Impacts of Diesel-HEVs on exhaust gas aftertreatment systems for future emission legislations

Abstract

The ongoing electrification of Diesel powertrains along with the introduction of new test procedures by the European Union creates new challenges for the development of the next generation of exhaust gas aftertreatment systems. The electrification leads to changed operating conditions of the combustion engine resulting in temporarily higher engine-out emissions and simultaneously lowered exhaust gas temperatures. Additionally, the exhaust gas aftertreatment system will have to deal with higher exhaust gas mass flows, due to the upcoming new test procedures and real driving emission tests. Therefore the boundary conditions at Diesel-HEVs require a close coupled positioning especially of the DeNOx function to ensure high conversion rates over wide range of operating conditions and engine out emissions. The DeNOx potential of different exhaust gas aftertreatment systems for the use in Diesel-HEVs will be discussed in this paper. On the one hand, the applied testing methodology includes tests at the Engine-in-the- Loop (EiL) testbed. With the EiL testbed the simulation of different powertrain configurations is used to show the influence of these configurations on the thermal conditions in the exhaust gas aftertreatment system and to evaluate the emissions and their conversion. On the other hand, on road and vehicle dynamometer measurements with state of the art Diesel-HEVs are used to determine the NOx emissions and thermal conditions during real driving scenarios.