Soot concentration and particle size in a DI CR Diesel engine by broadband scattering and extinction measurements

Actual emission legislation limits strongly the amount of pollutant in the atmosphere from internal combustion engine. In particular diesel engines widely emit NOx and particulate matter (PM). The last one has principally a carbonaceous nature and presents micronic and submicronic particles extremely dangerous for human health since it could deposit in the lung. In this work, a technique based on broadband ultraviolet (UV) visible scattering and extinction is applied inside a transparent DI CR diesel engine in order to analyze the soot evolution and oxidation. The study is carried out with particular detail for different injection strategies characterized of two and three injections per cycle, Pre+Main and Pre+Main+Post, considering the late combustion before the exhaust stroke. The analysis is performed in terms of size, mass concentration, and chemical and physical nature. The UV-Visible spectral range is chosen considering that the main pollutant precursors like aromatic compounds and carbonaceous matter present strong absorption band in this range.