Impact of Injection Strategy on Soot Reactivity and Particle Properties of a GDI Engine 2020-01-0392
The gradual global tightening of emission legislation for particulate matter emissions requires the development of new gasoline engine exhaust aftertreatment systems. For this reason, the development of gasoline direct injection engines aims at the reduction of particulate emissions by application of Gasoline Particulate Filter (GPF). The regeneration temperature and behaviour of GPF depend on soot particle reactivity towards oxidation and therefore on the micro- and nanostructural particle characteristics. The investigations on particle emissions were carried out on a turbocharged 4-cylinder gasoline engine with direct injection that allows the variation of injection parameters. The emitted soot particles have been in-situ characterized towards their number and size distribution using an engine exhaust particle sizer (EEPS). Ex-situ analytics focuses on the analysis of oxidation kinetics and the nanostructural characteristics affecting soot reactivity significantly. In addition, soot reactivity regarding to oxidation relies significantly on the quality of mixture formation depending on injection strategy. These findings are in very good agreement with the nanostructural parameters obtained by high-resolution transmission electron microscopy (HRTEM). Particles formed in a relatively homogeneous air/fuel mixture show a reduced mean graphene layer length, which corresponds to higher oxidation rates. Conversely, inhomogeneous mixtures result in increased formation of large particles with long, extended graphene layers, which in turn lead to low reactivity.
Sergej Koch, Heiko Kubach, Amin Velji, Thomas Koch, Fabian P. Hagen, Henning Bockhorn, Alexandra Loukou, Dimosthenis Trimis, Rainer Suntz
Diploma Engineer, Karlsruhe Institute of Technology, Karlsruhe Institute Of Technology