A New 0D Diesel HCCI Combustion Model Derived from a 3D CFD Approach with Detailed Tabulated Chemistry

This paper presents a new 0D phenomenological approach to the numerical modelling of Diesel HCCI combustion. The model is obtained through the reduction of TKI-PDF (Tabulated Kinetics for Ignition, coupled with presumed Probability Density Function) 3D CFD model developed at the IFP. Its formulation is based on physical considerations, to take into account the main phenomena and their mutual interactions that take place in the cylinder during the combustion process. Aspects relating to spray penetration, fuel evaporation, turbulence, mixture formation and chemical kinetics have been studied in detail. The original contribution of this work concerns the modelling of the formation and evolution of the equivalence ratio stratification around the spray, and of its connection to combustion kinetics. In order to achieve this, different tools commonly adopted in 3D modelling have been adapted to 0D modelling. Presumed PDF theory has been extended to a 0D formalism in order to characterize the mixture-fraction distribution. This approach has then been coupled with droplet-evaporation theory in order to have access to the thermodynamic conditions characterizing the mixture. The temporal evolution of the spray is computed in terms of volume and the entrained mass of gases, starting from conservation laws for mass, momentum and energy. An adapted $\kappa-\epsilon$ model is used to take into account the turbulence in the cylinder, which is very important, in an ICE (Internal Combustion Engine), especially during the mixing process. Further, combustion heatrelease is computed using an adapted detailed tabulated chemistry method inspired by the FPI (Flame Prolongation of ILDM (Intrinsic Low Dimensional Manifold)) theory. This look-up table allows the simulation of a large range of combustion regimes, since it takes into account the presence of EGR (Exhaust Gas Recirculation) in the mixture. The results of the 0D model are compared in an initial step to the 3D CFD results. Finally, the OD model is validated against a wide experimental database

0D Modelling: a Promising Means for After-treatment Issues in Modern Automotive Applications

For modern automotive applications, after-treatment systems have become essential to respect the new emission standards. All the automotive world's attention is focused on catalysis systems because they seem to be one of the best ways to reach the future standards. As a result, after-treatment issues are more and more significant in the cost of the whole engine and vehicle development process. For example, the Euro 6 Diesel after-treatment line might for some applications be composed of nothing less than five distinct after-treatment bricks. This complex architecture implies developing advanced tools to help the exhaust line conception and also the design of associated control strategies. The present paper demonstrates that zero-dimensional (0D) simulation can be a relevant approach to develop exhaust line simulators compatible with accuracy and CPU time required performances. This paper proposes an original zero-dimensional model of the monolith. This approach is based on resistive and capacitive elements according to the bond graph theory [Karnopp D.C., Margolis D.L., Rosenberg R.C. (1990) Systems dynamics: a unified approach, Second Edition, John Wiley & Sons, New-York]. The described dynamic model takes into account the pneumatic flow and the thermal behaviour of the monolith. Models of several catalysts are built by plugging this monolith model with some well-known simplified chemical reaction schemes [Koltsakis G.C., Konstandinis P.A., Stamatelos A.M. (1997) Development and application range of mathematical models for 3-way catalytic converters, Appl. Catal. B: Environ. 12, 161-191]. Splitting a monolith model into several elementary zero-dimensional blocks in series allows having a good representation of the specific internal dynamic of one catalyst and to access some local information as in conventional well-known one-dimensional models with low CPU time cost [Koltsakis G.C., Konstandinis P.A., Stamatelos A.M. (1997) Development and application range of mathematical models for 3-way catalytic converters, Appl. Catal. B: Environ. 12, 161-191]. Such an approach can be used as a way to get a phenomenological understanding of the catalytic system, which is known to be a very complex multi-physical system. It also represents a relevant simulation tool for the definition of after-treatment line architecture and pollutant emission control. The approach's potential to deal with all modern after-treatment bodies is illustrated by results for a Three-Way Catalyst (3WC), a Diesel Oxidation Catalyst (DOC), a Lean NOx Trap (LNT) system, a Selective Catalyst Reduction of NOx (SCR) system and a Diesel Particulate Filter (DPF). This ability to give, with a good compromise between accuracy/low CPU time cost, some interesting information to help the development of more and more complex exhaust system makes zero-dimensional simulation relevant

Rapport final du projet VECSim. Rapport de synthèse

Ce document constitue le rapport final du projet VECSim, projet de développement dans l'environnement AMESim, d'outils de simulation de la consommation et des émissions polluantes des Îhicules conventionnels et hybrides. Il présente une synthèse de tous les travaux réalisés dans le projet concernant le développement des librairies IFP-Drive, dédiée à la simulation globale des Îhicules, IFPEngine, dédiée à la simulation détaillée du moteur thermique, IFP-Exhaust dédiée à la simulationdétaillée de la ligne d'échappement et des modèles de motorisation électrique, de stockage électrique (batterie et de supercapacité). Plusieurs cas de validation représentatifs des applications réelles et mettant en valeur le caractère interopérables de ces outils, sont également proposés : Toyota Prius versions 1 et 2, Honda Insight, Îhicule à moteur essence suralimenté, Îhicule à moteur Diesel suralimenté, Îhicule hybride à moteur GNV suralimenté