impactor (MOUDI), a Low Pressure Impactor (LPI) and a Scanning Mobility Particle Sizer (SMPS). A direct injection naturally aspirated diesel engine was used in the study at three different equivalance ratios: 0.3, 0.45, and 0.6 at an engine speed of 1 400 rpm which is rated torque speed. Mass concentration measurements made with the MOUDI were in qualitative, but not quantitative, agreement with those calculated from the aerosol volume concentrations measured by the SMPS. The particulate matter obtained from the LPI was analyzed using transmission electron microscope and was found to be comprised of individual spherical particles ranging from 10 nm to 50,nm with a mean size of approximately 25 nm. Some conclusions about the size distribution measurement possibilities can be drawn.