DE3-1: Evaluation of Pilot Injections in a Large Two-Stroke Marine Diesel Engine, Using CFD and T-φ Mapping(DE: Diesel Engine Combustion,General Session Papers) (original) (raw)
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In 2002 the European Commission adopted a European Union strategy to reduce atmospheric emissions from seagoing ships. The strategy reports on the magnitude and impact of ship emissions in the EU, and sets out a number of actions to reduce the contribution of shipping to health and climate change. One possible approach for the reduction of NO X and soot emissions of marine diesel engines is the use of multiple injection strategies, similar to the ones used in automotive diesel engines. In this way, diesel combustion could be optimized with respect to pollutant emissions, without compromising fuel efficiency.
In 2002 the European Commission adopted a European Union strategy to reduce atmospheric emissions from seagoing ships. The strategy reports on the magnitude and impact of ship emissions in the EU, and sets out a number of actions to reduce the contribution of shipping to health and climate change. One possible approach for the reduction of NO X and soot emissions of marine diesel engines is the use of multiple injection strategies, similar to the ones used in automotive diesel engines. In this way, diesel combustion could be optimized with respect to pollutant emissions, without compromising fuel efficiency. Our interest is in investigating the potential for emissions reduction and overall optimization of combustion in large two-stroke marine diesel engines, using numerical simulation. In this context, we study the effects of advanced injection strategies by utilizing Computational Fluid Dynamics (CFD) tools. We use the KIVA-3 code as the modeling platform, with improved models for spray breakup, autoignition and combustion. Here, we report first results, corresponding to pilot injections, which are visualized for the fuel injection and combustion processes, and are also mapped on temperature-equivalence ratio charts (T-φ maps). This analysis reveals important information on pollutant formation mechanisms in large marine diesel engines.
Evaluation of Pilot Injections in a Large Two-Stroke Marine Diesel Engine, Using CFD and T-φ Mapping
In 2002 the European Commission adopted a European Union strategy to reduce atmospheric emissions from seagoing ships. The strategy reports on the magnitude and impact of ship emissions in the EU, and sets out a number of actions to reduce the contribution of shipping to health and climate change. One possible approach for the reduction of NO X and soot emissions of marine diesel engines is the use of multiple injection strategies, similar to the ones used in automotive diesel engines. In this way, diesel combustion could be optimized with respect to pollutant emissions, without compromising fuel efficiency.
Computational Fluid Dynamics (CFD) study of compression ignition (CI) engines provides invaluable insights into in-cylinder conditions and processes, which greatly expands on the very limited detail provided by engine output measurements, fuel consumption measurements, and engine-out measurements of exhaust emissions. CFD modeling and simulation has therefore become an attractive alternative for engine analysis in place of full experimental testbed study in recent years. In this research work, the performance of a single cylinder four stroke diesel engine was investigated. Commercial simulation software ANSYS Forte was used to study the combustion and emission characteristics of a diesel engine, in order to establish strategies for improvement of in-cylinder combustion and emission control. Normal heptane (n-heptane) was used as the surrogate fuel to represent diesel. Simulation results are compared against data from experimental testbed studies in terms of in-cylinder pressure profiles, heat release rate and exhaust emission of oxides of nitrogen (NO x), soot and unburned hydrocarbon (UHC) levels. The pressure trace from the simulations is found to be within a reasonable error limit of 10%. The combustion process is simulated with special focus on exhaust emissions of soot, NO x and unburned hydrocarbon. Graphical plots for mass fraction of soot, NO x and UHC are presented and discussed to elucidate the formation of these emissions. Graphics contours of temperature, NO mass fraction and oxygen concentration within the combustion chamber are also presented and discussed. The effects of injection timing on engine in-cylinder pressure, heat release rate and exhaust emissions are also studied by varying the injection timing and maintaining constant injection duration. Results are compared for the three different injection timings investigated, namely start of injection (SOI) 18 o bTDC, 15 o bTDC and 12 o bTDC. Emissions of soot and NO x are found to decrease with retarded injection timing. However, the peak in-cylinder pressure is greatly reduced and hence the output power is low. Injection timing is found to have no significant effect on emissions of UHC. The optimum injection timing that gives high output power and relatively low emission is 15 o bTDC. Downloaded From: http://proceedings.asmedigitalcollection.asme.org/ on 08/31/2017 Terms of Use: http://www.asme.org/about-asme/terms-of-use
International Journal of Energy Research, 2003
A two-zone model for the calculation of the closed cycle of a direct injection (DI) diesel engine is presented. The cylinder contents are taken to comprise a non-burning zone of air and another homogeneous zone in which fuel is continuously supplied from the injector holes during injection and burned with entrained air from the air zone. The growth of the fuel spray zone, consisting of a number of fuel-air conical jets equal to the injector nozzle holes, is carefully modelled by incorporating jet mixing to determine the amount of oxygen available for combustion. Application of the mass, energy and state equations in each one of the two zones yields local temperatures and cylinder pressure histories. For calculating the concentration of constituents in the exhaust gases, a chemical equilibrium scheme is adopted for the C-H-O system of the 11 species considered, together with chemical rate equations for the calculation of nitric oxide (NO). A model for the evaluation of soot formation and oxidation rates is incorporated. A comparison is made between the theoretical results from the computer program implementing the analysis, with experimental results from a vast experimental investigation conducted on a fully automated test bed, direct injection, standard 'Hydra', diesel engine located at the authors' laboratory, with very good results, following a multiparametric study of the constants incorporated in the various sub-models. Pressure indicator diagrams and plots of temperature, NO, soot density and of other interesting quantities are presented as a function of crank angle, for various loads and injection timings, elucidating the physical mechanisms governing combustion and pollutants formation.
Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 2008
-Modélisation 0D des émissions polluantes Diesel : développement et utilisation d'une méthodologie de couplage entre un modèle de combustion Diesel 0D et un modèle de polluants-Afin de satisfaire les normes de pollution de plus en plus sévères, les constructeurs automobiles ont généralisé l'utilisation du contrôle électronique du moteur. Ce contrôle permet de s'assurer en permanence du fonctionnement optimum du moteur en adéquation avec la demande de couple du conducteur et le bon fonctionnement des organes de post-traitement. Le développement et la calibration des algorithmes de contrôle moteur ne peuvent se faire qu'avec une compréhension fine du comportement dynamique du groupe motopropulseur, couplé à sa ligne d'échappement. Jusqu'à présent, un grand nombre d'essais sur banc moteur et sur véhicule était nécessaire pour atteindre des niveaux de calibration suffisants pour le contrôleur. Afin de diminuer les coûts de production, il devient de plus en plus important de limiter ces essais expérimentaux en ayant recours à la simulation. Dans ce contexte, il est important de disposer de modèles de combustion et de polluants prédictifs, calibrés sur un nombre limité de points expérimentaux et utilisables sur une grande plage de points de fonctionnement moteur. Ce papier présente un modèle 0D de combustion Diesel, basé sur le modèle de Barba [Barba C. et al. (2000)-A Phenomenological Combustion Model for Heat Release Rate Prediction in High Speed DI Diesel Engines with Common Rail Injection, SAE Technical Paper 2000-01-2933], permettant en particulier de prendre en compte l'impact de la multi-injection sur le déroulement de la combustion. Le modèle répartit chaque injection en deux zones : une première pour la flamme de pré-mélange lors du début de la combustion et une autre pour la flamme de diffusion. Afin de simuler la production de polluants, un modèle de mélange indexé sur l'énergie cinétique turbulente générée par le spray a été introduit. Ce dernier modèle permet de créer une zone de gaz brûlés dans la chambre de combustion dans laquelle les émissions de CO, NO x et suies sont calculées. Les modèles de polluants sont d'abord validés en utilisant le logiciel CHEMKIN et des résultats de calculs 3D. Des résultats expérimentaux obtenus sur un moteur 4 cylindres Diesel à injection directe en fonctionnement stabilisé sont ensuite utilisés pour valider et calibrer le couplage entre le modèle de combustion et les modèles de polluants. Le simulateur ainsi calibré est enfin utilisé pour simuler un fonctionnement en transitoire de charge du moteur.
International Journal of Engine Research, 2017
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SAE Technical Paper Series, 2004
This work is a part of an extended investigation conducted by the authors to validate and improve a newly developed quasi-dimensional combustion model. The model has been initially applied on an old technology, naturally aspirated HSDI Diesel engine and the results were satisfying as far as performance and pollutant emissions (Soot and NO) are concerned. But since obviously further and more extended validation is required, in the present study the model is applied on a new technology, heavy-duty turbocharged DI Diesel engine equipped with a high pressure PLN fuel injection system. The main feature of the model is that it describes the air-fuel mixing mechanism in a more fundamental way compared to existing multi-zone phenomenological combustion models, while being less time consuming and complicated compared to the more accurate CFD models. The finite volume method is used to solve the conservation equations of mass, energy and species concentration. The gas flow field is estimated using a newly developed semi-empirical gas motion model based on the assumption that in-cylinder pressure is uniform. Spray trajectory, fuel vaporization and combustion are simulated using simplified sub-models based on semi-empirical correlations. From this investigation, comparing the calculated with experimental results, it is revealed that the model manages to describe the effect of operating conditions on pollutant emissions (Soot and NO) at least qualitatively and provide a good estimation of the mean cylinder pressure diagram. Moreover the estimation of in-cylinder distribution of temperature, equivalence ratio and pollutants emissions concentrations (Soot and NO), seems to be reliable and in accordance with the conceptual model of diesel combustion. This is encouraging since the model can describe the fuel-air mixing and combustion mechanism, in two different Diesel Engine designs, without modification.
2016
I would also like to thank Prof. André L. Boehman and Professor Panos Y. Papalambros for serving on my dissertation committee and providing me with your invaluable feedback, as well as Professor Kazuhiro Saitou for serving as a surrogate committee member at the thesis defense. In addition, I would like to thank Prof. Peter Adriaens for serving as the cognate of my dissertation committee and providing a unique perspective from your fields of expertise by tirelessly challenging me to see the bigger picture and the greater impact of my work. Having completed 165 graded credit hours at the University of Michigan between undergraduate and graduate classes, I owe a big thank you to each and every one of my university professors that have contributed to my fundamental academic knowledge that I will carry with me for the rest of my life. I would like to express my sincere gratitude to my research sponsors including the Department of Energy, Hyundai-America Technical Center, Inc., Delphi, and the Department of Mechanical Engineering. Without your monetary and intellectual support, this entire project would have not been possible. To my friends, my past lab-mates, and my present lab-mates, this has been one fun and adventurous ride. I will always treasure the memories, friendships, discussions, and experiences we have shared together. We may be geographically separated in the future, but we will never be strangers. The bonds we have formed cannot be broken. Last, but not least I would like to thank my family. My four-legged fuzzy friend, Atlas, who has served as my most loyal and trusted companion through the toughest of times, always greeting me at the door with the biggest of smiles and happiest of