Particulate Emission from Internal Combustion Engines

In this work, number concentration and size distribution at the exhaust of a Port Fuel Injection (PFI) Spark Ignition (SI) engine downstream a three-way catalyst and a Direct Injection Common Rail Diesel engine have been measured with two particle size instruments. The gas exhaust is first diluted, a nano DMA is used to obtain the particles size distribution function in the 3-60 nm range, in parallel, an electrical low pressure impactor (ELPI) is used to investigate a wider size range of 7 nm up to 10 μm. The two sizing techniques furnishes complementary information, in particular, DMA resolution is necessary to obtain the true distribution of the smaller particles. The measurements show that the Spark Ignition engine emit a large number of particles in all the investigated conditions. The maximum of the particles size distribution is measured at about 4nm. At the exhausts of a Diesel engine small particles are less abundant and difficult to detect.