Internal and External Measures for Catalyst Light-Off Support 2015-24-2501
Within a project of the Research Association for Combustion Engines e.V., different measures for rising the temperature of exhaust gas aftertreatment components of both a passenger car and an industrial/commercial vehicle engine were investigated on a test bench as well as in simulation. With the passenger car diesel engine and different catalyst configurations, the potential of internal and external heating measures was evaluated. The configuration consisting of a NOx storage catalyst (NSC) and a diesel particulate filter (DPF) illustrates the potential of an electrically heated NSC. The exhaust aftertreatment system consisting of a diesel oxidation catalyst (DOC) and a DPF shows in simulation how variable valve timing in combination with electric heated DOC can be used to increase the exhaust gas temperature and thus fulfill the EU6 emission limits.
The measurements of the industrial/commercial vehicle engine showed that the use of heating measures allows for operating such an engine for off-road applications. Even in a transient cycle, a compliance with the limits of the EUVI emission standard could be achieved. Simulative optimizations reduced fuel consumption for all configurations and engine variants without exceeding EU6/EUVI limits, though they were still too high. However, with low temperature activity of the aftertreatment components, and a better isolation of the exhaust system or a reduction of the engine raw emission level, there is still potential to further reduce fuel consumption.
Therefore, heating measures investigated in this paper were not only evaluated regarding EU6 emission standards, but also with respect to their CO2 emissions. For this purpose the simulation tool AbSim was developed.