Browse Publications Technical Papers 2003-01-1001
2003-03-03

Transient Emissions of a SULEV Catalytic Converter System Dynamic Simulation vs. Dynamometer Measurements 2003-01-1001

Simulation of catalytic exhaust gas aftertreatment systems is a cost and time saving method in the early development design stage to meet current and upcoming emission standards. Three-way catalytic (TWC) converter systems which target for 99% HC and NOx conversion need to be optimized for catalyst light-off as well as high conversion efficiency in the hot phase of the driving cycles.
A mathematical model of the three-way catalytic converter which contains all phenomena relevant for the simulation of the transient emission performance is described. Special attention is given to oxygen storage and release since a proper description of this mechanism turns out to be crucial. The 1D simulation model balances the enthalpy in the gas and in the solid phase, the species H2, CO, C3H6, C3H8, O2 and NO in the gas bulk phase and close to the catalytic surface. Furthermore, the oxidation extent of the oxygen storage is accounted for. An adaptive method based on spatial and temporal error control is applied to solve the resulting system of highly non-linear partial differential equations (PDEX).
The process of gaining oxygen storage capacities (OSC) and kinetic data for oxygen storage/release kinetics in isothermal slice reactors is outlined.
The two-brick underfloor system of Volkswagens Super-ULEV emission concept in a 2.0L-2V SI engine has been chosen for verification and validation of the simulation tool. Emission and temperature profiles have been measured during an FTP75 driving cycle on a dynamometer, especially to validate the model and its independently determined parameters.

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