Evaluation of Modeling Approaches for NOx Formation in a Common-Rail DI Diesel Engine within the Framework of Representative
Interactive Flamelets (RIF)

Felsch, C.; Gauding, Michael; Vanegas, A.; Won, Hyun Woo; Luckhchoura, V.; Peters, N.; Hasse, Christian; Ewald, Jens

doi:10.4271/2008-01-0971

Cited by 7 publications

(6 citation statements)

References 27 publications

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“…Good results were obtained with this model on diesel engine configurations. 8,9 Although it presents a reduced CPU cost compared with the two previous approaches, it can become expensive compared with tabulated chemistry approaches for very complex chemical mechanisms including hundreds of species and thousands of reactions.…”

Section: Introductionmentioning

confidence: 99%

A tabulated diffusion flame model applied to diesel engine simulations

Michel

Colin

2013

International Journal of Engine Research

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The tabulated diffusion flamelet model approximated diffusion flame-presumed conditional moment is here adapted to the Reynolds-averaged Navier–Stokes simulation of diesel engines. The first model modification concerns the effects of variable pressure, which are necessary to retrieve the chemical species concentrations during the expansion stroke. They are accounted for following an approach similar to the variable volume tabulated homogeneous chemistry approach. The second model modification concerns the local fresh gases temperature stratification modeling that needs to be included due to the liquid injection and is based on the transport equation for the fresh gases enthalpy conditioned in the air. The resulting model is called engine approximated diffusion flames and is able to account for the auto-ignition of the diffusion flame, the local mixture fraction heterogeneity through a presumed probability density function, complex chemistry effects, variable pressure, and temperature stratification. As a first validation, an ideal homogeneous adiabatic engine is computed and successfully compared with the reference solution of the same case obtained with a kinetic solver. Then, six diesel engine operating points at various loads, engine speeds, and dilutions are simulated and compared with experimental measurements. It is shown that the proposed model correctly reproduces the mean pressure evolution and gives a correct estimation of the CO mass fraction. Furthermore, coupled to the NO relaxation approach model, relatively accurate NO predictions are obtained. Finally, different simplified formulations of engine approximated diffusion flames are evaluated, showing that all model components are necessary to correctly estimate the pressure evolutions and pollutant emissions.

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Section: Introductionmentioning

confidence: 99%

A tabulated diffusion flame model applied to diesel engine simulations

Michel

Colin

2013

International Journal of Engine Research

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“…In such case, evolution of NO depends on flamelet temperature history and mixture fraction distribution. This model neglects the time-scales which are typical of NO formation: as a consequence of this, predicted NO concentrations are higher than the ones of the other tested approaches and also of experimental data as reported in Felsch et al 19 Soot emissions. The semi-empirical model proposed by Lindstedt and colleagues 20 is used to estimate soot emissions: two transport equations for soot particle number density N p and volume fraction f v are solved, with source terms related to nucleation, coagulation, surface growth and oxidation processes as follows…”

Section: Prediction Of Pollutant Emissionsmentioning

confidence: 91%

Section: Prediction Of Pollutant Emissionsmentioning

confidence: 92%

“…Evolution of NO inside the cylinder is related to fuel and temperature distributions with the maximum concentrations expected in the high-temperature regions and where the mixture fraction is close to the stoichiometric value. To take such aspects into account, different approaches were proposed in the past [7] and three different methods were implemented in Lib-ICE and compared in this work.…”

Section: Prediction Of Pollutant Emissionsmentioning

confidence: 99%

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A comprehensive methodology for computational fluid dynamics combustion modeling of industrial diesel engines

Lucchini

Torre

Onorati

et al. 2017

International Journal of Engine Research

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• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Link to publication• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract. Combustion control and optimization is of great importance to meet future emission standards in Diesel engines: increase of bmep at high loads and extension of the operating range of advanced combustion modes seem to be the most promising solutions to reduce fuel consumption and pollutant emissions at the same time. Within this context, detailed CFD tools are required to predict the different involved phenomena such as fuel-air mixing, unsteady diffusion combustion and formation of noxious species. Detailed kinetics, consistent spray models and high quality grids are necessary to perform predictive simulations which can be used either for design or diagnostic purposes. In this work, the authors present a comprehensive approach which was developed using an open-source CFD code. To minimize the pre-processing time and preserve results accuracy, algorithms for automatic mesh generation of spray-oriented grids were developed and successfully applied to different combustion chamber geometries. The Lagrangian approach was used to describe the spray evolution while the combustion process is modeled employing detailed chemistry and, eventually, considering turbulence/chemistry interaction. The proposed CFD methodology was first assessed considering inert and reacting experiments in a constant volume vessel, where operating conditions typical of heavy duty Diesel Engines were reproduced. Afterwards, engine simulations were performed considering two different load points and two piston bowl geometries, respectively. Experimental validation was carried out by comparing computed and experimental data of in-cylinder pressure, heat release rate ...

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“…For NO x , however, different approaches have been employed. First of all, NO is chosen to represents NO x and the Extended Zeldovich mechanism is used to model the formation of NO [17]. Since the formation of NO has relatively larger time scale compared to other species, including the NO mechanism in the flamelet library and direct integration of its β-PDF into CFD domain leads to over-prediction of NO concentration.…”

Section: Modelling Pollutant Emissionsmentioning

confidence: 99%

A Numerical Study on the Sensitivity of Soot and NOx Formation to the Operating Conditions in Heavy Duty Engines

Fatehi¹,

Wingren²,

Lucchini

et al. 2018

SAE Technical Paper Series

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I n this paper, computation fluid dynamics (CFD) simulations are employed to describe the effect of flow parameters on the formation of soot and NO x in a heavy duty engine under low load and high load. The complexity of diesel combustion, specially when soot, NO x and other emissions are of interest, requires using a detailed chemical mechanism to have a correct estimation of temperature and species distribution. In this work, Multiple Representative Interactive Flamelets (MRIF) method is employed to describe the chemical reactions, ignition, flame propagation and emissions in the engine. A phenomenological model for soot formation, including soot nucleation, coagulation and oxidation with O2 and OH is incorporated into the flamelet combustion model. Different strategies for modelling NO x are chosen to take into account the longer time scale for NO x formation. The numerical results are compared with experimental data to show the validity of the model for the cases under study. A good agreement is achieved between the model results and the pressure and heat release rate from the experiment. For soot and NO x , the model is able to correctly predict the trends between different cases. The effect of number of RIFs on the behaviour of the model is discussed. Downloaded from SAE International by Politecnico di Milano, Thursday, April 11, 2019 © SAE InternationalFIGURE 7 g/kWh of soot at the exhaust of the engine. Comparison between the model and the experiment.FIGURE 9 (a) Scatter plot of scalar dissipation rate in T-Z coordinate for HL1 cases, comparison between 1 and 12 RIFs, (b) Number of cells in the CFD domain for each T-Z point © SAE InternationalFIGURE 10 Soot volume fraction, soot formation and soot oxidation at 3 different time instances. © SAE International Downloaded from SAE International by Politecnico di Milano, Thursday, April 11, 2019 FIGURE 13 g/kWh of NO x at the exhaust of the engine. Comparison between the model and the experiment. © SAE International FIGURE 14 Mass fraction of NO vs temperature at 363 CAD for HL2 case; Behaviour of different modelling strategies on the NO formation.All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE International.Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE International. The author is solely responsible for the content of the paper.

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Evaluation of Modeling Approaches for NOx Formation in a Common-Rail DI Diesel Engine within the Framework of Representative Interactive Flamelets (RIF)

Cited by 7 publications

References 27 publications

A tabulated diffusion flame model applied to diesel engine simulations

A tabulated diffusion flame model applied to diesel engine simulations

A comprehensive methodology for computational fluid dynamics combustion modeling of industrial diesel engines

A Numerical Study on the Sensitivity of Soot and NOx Formation to the Operating Conditions in Heavy Duty Engines

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