To cite this version:Nikola Rankovic, Guillaume Bourhis, Mélanie Loos, Roland Dauphin. Knock management for dual fuel SI engines: RON evolution when mixing low RON base fuels with octane boosters. Fuel, Elsevier, 2015, 150, pp. AbstractMost of the time, Spark Ignition (SI) engine performance is limited by knock phenomena (especially for turbocharged engines), which are linked to fuel resistance to auto-ignition, quantified by its octane number (Research Octane Number -RON and Motor Octane Number -MON). If high octane numbers are crucial for efficient high load operating points, they are less necessary at low load. Thus, if the octane number of the fuel could be tuned as any other engine setting parameter, the engine efficiency and CO 2 emissions could be improved, leading to an "Octane on Demand" concept, using for instance a dual fuel strategy. This requires understanding the behavior of dual fuel combustions with lower / higher octane fuels, and more particularly the evolution of RON when blending high RON fuels with low RON ones.Developing an Octane on Demand concept requires to choose appropriate octane enhancers and understand their blending behavior. For this purpose, RON measurements were performed on a CFR engine using a wide range of mixtures of low-octane base fuels with various boosters capable of increasing the antiknock resistance of the blends. The chemical composition of booster streams was chosen to assess the potential of using alternative refinery products for improving fuel resistant autoignition properties when added to a whole-range naphtha and RON 91 gasoline. The study covers five octane boosters: ethanol, reformate, di-isobutylene, 2-butanol, and a mixture of butanols.The experimental results show a non-linear behavior of RON values with respect to volumetric incorporation rates of octane boosters. In the cases when the booster is an alcohol (C2 or C4), linear bymole blending rules can be applied with an acceptable prediction error. For boosters rich in olefins and aromatics, molar blending becomes less accurate. Ethanol shows the strongest boosting effect among all the octane boosters on the one hand, and on the other hand, the octane enhancing effect is stronger for the base fuel of lower starting RON value. Experimental results of the current study represent a comprehensive database for tailoring fuel RON properties aimed to explore combustion behavior of lowoctane fuels enhanced through an addition of an external booster.

The concept of nitrogen oxide storage-reduction (NSR) is a promising aftertreatment technology for reducing NOx emissions from lean-burn engine exhaust. The present work focuses on the first two steps of the overall NSR mechanism, namely, NO to NO 2 oxidation and NOx storage. The governing storage mechanisms are mainly elucidated on the model catalysts such as Pt/Ba/Al 2 O 3 . A unique detailed NO oxidation kinetic model over Pt/Al 2 O 3 was conceived based on literature data and validated over a wide range of experimental conditions. This detailed mechanism was then globalized to obtain a Langmuir-Hinshelwood rate expression, which resulted in a reduced CPU cost in reactor computations. The global oxidation model predicts various experimental NO and NO 2 profiles well. Further, a detailed kinetic model for NOx storage over Ba/Al 2 O 3 was developed and validated against different experimental data. Finally, the detailed oxidation and storage schemes were successfully coupled and species spillover between the noble metal and the storage material was accounted for. The experimental NO and NO 2 profiles obtained from the NOx storage experiments over Pt/Ba/Al 2 O 3 could be reproduced by the detailed coupled model. Reaction pathway analyses and sensitivity studies were performed to provide a more comprehensive insight into the system behavior.

SO(3) -induced surface reconstruction: The SO(3) molecule as a multidentate ligand induces remarkable surface reconstruction phenomena on alkaline earth oxide surface. By using ab initio computations, adsorption properties are derived to elucidate the thermodynamics of the SO(3) -BaO system.