Benoite Lefort | University of Burgundy in Dijon (original) (raw)

Papers by Benoite Lefort

Proceedings of the Combustion Institute, 2020

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Combustion and Flame, 2020

Combustion and Flame, 2018

Ignition delay times of ethanol/DME/air mixtures were measured in a rapid compression machine and... more Ignition delay times of ethanol/DME/air mixtures were measured in a rapid compression machine and in two highpressure shock tubes at conditions relevant to internal combustion engines. The influences of these conditions on the auto-ignition behavior of the mixture blends were systematically investigated. Our results indicate that, in the low temperature range (650-950 K), increasing the amount of DME in the fuel mixture increases. At higher temperatures, reactivity is controlled by ethanol and there is almost no visible impact of the fuel mixture composition, whereas DME shows a slower reactivity. The experimental measurements were simulated using an updated mechanism for ethanol which includes the latest experimental or theoretical work in the literature. Results indicates that the model is in satisfactory agreement with all of the mixtures.

Fuel, 2016

A high pressure shock tube ''HPST" has been designed and validated for the purpose of chemical ki... more A high pressure shock tube ''HPST" has been designed and validated for the purpose of chemical kinetics studies at elevated pressures and temperatures. Using this facility, auto-ignition investigations are conducted for methane at 10, 20 and 40 bar and temperatures from 1400 K up to 2000 K. Three equivalence ratios (/ = 0.5, 1 and 2) for a methane/oxygen/argon mixture were studied in this paper under diluted conditions (argon > 90%). Experimental data showed good agreement with previous literature measurements and predictions from three different chemical kinetic models (Aramco Mech 1.3, USC Mech II and GRI Mech 3.0) commonly used in the literature, which confirms the quality of the experimental data obtained with the new high pressure shock tube and allows the expansion of the validation range of the mechanisms for ignition delay times to higher pressures. The investigations performed to explain the differences observed for ignition delay times predictions highlighted an important sensitivity of the USC mechanism predictions to equivalence ratio and an important sensitivity to CH 3 + O 2 reactions. Finally, the impact of pressure and equivalence ratio on ignition delay time is evaluated over a broad range of pressure (1-50 bar) and equivalence ratio (/ = 0.2-3).

Journal of Renewable and Sustainable Energy, 2012

Until now, the major problem of methane conversion is to break the very strong C-H bond. It is po... more Until now, the major problem of methane conversion is to break the very strong C-H bond. It is possible by employing some catalytic methods. However, the formation of carbon powder diminishes the catalytic performance. The use of a gliding arc, described in this work, has two objectives: the hydrogen production and other syngas such as acetylene, and the treatment of the green house gas methane. A good approximation model describing the chemical processes concerning the methane decomposition is described, first by the interaction of key radicals such as CH3 and H, followed by chemical reactions involving other hydrocarbons. Furthermore, the experimental results demonstrated the ability of the gliding arc to accelerate chemical reactions at low temperatures while decreasing energetic cost.

Combustion and Flame, 2012

ABSTRACT New experimental results for the oxidation of n-butylbenzene, a component of diesel fuel... more ABSTRACT New experimental results for the oxidation of n-butylbenzene, a component of diesel fuel, have been obtained using three different devices. A rapid compression machine has been used to measure autoignition delay times after compression at temperatures in the range 640–960 K, at pressures from 13 to 23 bar, and at equivalence ratios from 0.3 to 0.5. Results show low-temperature behavior, with the appearance of cool flames and a negative temperature coefficient (NTC) region for the richest mixtures. To investigate this reaction at higher temperatures, a shock tube has been used. The shock tube study was performed over a wide range of experimental temperatures, pressures, and equivalence ratios, with air used as the fuel diluent. The ignition temperatures were recorded over the range 980–1740 K, at reflected shock pressures of 1, 10, and 30 atm. Mixtures were investigated at equivalence ratios of 0.3, 0.5, 1.0 and 2.0 in order to determine the effects of fuel concentration on reactivity over the entire temperature range. Using a jet-stirred reactor, the formation of numerous reaction products has been followed at temperatures from 550 to 1100 K, at atmospheric pressure, and at equivalence ratios of 0.25, 1.0, and 2.0. Slight low-temperature reactivity (below 750 K) with a NTC region has been observed, especially for the leanest mixtures. A detailed chemical kinetic model has been written based on rules similar to those considered for alkanes by the system EXGAS developed at Nancy. Simulations using this model have been compared to the experimental results presented in this study, but also to results in the literature obtained in a jet-stirred reactor at 10 bar, in the same rapid compression machine for stoichiometric mixtures, in a plug flow reactor at 1069 K and atmospheric pressure, and in a low-pressure (0.066 bar) laminar premixed methane flame doped with n-butylbenzene. The observed agreement is globally better than that obtained with models from the literature. Flow rate and sensitivity analyses have revealed a preponderant role played by the addition to molecular oxygen of resonantly stabilized, 4-phenylbut-4-yl radicals.

Proceedings of the Combustion Institute, 2020

HAL (Le Centre pour la Communication Scientifique Directe), Jun 18, 2018

Le Centre pour la Communication Scientifique Directe - HAL - memSIC, Nov 7, 2017

HAL (Le Centre pour la Communication Scientifique Directe), Sep 5, 2017

HAL (Le Centre pour la Communication Scientifique Directe), Jul 22, 2018

HAL (Le Centre pour la Communication Scientifique Directe), Aug 1, 2006

International audienc

82 ZREE N°1/2019 DOSSIER MOBILITE PROPRE Pierre Romet, Franck Gechter UTBM F-90010 Belfort Cedex... more 82 ZREE N°1/2019 DOSSIER MOBILITE PROPRE Pierre Romet, Franck Gechter UTBM F-90010 Belfort Cedex El-Hassane Aglzim Benoite Lefort Sidi-Mohammed Senouci DRIVE Lab, Univ. Bourgogne Franche-Comte, Nevers, France La place du vehicule autonome dans une mobilite propre As part of the essential components related to the digital revolution, the auto- nomous vehicle is the ﬂagship deemed to change drastically our habits in terms of mobility. Besides the expected important improvements in terms of security, the autonomous vehicle should provide an impact on the environ- mental level as well. This article gives an overview of current and long-term advances expected concerning the autonomous vehicle concept. Parmi les elements principaux lies a la revolution du numerique, le vehicule autonome fait ﬁgure de porte-drapeau destine a faire evoluer drastiquement nos habitudes en matiere de mobilite. Outre des progres importants atten- dus en terme de securite, le vehicule autonome doit egalement ap...

The gasification of a droplet via vaporization is one of the main processes in combustion systems... more The gasification of a droplet via vaporization is one of the main processes in combustion systems, namely diesel and propulsion engines. In these combustion systems, always the liquid fuel is atomized as a cloud of droplets in the chamber, which then vaporizes, and mixes with the oxidant and burns to release heat. Therefore, to afford a better knowledge especially in modelling complex spray flows and mixture formation issues, the study of the droplet vaporization which involves mass, heat and momentum transfer processes is really vital. Alcohol has been chosen for this particular study due to its potential as an alternative fuel to the current conventional hydrocarbon fuel. However, viability of alcohols as alternate fuels has been limited by their high latent heat of vaporization and low heating value which can deliver difficulty in providing rapid gasification, mixing and ignition. Consequently, the objective of this study is to provide more data and understanding in alcohols vaporization behaviour. Methanol and ethanol have been studied extensively in terms of fundamental issues such as vaporization, in engine performances and pollutants formation. However, the potential is now extended and shifted on propanol, which has a better energy density and lower affinity with water than methanol and ethanol. A detailed description of the vaporization of an isolated droplet has been realized in this experimental study aimed at investigating another aliphatic alcohol, 1-propanol. This investigation extended our previous study on ethanol droplet vaporization to 1-propanol that is known as always less volatile, but holds higher boiling point than ethanol. The characterization of the vaporization phenomenon is necessary for this liquid fuel to develop efficient design of injection systems for propulsion and power generation. Particularly, the vaporization rates and their dependency on temperature, important features for modeling and design, are explored for 1-propanol for the first time at high temperatures. The experimental set-up consists of a pressure chamber in which the furnace, the droplet formation, the droplet support and motion devices are located. To minimize the influence of the droplet supporting system, a cross quartz fibers (14 μm) configuration has been used. A 1-propanol droplet is located at the intersection of the cross with a controlled initial diameter (400 – 600 μm). Ambient temperature is varied from 298 to 973 K, whereas the ambient pressure is maintained at atmospheric pressure. The temporal evolution of the droplet squared diameter of 1-propanol exhibits a quasi-steady behaviour. The result shows that the d2-law is apparently obeyed and a constant vaporization rate is achieved. The histories of the instantaneous vaporisation rates calculated from the d² (t) curves which are almost always a constant confirm this quasi stationary aspect of the phenomenon. However, as the ambient temperature increased beyond 673 K, the instantaneous vaporization rate decreases slightly during the droplet lifetime. It could be said that at higher temperatures, the vaporization of 1- propanol droplet show a slightly different behaviour.

Revista Internacional De Contaminacion Ambiental, Mar 21, 2013

A high pressure shock tube "HPST" has been designed for the purpose of chemical kinetics studies ... more A high pressure shock tube "HPST" has been designed for the purpose of chemical kinetics studies at elevated pressures and temperatures. The present HPST is designed as a versatile tool and includes the features of a fast compression, optical accessibility, and capability for specie measurement. Characterization experiments establish the suitability of the tube for chemical kinetic studies and show that highly repeatable experimental conditions up to 40 bar and temperatures between 1300 and 2000 K can be obtained. As well, tailoring gas mixture in the driver section, used to obtain a longer test time, is studied in the characterization experiments. Using this facility, autoignition investigations are conducted for methane mixture (1% CH 4 ; 4% O 2 ; 95% Ar ; f=0,5) at 10, 20 and 40 bar pressures and temperatures from 1300 K up to 2000 K.

Revista Internacional de Contaminacion Ambiental

Nowadays, diesel engines are greatly developed in automobiles allowing the reductions of carbon d... more Nowadays, diesel engines are greatly developed in automobiles allowing the reductions of carbon dioxide emissions (CO2); however high emissions of particulate matter (MP) and nitric oxides (NOX) still remain. A technology based on non-thermal plasma to diminish toxic emissions is exposed in this work. From previous experimental and simulation results, a chemical mechanism is proposed showing a rapidly diminution of MP and NOX, in presence of plasma.

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2011

Chemically activated decompositions are generally neglected in the quantitative description of hi... more Chemically activated decompositions are generally neglected in the quantitative description of high temperature processes such as hydrocarbon combustion. This paper considers the rate constants for the following processes; Aromatic Radical + Methyl <=> AromaticCH 3 + => AromaticCH 2 + H M + AromaticCH 3 where M is the collision partner and aromaticCH 3 is toluene, 1-methylnaphthalene or 1-methylphenanthrene. Rate constants are derived over a range of temperatures and pressures. Primary interest is focused on the effect of molecular size on temperature as well as pressure dependent rate constants.. Results are based on the toluene system where comparisons can be made with experimental data and ab initio and RRKM calculations from the literature. A general strategy for deriving rate constants for chemical activated as well as thermal reactions, which is readily extendable to larger molecules, has been validated. The special feature of these reactions is the formation of resonance stabilized aromatic molecules. The results demonstrate the necessity of considering chemical activation processes in most of the cases where excited adducts are formed. These include oxygen addition to radicals as well as soot formation processes involved in ring growth. Chemical activation processes are intimately related to thermal process and their inclusion in current databases where thermal processes are properly represented is mandatory.

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Wind Turbine Technology, 2011

The study of the gasification of a droplet via vaporization, which involves heat, mass and moment... more The study of the gasification of a droplet via vaporization, which involves heat, mass and momentum transfer processes in gas and liquid phases, and their coupling at the droplet interface, is necessary for better understanding and modeling of complex spray and mixture formation issues. A detailed description of the vaporization of an isolated droplet has been realized in this experimental study aimed at investigating the impact of the water vapor contained in the surrounding gas on the evaporation of an ethanol droplet. The experimental set-up consists of a heated chamber with a cross quartz fibers configuration as droplet support. An ethanol droplet is located at the intersection of the cross with a controlled initial diameter (300–550μm). Ambient temperature is varied from 350 to 850 K. The real impact of the water concentration on the vaporization rate of an ethanol droplet in a large range of temperature is examined, showing that the vaporization of an ethanol droplet is accomp...

Proceedings of the Combustion Institute, 2020

Combustion and Flame, 2020

Combustion and Flame, 2018

Fuel, 2016

Journal of Renewable and Sustainable Energy, 2012

Combustion and Flame, 2012

Proceedings of the Combustion Institute, 2020

HAL (Le Centre pour la Communication Scientifique Directe), Jun 18, 2018

Le Centre pour la Communication Scientifique Directe - HAL - memSIC, Nov 7, 2017

HAL (Le Centre pour la Communication Scientifique Directe), Sep 5, 2017

HAL (Le Centre pour la Communication Scientifique Directe), Jul 22, 2018

HAL (Le Centre pour la Communication Scientifique Directe), Aug 1, 2006

International audienc

Revista Internacional De Contaminacion Ambiental, Mar 21, 2013

Revista Internacional de Contaminacion Ambiental

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2011

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Wind Turbine Technology, 2011