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This paper reports an investigation of the particle size distribution of different homogeneous Diesel combustion systems in comparison to conventional diffusion controlled combustion system. The influence of different operating parameters such as load or degree of homogeneity on the number of particles and the particle size distribution, determined with a Scanning Mobility Particle Sizer, is pointed out. The homogeneous combustion of Diesel fuel possesses a large potential concerning NOX, soot and particle mass, but still a high number of nanoparticles is discharged. Additional experiments are reported, which were carried out to understand the high emission of nanoparticles at low soot combustion better and to determine the chemical composition of the nanoparticles.

Detailed investigations on wall film behavior in port injected SI engines show that a standard UEGO sensor leads to inaccurate results during transients concerning the real air/fuel ratio. Purpose of this paper is to identify the reasons for this behavior and developing a compensation strategy. Fuelling transients due to steps in the injection period at constant engine speed and MAP with modified sensors were carried out and the influence of the protective tube and the dynamic behavior of the measuring cell were found to be the essential parameters. The standard UEGO sensor can be used to determine the air/fuel ratio during transients, if the reasons for inaccurate results presented in this paper are considered.

Intensive research and development activities which have been carried out by automotive manufacturers and suppliers of the automotive industry are currently focused on new solutions to meet the strict exhaust gas emission standards defined by LEV, ULEV and EG III. While both CO and HC emissions have been curtailed further and require novel emission technologies, the latter takes on a higher priority due to drastic reduction imposed by ULEV regulations. In current emission control systems with three-way catalysts, the major part of these emissions is created during cold start and warm-up phases when the catalyst temperature is below its light-off temperature. The present paper reports on burner/catalyst systems for improving the catalyst's cold start performance, which is a novel technology compared to other known technologies such as electrically heated catalysts (EHC) and adsorbers.