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Modelling of a Lean NOx-Trap system with NO/NO 2 differentiation and sulfur poisoning
Abstract:
One of the challenges in the automotive industry is to develop
new vehicles and new technologies with minimal costs. In this
context, modeling becomes an important tool for the design of
future technologies by reducing the number of tests needed to
develop a new exhaust system. With the emergence of future European
standards, which are more restrictive on NOx and takes account of
the differentiation between NO and NO₂ emissions, European
manufacturers have to describe precisely the formation and the
behavior of NO₂ in the aftertreatment systems.
The aim of this study is to improve the one-dimensional
aftertreatment models developed by Renault by introducing the NO₂
contribution from the engine to the tailpipe. The first part of
this study focuses on the adaptation of aftertreatment systems
models in order to differentiate NO and NO₂. Thus different global
kinetics models for the Lean NOx-Trap System were studied.
Different runs were carried out either at Renault or at the
"Laboratoire de Réactivité de Surface," for understanding
the phenomena involved in NO₂ formation and consumptions. Then, the
calibration of the model has been performed. Part of this paper
focuses on the choice of an automated optimization method for this
calibration step. By the end, the final model was validated versus
engine bench tests performed on full size monoliths. The second
part of the study describes more precisely the integration of the
sulfur poisoning effect in the Lean NOx-Trap Model including the
integration of NO₂ in the model.