Model-based comparative study of Euro 6 diesel aftertreatment concepts, focusing on fuel consumption

Abstract

A model-based study is used to assess various Euro 6 diesel PM/NO x aftertreatment concepts for one specific engine and vehicle combination. The assessment focuses on fuel consumption/carbon dioxide (CO2) emissions considering the fuel penalties resulting from both a periodically regenerating system as well as a catalyst heat-up strategy. The modelling work is carried out with a complete platform for simulating transient thermal and chemical phenomena of all exhaust aftertreatment components. It is shown that, in all cases, the selective catalytic reduction (SCR) system requires a heat-up strategy to satisfy Euro 6 NO x emissions limits, making configurations with an SCR located upstream of the particulate filter more favourable. On the other hand, it is verified that these configurations suffer owing to the lack of passive regeneration that, in turn, increases the active regeneration frequency. The use of a catalyzed particulate filter upstream of the SCR allows for an increase in NO x conversion efficiency. The use of an heat-up strategy for SCR light-off promotes the passive regeneration effect. The benefit of using a fuel-borne catalyst (FBC) system for active regeneration is confirmed. Finally, all these aspects are quantified and the overall fuel penalty results are presented and discussed.