Heat Release Comparison Between Optical and All-Metal HSDI Diesel Engines

Aronsson, Ulf; Chartier, Clément; Horn, Uwe; Andersson, Öivind; Johansson, Bengt; Egnell, Rolf

doi:10.4271/2008-01-1062

Cited by 41 publications

(17 citation statements)

References 10 publications

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“…In order to avoid contact between the piston rings and the inner surface of the window cassettes, which are replaced by metal dummies for this experiment, the fire land height is increased. According to Aronsson et al 36 the resulting effect on combustion and in particular unburnt hydrocarbon (HC) emissions is weak for HSDI engines with combustion in the piston bowl and injection close to top dead center (TDC) of combustion.…”

Section: Engines and Operating Conditionsmentioning

confidence: 99%

“…The lack of piston cooling may lead to a higher glass-surface temperature in the optical engine at fired operation, as compared to the all-metal engine. 36,38,39 However, this effect is likely offset by the limited number of fired cycles of the optical engine. The in-cylinder average bulk-gas conditions at injection timing are given in Table 3 for both engines under the current operating conditions (without PD).…”

Section: Engines and Operating Conditionsmentioning

confidence: 99%

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Optical investigation of fuel and in-cylinder air-swirl effects in a high-speed direct-injection engine

Hülser

Jakob

Grünefeld

et al. 2014

International Journal of Engine Research

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The primary aim of this study is to investigate current issues of combustion in high-speed direct-injection diesel engines in detail by optical diagnostics. Both fuel and engine design are considered. Recently, measurements of engine-out emissions demonstrated that approximately soot-free combustion can be achieved using a newly designed two-component fuel named BLT. It was composed of 70% butyl levulinate and 30% n-tetradecane (by volume). In this work, the underlying mechanism is clarified by in-cylinder visualization of OH* radicals and soot. In particular, it turns out that in-cylinder soot formation is avoided almost completely, that is, the soot oxidation process is much less important. This is basically achieved by both the oxygen content (about 21%) and the low cetane number (approximately 33) of BLT. The latter leads to enhanced pre-mixing of fuel and air. Consequently, soot formation can be greatly reduced because it depends on the air-fuel ratio of the mixture shortly before high-temperature combustion. The influence of in-cylinder air swirl on combustion and soot formation is also studied for both BLT and conventional diesel fuel, respectively, using the same optical diagnostic. The measurements show that the combustion zone strongly depends on the local gas-flow velocity for diesel fuel. Soot formation decreases with increasing swirl because of enhanced air entrainment and pre-mixing of fuel and air. In addition, the results indicate that soot oxidation is improved under high-swirl conditions for diesel fuel. In contrast, the influence of swirl on the combustion of BLT is overall found to be weak, suggesting that swirl could be reduced in future high-speed direct-injection engines for BLT-like fuels.

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Section: Engines and Operating Conditionsmentioning

confidence: 99%

Section: Engines and Operating Conditionsmentioning

confidence: 99%

Optical investigation of fuel and in-cylinder air-swirl effects in a high-speed direct-injection engine

Hülser

Jakob

Grünefeld

et al. 2014

International Journal of Engine Research

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“…The TDC thermodynamic conditions on the optical engine were matched to those of the all-metal engine by adjusting the intake mass flow and composition, intake temperature and fueling rate. Aronsson et al [7] studied several optical engine configurations and compared experimental data with results obtained on a standard allmetal engine. The authors reported the effects of the material properties of optical components (windows) on the combustion process.…”

Section: Introductionmentioning

confidence: 99%

“…More recent studies [6,7] have been performed on highlighting the need to characterise the differences between optical and all-metal engines. Colban et al [5] performed a detailed study into the effects of EGR composition and in particular the use of simulated EGR on optical engines and the importance of including the major species such as N 2 , CO 2 , H 2 O, CO and UHC.…”

Section: Introductionmentioning

confidence: 99%

Optical Engines as Representative Tools in the Development of New Combustion Engine Concepts

Kashdan

Thirouard

2011

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Résumé -Moteurs transparents comme outils représentatifs dans le développement de nouveaux concepts des moteurs à combustion interne -Les moteurs monocylindres transparents sont employés comme outils de recherche et de développement des moteurs à combustion interne. Ils permettent l'utilisation de techniques de diagnostics non-intrusifs (qualitatifs et quantitatifs) pour étudier des phénomènes comme l'aérodynamique interne, la préparation du mélange, la combustion et la formation de polluants. Ces données expérimentales sont importantes pour la validation des modèles numériques et permettent également d'obtenir une compréhension détaillée des phénomènes physiques se déroulant dans la chambre. Les données recueillies aident au développement des nouvelles stratégies de combustion telles que la combustion homogène (HCCI) et la combustion Diesel à basse température (LTC). Dans ce contexte, il est important de s'assurer que le fonctionnement des moteurs transparents est tout à fait comparable et représentatif de celui des moteurs standards (opaques). Une comparaison du comportement de la combustion et des émissions des moteurs transparents et opaques a été réalisée. L'objectif était d'étudier les différences principales entre le moteur transparent et le moteur opaque et de comprendre comment ces différences peuvent influencer les phases de préparation du mélange, la combustion et la formation de polluants. Les résultats expérimentaux révèlent l'influence significative des différences liées à la température des parois de la chambre de combustion. Des mesures de la température des parois ont été effectuées par la technique de phosphorescence induite par laser. Ces mesures ont permis de définir des stratégies de fonctionnement moteur permettant de compenser les différences de température de paroi entre les deux moteurs. En outre, l'impact des différences géométriques des chambres a été investiguée. La réhausse piston peut subir soit un chargement mécanique dynamique (effets de compression ou de traction) soit une expansion thermique. Ces effets peuvent faire varier le taux de compression effectif. La charge admise dans les moteurs transparents est souvent diluée par de l'EGR simulé au lieu d'utiliser l'EGR réel. Dans les conditions de Diesel LTC, une comparaison a été effectuée entre l'utilisation d'EGR réel et d'EGR simulé par un gaz diluant pur. Enfin, les carburants mono-composants (carburants purs) sont souvent utilisés dans les moteurs Diesel transparents en raison des contraintes imposées par l'utilisation de techniques de diagnostics optiques. Cependant, les carburants purs diffèrent quelque peu des carburants Diesel réels, en particulier au travers de leur indice de cétane et de leur volatilité. Ces différences peuvent influencer fortement le comportement de la combustion et des émissions dans les moteurs transparents. Ces aspects ont été également traités dans cette étude. Une meilleure compréhension des différences de comportement entre les moteurs monocylindres transparents et moteurs standards (opaques) a pe...

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“…In addition, the optical liner had a greater clearance (i.e., a larger top ring-land volume, shown in Figure 2.5a) than the metal engine configuration, resulting in a greater blow-by [80]. These geometric differences, together with reduced heat transfer (lower thermal conductivity) [81], lowered the dynamic compression ratio to 11:1 in the optical configuration compared with the dynamic CR of 12.9:1 for the metal engine. Table 2.4 shows the optical engine Combustion chamber Flat bowl-in-piston and flat head specifications that are different from those of the metal engine in Table 2.1.…”

Section: Optical Engine Configurationmentioning

confidence: 99%

Investigation of Combustion Characteristics of a Heavy-Duty Diesel Engine Retrofitted to Natural Gas Spark Ignition Operation

Liu¹

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The conversion of existing diesel engines to natural-gas spark ignition operation by adding a gas injector in the intake manifold for fuel delivery and replacing the diesel fuel injector with a spark plug to initiate and control the combustion process can reduce U.S. dependence on petroleum imports and curtail engine-out emissions. As the conventional diesel combustion chamber (i.e., flat head and bowl-in-piston) creates high turbulence, the engine can operate leaner, which would increase its efficiency and reduce emissions. However, natural gas combustion in such retrofitted engines presents differences compared to that in conventional spark ignited engines. Subsequently, the main goal of this study was to investigate the characteristics of natural gas combustion inside a diesel-like, fast-burn combustion chamber using a unique array of experimental and numerical tools. The experimental platform consisted of a heavy-duty single-cylinder diesel engine converted to natural-gas spark ignition and operated at a low-speed, lean equivalence ratio, and medium-load condition. The engine can also operate in an optical configuration (i.e., the stock piston and cylinder block can be replaced with a see-through piston and an extended cylinder block), which was used to visualize flame behavior. The optical data indicated a thick and fast-propagated flame in the piston bowl but slower flame propagation inside the squish region. In addition, a 3D numerical model of the optical engine was built to better explain the geometry effects. The simulation results suggested that while the region around the spark plug location experienced a moderate turbulence that helped with the ignition process, the interaction of squish, piston motion, and intake swirl created a highly-turbulent environment that favored the fast burn inside the bowl and stabilized the combustion process. However, the squish region experienced a much lower turbulence, which, combined with the reduced temperature and pressure during the expansion stroke and its higher surface-to-volume ratio, reduced the burning velocity and the flame propagation, but also avoided knocking. Consequently, the bowl-in-piston geometry separated the leanburn natural gas combustion into two distinct events. To extend the optical findings, the metal engine configuration was used to investigate the effects of gas composition, spark timing, equivalence ratio, and engine speed on the two-stage combustion. The results suggested that operating conditions controlled the magnitude and phasing of the two combustion events. Moreover, 3D CFD simulations of the metal engine configuration showed that the squish region contained an important mixture fraction that would burn much slower and can increase the phasing separation between the two combustion events to a point that a second peak would appear in the heat release rate. Moreover, the rapidburn event in such an engine was much shorter compared to its traditional definition (i.e., the time in crank angle degrees between the 10% and 90% energy-releas...

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Heat Release Comparison Between Optical and All-Metal HSDI Diesel Engines

Cited by 41 publications

References 10 publications

Optical investigation of fuel and in-cylinder air-swirl effects in a high-speed direct-injection engine

Optical investigation of fuel and in-cylinder air-swirl effects in a high-speed direct-injection engine

Optical Engines as Representative Tools in the Development of New Combustion Engine Concepts

Investigation of Combustion Characteristics of a Heavy-Duty Diesel Engine Retrofitted to Natural Gas Spark Ignition Operation

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