Model based exhaust gas estimation of a common rail diesel engine

In order to improve fuel economy and the emissions of internal combustion engines, it is necessary to model the combustion process as a basis for control. In this paper, behavioral models are adopted as a compromise between accuracy of description and model complexity. The fuel injection and vaporization process is resolved into three zones: fluid droplets, vaporized and combusted fuel. The combustion chamber is divided into areas of burned and unburned gases, separated by the flame front. The chemical model for calculating emissions is based on the two-zone model. The amount of mass, which is transferred from the unburned to the burned zone, is the input for a chemical model based on the equilibrium for the OCH-system (oxygen/carbon/hydrogen), The result is the total quantity of masses in the burned zone. The nitrogen-oxide emissions are calculated by using the advanced Zeldovich-mechanism which uses the reaction-kinetic approach rather than the less accurate chemical equilibrium assumption. The NOx-Emissions (nitrogen-oxides) can be influenced by changing the exhaust-gas recirculation (EGR) rate. Copyright (C) 2001 IFAC.