A Model Approach to Simulate Exhaust Gas Temperatures of Diesel Oxidation Catalysts

Various exhaust gas aftertreatment systems are used in the internal combustion engine to comply with the current exhaust gas standards. The diesel oxidation catalyst (DOC) is used in the diesel engine to oxidize carbon monoxide and hydrocarbons outside the engine. In order to ensure optimal operation and thus a high conversion rate, the light-off temperature must be reached at all times. The temperature modelling of the exhaust gas temperature after the catalytic converter represents a high degree of complexity due to the chemical energy release in the catalytic converter. In the model presented here, the chemical energy release is calculated on the basis of the reaction enthalpies of a one-step chemistry. In addition, the agglomeration of the hydrocarbons in the catalyst and their rapid burn-off when the light-off temperature is reached are taken into account. By combining both processes, an accurate modelling of the exhaust gas temperature in the catalyst is possible, which additionally takes into account strong temperature increases due to rapid conversion of stored hydrocarbons.