The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Jonathan Chauvin - One of the best experts on this subject based on the ideXlab platform.
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CDC - Control of a turbocharged Diesel engine fitted with high pressure and low pressure exhaust Gas recirculation systems
Proceedings of the 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference, 2009Co-Authors: Olivier Grondin, Philippe Moulin, Jonathan ChauvinAbstract:Exhaust Gas recirculation is an effective way for reducing nitric oxides emissions in Diesel engine achieving low temperature combustion (LTC). Two strategies can be applied to recirculate Burnt Gas in a turbocharged Diesel engine using the high pressure loop or the low pressure loop. This paper describes a generic model based control structure for Diesel engines with dual-loop exhaust Gas recirculation (EGR) and variable geometry turbocharger. An observer is designed to estimate the exhaust Gas flow coming from the high pressure loop or from the low pressure loop. These estimates are used for the intake Burnt Gas fraction control. This approach avoids direct measurement or implementation of additional sensors. In addition, a generic model based control based on motion planning is adapted to the low pressure EGR system. The main advantage of the approach is that turbocharger and exhaust Gas recirculation systems controllers have a limited number of calibration parameters. The observer and controller results are presented and validated on a LTC-Diesel engine with a dual-loop EGR system.
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Control of a turbocharged Diesel engine fitted with high pressure and low pressure exhaust Gas recirculation systems
Proceedings of the 48h IEEE Conference on Decision and Control CDC held jointly with 2009 28th Chinese Control Conference, 2009Co-Authors: Olivier Grondin, Philippe Moulin, Jonathan ChauvinAbstract:Exhaust Gas recirculation is an effective way for reducing nitric oxides emissions in Diesel engine achieving low temperature combustion (LTC). Two strategies can be applied to recirculate Burnt Gas in a turbocharged Diesel engine using the high pressure loop or the low pressure loop. This paper describes a generic model based control structure for Diesel engines with dual-loop exhaust Gas recirculation (EGR) and variable geometry turbocharger. An observer is designed to estimate the exhaust Gas flow coming from the high pressure loop or from the low pressure loop. These estimates are used for the intake Burnt Gas fraction control. This approach avoids direct measurement or implementation of additional sensors. In addition, a generic model based control based on motion planning is adapted to the low pressure EGR system. The main advantage of the approach is that turbocharger and exhaust Gas recirculation systems controllers have a limited number of calibration parameters. The observer and controller results are presented and validated on a LTC-Diesel engine with a dual-loop EGR system.
Laurie Goldsworthy - One of the best experts on this subject based on the ideXlab platform.
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Real time model for oxides of nitrogen emissions from a slow speed marine diesel
Journal of Marine Engineering & Technology, 2003Co-Authors: Laurie GoldsworthyAbstract:A thermodynamic model is presented for predicting oxides of nitrogen (NOx) emissions from slow speed marine diesel engines. The model is zero-dimensional, uses chemical kinetics for NOx formation in multiple Burnt Gas zones, and runs in real time on a standard PC. The mean fuel/air mixture strength at which NOx forms and the rate of dilution of the Burnt Gas by unBurnt air, are adjustable. Two MAN B&W IMO NOx-compliant slow speed diesels are modelled. Effects such as variations in fuel spray interaction with load are accounted for in the calibration of the model. The effect of dilution rate and equivalence ratio on NOx formation is studied. It is shown that, under certain conditions, there is a critical Burnt Gas dilution rate which maximises NOx. The model responds adequately to changes in engine load and to NOx control measures such as water injection, injection timing retard, exhaust Gas recirculation and humidification.
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Reduced Kinetics Schemes for Oxides of Nitrogen Emissions from a Slow-Speed Marine Diesel Engine
Energy & Fuels, 2003Co-Authors: Laurie GoldsworthyAbstract:A number of reduced chemical kinetics schemes are compared for prediction of NOx emissions from a slow-speed marine diesel engine, using a zero-dimensional model. The kinetic evolution of NO is tracked in 10 representative parcels of Burnt Gas, formed sequentially during combustion. Dilution of the Burnt Gas by unBurnt air is accounted for. The model is developed for use in a machinery space simulator for training marine engineers and in a predictive emissions monitoring system. It runs in real time on a standard PC and requires experimental data for calibration. Kinetics schemes modeled include the extended Zeldovich mechanism and five schemes involving nitrous oxide. The addition of nitrous oxide reactions to the extended Zeldovich mechanism increases predicted NOx by up to 15%. The N2O reactions which give the most significant contribution to NOx in the context of a large marine diesel engine have been identified. NO from fuel bound nitrogen is likely to be significant for engines operating on residual fuel oil.
Olivier Grondin - One of the best experts on this subject based on the ideXlab platform.
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CDC - Control of a turbocharged Diesel engine fitted with high pressure and low pressure exhaust Gas recirculation systems
Proceedings of the 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference, 2009Co-Authors: Olivier Grondin, Philippe Moulin, Jonathan ChauvinAbstract:Exhaust Gas recirculation is an effective way for reducing nitric oxides emissions in Diesel engine achieving low temperature combustion (LTC). Two strategies can be applied to recirculate Burnt Gas in a turbocharged Diesel engine using the high pressure loop or the low pressure loop. This paper describes a generic model based control structure for Diesel engines with dual-loop exhaust Gas recirculation (EGR) and variable geometry turbocharger. An observer is designed to estimate the exhaust Gas flow coming from the high pressure loop or from the low pressure loop. These estimates are used for the intake Burnt Gas fraction control. This approach avoids direct measurement or implementation of additional sensors. In addition, a generic model based control based on motion planning is adapted to the low pressure EGR system. The main advantage of the approach is that turbocharger and exhaust Gas recirculation systems controllers have a limited number of calibration parameters. The observer and controller results are presented and validated on a LTC-Diesel engine with a dual-loop EGR system.
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Control of a turbocharged Diesel engine fitted with high pressure and low pressure exhaust Gas recirculation systems
Proceedings of the 48h IEEE Conference on Decision and Control CDC held jointly with 2009 28th Chinese Control Conference, 2009Co-Authors: Olivier Grondin, Philippe Moulin, Jonathan ChauvinAbstract:Exhaust Gas recirculation is an effective way for reducing nitric oxides emissions in Diesel engine achieving low temperature combustion (LTC). Two strategies can be applied to recirculate Burnt Gas in a turbocharged Diesel engine using the high pressure loop or the low pressure loop. This paper describes a generic model based control structure for Diesel engines with dual-loop exhaust Gas recirculation (EGR) and variable geometry turbocharger. An observer is designed to estimate the exhaust Gas flow coming from the high pressure loop or from the low pressure loop. These estimates are used for the intake Burnt Gas fraction control. This approach avoids direct measurement or implementation of additional sensors. In addition, a generic model based control based on motion planning is adapted to the low pressure EGR system. The main advantage of the approach is that turbocharger and exhaust Gas recirculation systems controllers have a limited number of calibration parameters. The observer and controller results are presented and validated on a LTC-Diesel engine with a dual-loop EGR system.
Bruno Denet - One of the best experts on this subject based on the ideXlab platform.
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Asymptotic analysis of the critical dynamics of spherical Gaseous detonations
Journal of Fluid Mechanics, 2021Co-Authors: Paul Clavin, Raúl Hernández Sánchez, Bruno DenetAbstract:The critical dynamics of supersonic combustion waves is studied in the context of the direct initiation of detonation in a spherical geometry. The study is performed by an asymptotic analysis in the limit of small heat release, including unsteadiness, curvature and the gradient of the Burnt-Gas flow. Derivation of analytical expressions for the rarefaction wave in the Burnt-Gas flow, combined with numerical studies, provides the basis of the analysis. The critical trajectories ‘detonation velocity vs front radius’ D (r f ) are characterized by a decay well below the Chapman–Jouguet (CJ) velocity at a small radius (however, larger than the detonation thickness), followed by a re-acceleration process back to a CJ detonation. The phenomenon is explained by the dynamics of the sonic point inside the inert rarefaction wave behind the reaction zone. The key mechanism is a critical slowdown as soon as the sonic condition (relative to the lead shock) approaches the reaction zone from behind, leading to an increase of the time delay in the nonlinear response of the combustion wave to the rarefaction-wave-induced decay. Detonation fails if the rate of decay is strong enough to prevent the sonic point catching the reaction zone. Concerning successful initiation, the link between the trajectories D (r f ) of the fully unsteady problem and of the self-similar CJ solution of the discontinuous model is deciphered in the long-time limit.
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Analytical study of the direct initiation of Gaseous detonations for small heat release.
Journal of Fluid Mechanics, 2020Co-Authors: Paul Clavin, Bruno DenetAbstract:An analysis of the direct initiation of Gaseous detonations in a spherical geometry is presented. The full set of constitutive equations is analysed by an asymptotic analysis in the double limit of Mach number close to unity (small heat release) and large thermal sensitivity. The quasi-steady curvature-induced quenching phenomenon is first revisited in this limit. Considering a realistic decrease rate of the rarefaction wave, the unsteady problem is reduced to a single nonlinear hyperbolic equation. The time-dependent velocity of the lead shock is an eigenfunction of the problem when two boundary conditions are imposed to the flow at the lead shock and at the Burnt Gas side. Following (Linan et al. , C. R. Mec. , vol. 340, 2012, pp. 829–844), the boundary condition in the quasi-transonic flow of Burnt Gas is expressed in terms of the curvature. Focusing our attention on successful initiation, the time-dependent velocity of the lead shock of a detonation approaching the Chapman–Jouguet regime is the solution of a nonlinear integral equation investigated for stable and marginally unstable detonations. By comparison with the quasi-steady trajectories in the phase space ‘propagation velocity versus radius’, the solution exhibits the unsteady effect produced upon the detonation decay by the long time delay of the upstream-running mode for transferring the rarefaction-wave-induced deceleration across the inner detonation structure from the Burnt Gas to the lead shock. In addition, a new and intriguing phenomenon concerning pulsating detonations is described. Even if the results are not quantitatively accurate, they are qualitatively relevant for real detonations.
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Analytical study of the direct initiation of Gaseous detonations for small heat release.
Journal of Fluid Mechanics, 2020Co-Authors: Paul Clavin, Bruno DenetAbstract:An analysis of the direct initiation of Gaseous detonations in a spherical geometry is presented. The full set of constitutive equations is analysed by an asymptotic analysis in the double limit of Mach number close to unity (small heat release) and large thermal sensitivity. The quasi-steady curvature-induced quenching phenomenon is first revisited in this limit. Considering a realistic decrease rate of the rarefaction wave, the unsteady problem is reduced to a single nonlinear hyperbolic equation. The time-dependent velocity of the lead shock is an eigenfunction of the problem when two boundary conditions are imposed to the flow at the lead shock and at the Burnt Gas side. Following (Liñan et al., C. R. Méc., vol. 340, 2012, pp. 829–844), the boundary condition in the quasi-transonic flow of Burnt Gas is expressed in terms of the curvature. Focusing our attention on successful initiation, the time-dependent velocity of the lead shock of a detonation approaching the Chapman–Jouguet regime is the solution of a nonlinear integral equation investigated for stable and marginally unstable detonations. By comparison with the quasi-steady trajectories in the phase space ‘propagation velocity versus radius’, the solution exhibits the unsteady effect produced upon the detonation decay by the long time delay of the upstream-running mode for transferring the rarefaction-wave-induced deceleration across the inner detonation structure from the Burnt Gas to the lead shock. In addition, a new and intriguing phenomenon concerning pulsating detonations is described. Even if the results are not quantitatively accurate, they are qualitatively relevant for real detonations.
Yasuhiro Ogami - One of the best experts on this subject based on the ideXlab platform.
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dilution effects of superheated water vapor on turbulent premixed flames at high pressure and high temperature
PROCEEDINGS OF THE COMBUSTION INSTITUTE, 2009Co-Authors: Hideaki Kobayashi, Soichiro Yata, Yasuhisa Ichikawa, Yasuhiro OgamiAbstract:Abstract Methane/air turbulent premixed flames diluted with superheated water vapor at high-pressure and high-temperature were experimentally investigated to explore the effects of recycled water vapor on turbulent flame characteristics from the viewpoint of applying high-temperature air combustion (HiTAC) to high-load combustors as well as elucidating those effects of exhaust Gas recirculation (EGR) in IC engine. A newly devised water evaporator was installed in a high-pressure chamber and superheated water vapor was successfully supplied to air up to 1.0 MPa and 573 K. The maximum dilution ratio defined as the ratio of the molar fraction of H 2 O to those of air and H 2 O was 0.1. Turbulent burning velocity, mean volume and the structure of the turbulent flame region were compared with those of flames diluted with CO 2 , reported previously, which is another major species in recycled Burnt Gas. Results showed that the effects of superheated water vapor dilution on turbulent burning velocity, S T , normalized by laminar burning velocity, S L , was much weaker than that of CO 2 dilution. The mean volume of the turbulent flame region defined as the region between 〈 c 〉 = 0.1 and 〈 c 〉 = 0.9, was scarcely changed either. This means that the effects of recycled Burnt Gas on the structure of turbulent premixed flames at high pressure and high-temperature is predominated by CO 2 but not by superheated water vapor, indicating that suppression of combustion oscillation in premixed-type Gas-turbine combustors by extension of the volume of heat release region is due to recycled CO 2 . The emission indices of CO and NO x were also measured at high pressure, and it was proved that water vapor dilution is effective to restrain CO emission, which is a possible defect of HiTAC when it is applied to Gas-turbine combustors.
