Aufklärung des Einflusses von C7 und C8 Aromaten auf die Partikelbildung im Abgas von Ottomotoren mit Direkteinspritzung sowie Entwicklung eines Screeningverfahrens zur Vorhersage der Partikelbildung

With the introduction of direct injection, particle emissions are the main focus of chemical and technical interest. The aim is to contribute to clarifying the influence of specific substance groups and individual components in gasoline on particle formation and, in particular, to identify the influence of C7 and C8 aromatics. The fuels are tested in stationary and dynamic tests on engine and chassis dynamometers. Particle number emissions are recorded using a condensation particle counter. In contrast to larger, more resonance-stabilized aromatics, toluene and xylene exhibited altered reaction behavior. Literature reviews and own considerations suggested that the benzy radical formed from C7 and C8 aromatics tends to form a five- or seven-membered ring under high pressure. Therefore it cannot contribute to PAH and soot formation. Soot reduction via five-ring formation is based on entropy-driven ring opening under high pressure. PAH precursors formed as a result do not significantly influence soot formation due to the short combustion time available. Theoretical considerations regarding the chemistry of the seven-membered ring formed from toluene show that the radical-carrying carbon atom of the tropyl radical would first have to undergo rehybridization from a sp2 to a sp3 hybridized carbon atom in order to be incorporated into the soot structure. Another focus of the work was the prediction of particle formation. For this purpose, particle formation prediction using the soot lamp and the modified Yield Sooting Index (YSI) as a screening method were compared in the laboratory. The prediction based on the YSI proved to be more accurate than that based on the soot lamp, while also requiring less time and material. However, the motor-based findings regarding the low contribution of C7- and C8-aromatic-rich fuels could not be reproduced either by experimental predictions using the soot point lamp or by calculating the YSI. This confirmed the thermodynamic dependence of the altered reaction behavior of low-boiling aromatics.

Author dc:creator

• Klose, Johanna

Advisors dc:contributor.advisor

• Brauer, Maximilian
• Garbe, Thomas

Licence dc:rights.uri

• https://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

de

Identifier URI

https://doi.org/10.14279/depositonce-25361

OAI identifier oai:identifier

oai:depositonce.tu-berlin.de:11303/26532