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Identifying the driving processes of Diesel spray injection through mixture fraction and velocity field measurements at ECN Spray A

Universite D'Orleans-Christine Rousselle
Eindhoven University of Technology-Bart Somers
  • Technical Paper
  • 2020-01-0831
To be published on 2020-04-14 by SAE International in United States
Diesel spray mixture formation is investigated at target conditions using multiple diagnostics and laboratories. High speed Particle Image Velocimetry (PIV) is used to measure the velocity field inside and outside the jet simultaneously with a new frame straddling synchronisation scheme. The PIV measurements are carried out in the Engine Combustion Network Spray A target conditions, enabling direct comparisons with mixture fraction measurements previously performed in the same conditions, and forming a unique database at diesel conditions. A 1D spray model, based upon mass and momentum exchange between axial control volumes and near-Gaussian velocity and mixture fraction profiles is evaluated against the data. The 1D spray model quantitatively predicts the main spray characteristics (average mixture fraction and velocity fields) within the measurement uncertainty for a wide range of parametric variations, verifying that a Diesel spray becomes momentum controlled and has a Gaussian profile. A required input to the model is the jet angle, which is obtained experimentally. Although an expected result for a gas jet, this is the first time that combined datasets of velocity and…
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Study on the effects on Diesel LTC combustion of 2-EHN as cetane improver

Universite D'Orleans-Fabrice Foucher
Université d'Orleans-Richard Oung
  • Technical Paper
  • 2020-01-1125
To be published on 2020-04-14 by SAE International in United States
A single cylinder Diesel engine was used to study Diesel and LTC combustion. We evaluated the 2-EthylHexyl Nitrate (2-EHN) as Cetane improver distributed by VeryOne@ on the combustion of six diesel fuel prepared from a low Cetane Number (CN) diesel fuel (CN of 43.7) and two biodiesel mixed at 20% with the low Cetane number diesel fuel : Soybean oil Methyl Ester (SME) and Rapeseed oil Methyl Ester (RME). Each fuels doped with the 2-EHN were prepared to meet the minimum European CN, 51. LTC strategies could provide low NOx emission without thermal efficiency deterioration. The study investigated engine operation at loads of 2, 6 and 10 bar IMEP at engine speed of 1250 rpm, 1500 rpm and 2000 rpm and the impact against synthetic EGR up to 30%. The low-temperature decomposition of 2-EHN, resulting in the oxidation of the fuel, makes it possible to achieve a very low cycle-to-cycle variation of the IMEP even at very low load or at a very high rate of EGR. From kinetic mechanism analysis, we had shown that…
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Performance and Emissions of an Ammonia-Fueled SI Engine with Hydrogen Enrichment

Universite D'Orleans-Pierre BREQUIGNY, Christine Rousselle
Université D'Orleans-Charles Lhuillier
Published 2019-09-09 by SAE International in United States
While the optimization of the internal combustion engine (ICE) remains a very important topic, alternative fuels are also expected to play a significant role in the reduction of CO2 emissions. High energy densities and handling ease are their main advantages amongst other energy carriers. Ammonia (NH3) additionally contains no carbon and has a worldwide existing transport and storage infrastructure. It could be produced directly from renewable electricity, water and air, and is thus currently considered as a smart energy carrier and combustion fuel. However, ammonia presents a low combustion intensity and the risk of elevated nitrogen-based emissions, thus rendering in-depth investigation of its suitability as an ICE fuel necessary.In the present study, a recent single-cylinder spark-ignition engine is fueled with gaseous ammonia/hydrogen/air mixtures at various hydrogen fractions, equivalence ratios and intake pressures. A small hydrogen fraction is used as combustion promoter and might be generated in-situ through NH3 catalytic or heat-assisted dissociation. The in-cylinder pressure and exhaust concentrations of selected species are recorded and analyzed. Results show that ammonia is a very suitable fuel for…
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RCCI Combustion Regime Transitions in a Single-Cylinder Optical Engine and a Multi-Cylinder Metal Engine

SAE International Journal of Engines

Universite D'Orleans-Christine Mounaim Rousselle
Oak Ridge National Laboratory-Martin Wissink, Scott Curran
  • Journal Article
  • 2017-24-0088
Published 2017-09-04 by SAE International in United States
Reactivity Controlled Compression Ignition (RCCI) is an approach to increase engine efficiency and lower engine-out emissions by using in-cylinder stratification of fuels with differing reactivity (i.e., autoignition characteristics) to control combustion phasing. Stratification can be altered by varying the injection timing of the high-reactivity fuel, causing transitions across multiple regimes of combustion. When injection is sufficiently early, combustion approaches a highly-premixed autoignition regime, and when it is sufficiently late it approaches more mixing-controlled, diesel-like conditions. Engine performance, emissions, and control authority over combustion phasing with injection timing are most favorable in between, within the RCCI regime.To study charge preparation phenomena that dictate regime transitions, two different optical diagnostics are applied in a single-cylinder heavy-duty optical engine, and conventional engine diagnostics are applied in a multi-cylinder, light-duty all-metal engine. Both engines are operated with iso-octane and n-heptane as the low- and high-reactivity fuels, respectively. The iso-octane fuel fraction delivers 80% of the total fuel energy, the global equivalence ratio is 0.35, and no exhaust gas recirculation is used. In the optical engine, single-shot, band-pass infrared (IR)…
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Application of an Ozone Generator to Control the Homogeneous Charge Compression Ignition Combustion Process

Universite D'Orleans-Fabrice Foucher, Christine Rousselle
Universite D'Orleans / CNRS-Jean-Baptiste Masurier
Published 2015-09-06 by SAE International in United States
The present investigation examines a new way to control the homogeneous charge compression ignition (HCCI) process. An ozone generator was set up to seed the intake of a single-cylinder engine with low concentrations of ozone. Two kinds of gas supply were tested: an oxygen supply and an air supply; as well as two kinds of injection: a plenum injection and an injection inside one of the intake pipes. The results showed that air can easily be used and that the second injection mode is the best way to achieve an on-road application. Moreover, experiments demonstrated that each combustion parameter such as the phasing, the indicated mean effective pressure and the pollutants can be controlled by varying the capacity of the ozone generator. Then, from experimental results, two dynamic control approaches on the maximum pressure phasing were proposed. A cartography control showed that a fast control of the combustion phasing can be achieved and a closed loop control demonstrated an excellent accuracy. Finally, this investigation demonstrated that an on-road application is achievable and improvements of this…
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Modeling Waves in ICE Ducts: Comparison of 1D and Low Order Models

Universite D'Orleans-Alain Charlet, Yann Chamaillard
Robert Bosch GmbH-Farouq Meddahi, Christian Fleck, Stefan Grodde
Published 2015-09-06 by SAE International in United States
The paper presents a comparative study of various models used to estimate gas dynamics in internal combustion engine (ICE) ducts. 1D models provide a sufficient accuracy, but they are still not implementable on current ECUs. On the other hand, low order models can be real-time but their lack of accuracy and high calibration cost are still a challenging problem.This work aims at presenting a comparison of currently used gas dynamics models to predict transient phenomena in engine ducts. It emphasizes on 1D and low order models. To test under engine-like conditions, the intake path of a virtual engine implemented in GT-Power and a production two cylinder engine are used.Results show a contrast in the performance of the different models, which gives the possibility to evaluate the various approaches. Based on this assessment and depending on the application in hand, the models can be chosen properly to estimate the gas dynamics in internal combustion engine ducts.
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Incorporating Thermo- and Aerodynamic Losses into Compressor Models for Real-Time Applications

Universite D'Orleans-Alain Charlet, Yann Chamaillard
Robert Bosch GmbH-Farouq Meddahi, Christian Fleck
Published 2015-04-14 by SAE International in United States
Compressor models play a major role as they define the boost pressure in the intake manifold. These models have to be suitable for real-time applications such as control and diagnosis and for that, they need to be both accurate and computationally inexpensive. However, the models available in the literature usually fulfill only one of these two competing requirements. On the one hand, physics-based models are often too complex to be evaluated on line. On the other hand, data-based models generally suffer insufficient extrapolation features.To combine the merits of these two types of models, this work presents an extended approach to compressor modeling with respect to thermo- and aerodynamic losses. In particular, the model developed by Martin et al. [1] is augmented to explicitly incorporate friction, incidence and heat transfer losses. The resulting model surpasses the extrapolation properties of data-based models and facilitates the generation of extended lookup tables.In conclusion, the three main advantages of the developed approach are first, a high fitting quality resulting in accurate lookup tables for the real-time application, second, little measurement…
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Thermodiffusive Effect on the Flame Development in Lean Burn Spark Ignition Engine

Universite D'Orleans-Pierre Brequigny, Fabien Halter, Christine Mounaïm-Rousselle, Bruno Moreau
Total Marketing Services-Thomas Dubois
Published 2014-10-13 by SAE International in United States
In Spark Ignition engines, the heat release rate is not only piloted by the mixture reactivity but also by its sensitivity to stretch effects. Only few results can be found in the literature about flame stretch effect in SI engine configurations.For this study, three different fuels (Methane, Propane, Iso-octane) were studied, but at different air-fuel lean mixture conditions, to present almost equivalent laminar flame speeds and thermo-dynamical properties at ignition timing condition. Besides those mixtures present different Lewis numbers which are relevant parameters to describe flame-stretch interactions. Mie-scattering tomography was then performed in an optical Spark Ignition (S.I.) engine. Using a high speed camera, flame propagation images were acquired through the piston. Thermodynamic analyses based on in-cylinder pressure traces were performed to estimate in-cylinder temperature and burnt mass fraction during the engine cycle.From the determination of flame areas, the global flame stretch and an equivalent propagation speed have been then defined and estimated. Results prove that mixtures have the same ranking in terms of flame stretch sensitivities as in the laminar regime. Probability density functions…
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Optimization of Gasoline Partially Premixed Combustion Mode

Universite D'Orleans-Christine Mounaim Rousselle, Fabrice Foucher, Amine labreche
Published 2013-10-14 by SAE International in United States
Recent works have demonstrated the possibility of operating compression ignition engine with high resistance to auto-ignition fuels as gasoline. By using gasoline and dilution by exhaust gas recirculation, compression ignition can reach high efficiencies and low particulate (PM) and NOx emissions. One of the promising strategies to reach this combustion is the Gasoline Partially Premixed Combustion (GPPC) concept. First step of the study was to optimize the run of a single cylinder Diesel engine in GPPC with double injections strategy by change the second injection phasing and EGR level. The optimum in terms of heat release rate and regulated pollutant emissions was obtained for second injection timing around TDC and an EGR level at 30%. To perform future optical techniques to provide analysis of mixture preparation, a surrogate of Gasoline (mixture of Isooctane, N-heptane and Toluene) was tested: first its capacities to ignite as function of intake temperature, pressure and EGR level variation by using HCCI experiment and second, its capacities to ignite by using single direct injection.
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Engine Performances and Emissions of Second-Generation Biofuels in Spark Ignition Engines: The Case of Methyl and Ethyl Valerates

Universite D'Orleans-Christine Mounaïm-Rousselle
Universite d'Orleans-Fabrice Foucher, Fabien Halter
Published 2013-09-08 by SAE International in United States
As an alternative to second generation ethanol, valeric esters can be produced from lignocellulose through levulinic acid. While some data on these fuels are available, only few experiments have been performed to analyze their combustion characteristics under engine conditions. Using a traditional spark ignition engine converted to mono-cylinder operation, we have investigated the engine performances and emissions of methyl and ethyl valerates. This paper compares the experimental results for pure valeric esters and for blends of 20% of esters in PRF95, with PRF95 as the reference fuel. The esters propagate faster than PRF95 which requires a slight change of ignition timing to optimise the work output. However, both the performances and the emissions are not significantly changed compared to the reference. Accordingly, methyl and ethyl valerate represent very good alternatives as biofuels for SI engines. Future studies will focus on testing these esters in real application engines and performing endurance tests.
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