One essential focus of the European legislation for emission control is on the emission of particulate matter from direct injection (DI) gasoline engines. The reason is the difference in mixture formation compared to port fuel injection. Fine and ultra-fine particles may penetrate into the lung and cause damage of the different types of lung tissue. Therefore, the reduction of emission of particulates from DI gasoline engines is a task of highest priority.
Currently the development of DI gasoline engines favors exhaust gas treatment by particle filters to reduce the emission of particulates. The reduction of technical effort in exhaust gas treatment is another important task in engine development. In the reduction of the technical effort for aftertreatment the reactivity of particulates plays a dominant role. The reactivity of particulates is affected by the operating conditions of the engine. By knowing property-reactivity relations, the oxidation of particulates within the filter can be enhanced and controlled via the operating conditions of the engine.
The main objective of the present research project is the control of the reactivity of the emitted particulates by operation conditions of the engine and the enhancement of the reactivity through the optimization of these parameters. For this purpose property-reactivity relations will be developed, which form the scientific basis for the optimization of the burn-out of particulates in GPFs. A second objective is to mimic the properties of particulates affecting their reactivity by synthetic soot particles generated in model flames. This enables the investigation of the reactivity of particulates without highly costly test runs with engines. A third objective is measuring of the properties, that control the reactivity of soot particles insitu and on-line in model flames and DI gasoline engines.
To achieve these goals particulates are generated in a research one-cylinder DI gasoline engine and investigated with respect to the properties that affect their reactivity. The reactivity and properties of these particles are compared with those from synthetic soot particles generated in a model flame. By doing this, property-reactivity-relations can be developed which allow controlling the reactivity of particulates through the operation conditions of the engine. In the present discussion about reactivity of soot particles the main hypotheses relate the reactivity with the order, extension and modification of graphene layers within the primary particles and the surface properties of the particles. Therefore, these properties of the soot particles will be measured in-situ and on-line in model flames and in a second research engine with optical access by optical methods. Altogether, the research project will establish property-reactivity-relations for particulates from DI gasoline engines and by that the possibility to control particulate emission via engine operating conditions.