Reactivity of particles from gasoline engines: Relation to particle characteristics and engine parameters

• Applicants: Professor Dr. Thomas Koch; Professor Dr. Rainer Suntz; Professor Dr.-Ing. Dimosthenis Trimis
• Subject Area: Energy Process Engineering ; Hydraulic and Turbo Engines and Piston Engines
• Term: from 2016 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 316493809

The reactivity of soot particles with respect to oxidation is a measure of the reaction rate of the oxidation with e.g. O2 or NO2. This parameter, which is essential for the regeneration of particle filters in diesel or gasoline engines (DPF or GPF), is currently a hardly predictable property of such particles due to the fact that influencing variables and reaction mechanisms are only incompletely known. Important influencing factors on the reactivity of soot particles in the temperature range relevant for the regeneration of particle filters were elucidated in a two-year research project preceding the requested research project.In this preparatory work, the dominant property for the reactivity was the extension of the graphene layers within the primary particles. Furthermore, by comparing soot particles from a GDI engine with those from a model burner and modifying the reactivity through the engine operating conditions or the synthesis conditions, it could be shown that engine soot particles can be mapped with regard to the reactivity towards oxidation by particles from model burners. Finally, it was shown that infor-mation about the reactivity of soot particles during the formation and post-oxidation can be obtained by laser-optical in-situ methods. With the laser-optical methods, an in-situ characterization of the reactivity of soot particles is possible.The main aim of the research project proposed here is to further elucidate the influence of engine operating parameters on the reactivity of soot particles from direct-injection gasoline engines. The project builds on the basic knowledge about the property-reactivity relationships gained in the previous work, which will be detailed in the further course of the project. In particular, questions that have not yet been dealt with, such as the role of aromatic and oxygen-containing fuel components, are to be investigated and the knowledge gained is to be incorporated into physicochemical-based models for use in GPFs. Furthermore, kinetic approaches for the oxidation of the soot particles are to be developed from the experiments, which are used in combustion models for GPF particle filters. Likewise, the comparability of particles from the DI gasoline engine under different operating conditions with particles from the model burner systems should be deepened with regard to properties that go beyond the nanostructure. An important sub-goal is to track the nano-structural properties of the soot particles, which were identified for their reactivity in the preliminary work, in-situ in the engine and in the exhaust system by optical methods. This makes it possible to program the reactivity of the soot particles with the aid of motor parameters and the burning behavior of the particles on the soot filters.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr.-Ing. Henning Bockhorn; Dr.-Ing. Heiko Kubach; Dr.-Ing. Alexandra Loukou