Günter Hohenberg

Diesel Oxidation Catalyst Application Strategies with Special Emphasis on Odour Reduction

This paper deals with problems arising on the one hand from applying diesel oxidation catalyst for minimizing HC emission at low exhaust gas temperatures prevailing in the European city driving cycle and on the other hand in preventing sulfate formation in the oxygen catalyst at higher temperatures as they appear, e.g. in the ECE R49 13-mode certification cycle. The main parameters influencing the catalyst efficiency - exhaust gas temperature level, sulfur content in the fuel and catalyst specifications - are discussed and new solutions to fulfill the conflicting requirements are presented. 18 refs., 20 figs.

Development and Application of a Semi-Empirical NOx Model to Various HD Diesel Engines

The currently well known tools to simulate the formation of nitride oxides in the diesel engine combustion process, i.e., empirical, zero- and quasi-dimensional (= phenomenological), and computational fluid dynamic (CFD) models, are capable of simulating well measured engine configurations that produce qualitatively and quantitatively useful results. In cases of new applications, however, only the trends may be accurately predicted. This presentation describes the derivation of a semi-empirical simulation model that is based on the first law of thermodynamics and chemical kinetic reaction rate considerations. Single cylinder test engines were used to validate the simulation model for different combustion systems and fuel injection systems. Additional investigations of multi-cylinder engines from different commercial vehicle manufacturers revealed good results. An adaptation of the model coefficients has as yet not been required.

Calculation of the wall heat transfer during start-up of SI engines

The introduction of CO2-reduction technologies like the Start-Stop-System and the more stringent future emission limits require a detailed optimization of engine start-up. Thus the thermodynamic analysis of the processes is advantageous for combustion concept development as well as for the calibration of the ECU. In the following article by Bosch is shown how the transient wall heat fluxes can be calculated during engine start-up.