EXPERIMENTAL STUDIES ON THE INFLUENCE OF DIESEL ENGINE OPERATING PARAMETERS ON PROPERTIES OF EMITTED SOOT PARTICLES

Physical and chemical properties of emitted soot particles are influenced by diesel engine operating parameters. In order to find correlations between the in-cylinder processes of combustion and the engine-out properties of soot particles, parameter studies were carried out on a modern light duty production diesel engine (turbo direct injection, TDI) and an optically accessed single cylinder diesel engine (single cylinder). Several techniques have been combined to analyze the combustion process as well as the emitted particles. The size of emitted soot particles of the TDI engine has been determined by a scanning mobility particle sizer (SMPS), and soot samples have been analyzed by a high-resolution transmission electron microscope (HR-TEM) and by thermogravimetry (TG). In addition, the internal combustion in an optically accessed single cylinder engine has been observed by time resolved spectroscopy as well as OH*- and C(2)-imaging. It turns out that in both cases, increasing injection pressure leads to a decreasing soot particle agglomerate and primary particle size with decreasing oxidation temperature.