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An experimental and modeling-based study into the ignition delay characteristics of diesel surrogate binary blend fuels / Matthew A. Carr in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 7 (Juillet 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 7 (Juillet 2012) . - 10 p. Titre : An experimental and modeling-based study into the ignition delay characteristics of diesel surrogate binary blend fuels Type de document : texte imprimé Auteurs : Matthew A. Carr, Auteur ; Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Ignition  delay  Combustion  characteristics  Diesel  fuels  Single-cylinder  research  engine  Homogeneous  reactor  model  Binary  blend  fuels Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study examines the combustion characteristics of a binary mixture surrogate for possible future diesel fuels using both a single-cylinder research engine and a homogeneous reactor model using detailed chemical reaction kinetics. Binary mixtures of a normal straight-chain alkane (pure n-hexadecane, also known as n-cetane, C16H34) and an alkyl aromatic (toluene, C7H8) were tested in a single-cylinder research engine. Pure n-hexadecane was tested as a baseline reference, followed by 50%, 70%, and 80% toluene in hexadecane blends. Testing was conducted at fixed engine speed and constant indicated load. As references, two conventional petroleum-based fuels (commercial diesel and U.S. Navy JP-5 jet fuel) and five synthetic Fischer-Tropsch-based fuels were also tested. The ignition delay of the binary mixture surrogate increased with increasing toluene fraction and ranged from approximately 1.3 ms (pure hexadecane) to 3.0 ms (80% toluene in hexadecane). While ignition delay changed substantially, the location of 50% mass fraction burned did not change as significantly due to a simultaneous change in the premixed combustion fraction. Detailed chemical reaction rate modeling using a constant pressure, adiabatic, homogeneous reactor model predicts a chemical ignition delay with a similar trend to the experimental results but shorter overall magnitude. The difference between this predicted homogeneous chemical ignition delay and the experimentally observed ignition delay is defined as the physical ignition delay due to processes such as spray formation, entrainment, mixing, and vaporization. On a relative basis, the addition of 70% toluene to hexadecane causes a nearly identical relative increase in both physical and chemical ignition delay of approximately 50%. The chemical kinetic model predicts that, even though the addition of toluene delays the global onset of ignition, the initial production of reactive precursors such as HO2 and H2O2 may be faster with toluene due to the weakly bound methyl group. However, this initial production is insufficient to lead to wide-scale chain branching and ignition. The model predicts that the straight-chain alkane component (hexadecane) ignites first, causing the aromatic component to be consumed shortly thereafter. Greater ignition delay observed with the high toluene fraction blends is due to consumption of OH radicals by toluene. Overall, the detailed kinetic model captures the experimentally observed trends well and may be able to provide insight as to the relationship between bulk properties and physical ignition delay. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000007 [...] [article] An experimental and modeling-based study into the ignition delay characteristics of diesel surrogate binary blend fuels [texte imprimé] / Matthew A. Carr, Auteur ; Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur . - 2012 . - 10 p. Génie mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 7 (Juillet 2012) . - 10 p. Mots-clés : Ignition  delay  Combustion  characteristics  Diesel  fuels  Single-cylinder  research  engine  Homogeneous  reactor  model  Binary  blend  fuels Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study examines the combustion characteristics of a binary mixture surrogate for possible future diesel fuels using both a single-cylinder research engine and a homogeneous reactor model using detailed chemical reaction kinetics. Binary mixtures of a normal straight-chain alkane (pure n-hexadecane, also known as n-cetane, C16H34) and an alkyl aromatic (toluene, C7H8) were tested in a single-cylinder research engine. Pure n-hexadecane was tested as a baseline reference, followed by 50%, 70%, and 80% toluene in hexadecane blends. Testing was conducted at fixed engine speed and constant indicated load. As references, two conventional petroleum-based fuels (commercial diesel and U.S. Navy JP-5 jet fuel) and five synthetic Fischer-Tropsch-based fuels were also tested. The ignition delay of the binary mixture surrogate increased with increasing toluene fraction and ranged from approximately 1.3 ms (pure hexadecane) to 3.0 ms (80% toluene in hexadecane). While ignition delay changed substantially, the location of 50% mass fraction burned did not change as significantly due to a simultaneous change in the premixed combustion fraction. Detailed chemical reaction rate modeling using a constant pressure, adiabatic, homogeneous reactor model predicts a chemical ignition delay with a similar trend to the experimental results but shorter overall magnitude. The difference between this predicted homogeneous chemical ignition delay and the experimentally observed ignition delay is defined as the physical ignition delay due to processes such as spray formation, entrainment, mixing, and vaporization. On a relative basis, the addition of 70% toluene to hexadecane causes a nearly identical relative increase in both physical and chemical ignition delay of approximately 50%. The chemical kinetic model predicts that, even though the addition of toluene delays the global onset of ignition, the initial production of reactive precursors such as HO2 and H2O2 may be faster with toluene due to the weakly bound methyl group. However, this initial production is insufficient to lead to wide-scale chain branching and ignition. The model predicts that the straight-chain alkane component (hexadecane) ignites first, causing the aromatic component to be consumed shortly thereafter. Greater ignition delay observed with the high toluene fraction blends is due to consumption of OH radicals by toluene. Overall, the detailed kinetic model captures the experimentally observed trends well and may be able to provide insight as to the relationship between bulk properties and physical ignition delay. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000007 [...]

Dynamic Modeling of Residual-Affected Homogeneous Charge Compression Ignition Engines with Variable Valve Actuation / Shaver, Gregory. M. in Transactions of the ASME . Journal of dynamic systems, measurement, and control, Vol. 127, N° 3 (Septembre 2005) 

Public ISBD [article]  in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 127, N° 3 (Septembre 2005) . - 374-381 p. Titre : Dynamic Modeling of Residual-Affected Homogeneous Charge Compression Ignition Engines with Variable Valve Actuation Titre original : Modèle Dynamique des Moteurs Homogènes Affectés d'Allumage Spontané de Charge de Résiduel avec la Mise en Action Variable de Valve Type de document : texte imprimé Auteurs : Shaver, Gregory. M., Auteur ; Edwards, Christopher F. ; Caton, Patrick A. ; Roelle, Matthew, J. ; Gerdes, J. Christian, Auteur Article en page(s) : 374-381 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Allumage  spontané  homogène  Moteur  à  combustion  Controleur  Cinétique  chimique  Masse  de  commande  Echappement  Propane Index. décimale : 620.1/389 Résumé : One practical method for achieving homogeneous charge compression ignition (HCCI) in internal combustion engines is to modulate the valve to trup or reinduct exhaust gases, increasing the energy of the charge, and enabling autoignition. Controlling combustion phacing with valve modulation can be challenging, however, since any controller must operate through the chemical kinetics of HCCI and account for the cycle to cycle dynamics arising from the retained exhaust gas. This paper presents a simple model of the overall HCCI process that captures these fondamental aspects. The model uses and integrated Arrhenius rate expression to capture the importance of species concentrations and temperature on the ignition process and predict the start of combustion. The cycle to cycle dynamics, in turn, develop through mass exchange between a control volume representing the cylinderand a control mass modeling the exhaust manifold. Despite its simplicity, the model predicts combustion phasing, pressure evolution and work output for propane combustion experiments at levels of fidelity comparable to more complex representations. Transient responses to valve timing changes are also captured and, with minor modification, the model can, in principle, be extended to handle a variety of fuels. Une méthode pratique pour réaliser l'allumage spontané homogène de charge (HCCI) dans des moteurs à combustion interne est de moduler la valve aux gaz d'échappement de trup ou de reinduct, augmentant l'énergie de la charge, et permettant l'auto-allumage. La combustion de contrôle phacing avec la modulation de valve peut être provocante, cependant, puisque n'importe quel contrôleur doit fonctionner par la cinétique chimique de HCCI et expliquer le cycle pour faire un cycle la dynamique résultant du gaz d'échappement maintenu. Cet article présente un modèle simple du processus global de HCCI qui capture ces aspects fondamental. Les utilisations de modèle et l'expression intégrée de taux d'Arrhenius de capturer l'importance des concentrations et de la température d'espèces sur le procédé d'allumage et de prévoir le début de la combustion. Le cycle pour faire un cycle la dynamique, à leur tour, se développent par l'échange de masse entre un volume de commande représentant le cylindre et une masse de commande modelant la tubulure d'échappement. En dépit de sa simplicité, le modèle prévoit la combustion mettant en phase, pressurise l'évolution et fonctionne le rendement pour des expériences de combustion de propane aux niveaux de la fidélité comparables à des représentations plus complexes. Des réponses passagères aux changements de synchronisation de valve sont également capturées et, avec la modification mineure, le modèle peut, en principe, être prolongé pour manipuler une variété de carburants. En ligne : greg.shaver@gmail.com, gerdes@stanford.edu, roelle@stanford.edu, caton@stanford. [...] [article] Dynamic Modeling of Residual-Affected Homogeneous Charge Compression Ignition Engines with Variable Valve Actuation = Modèle Dynamique des Moteurs Homogènes Affectés d'Allumage Spontané de Charge de Résiduel avec la Mise en Action Variable de Valve [texte imprimé] / Shaver, Gregory. M., Auteur ; Edwards, Christopher F. ; Caton, Patrick A. ; Roelle, Matthew, J. ; Gerdes, J. Christian, Auteur . - 374-381 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 127, N° 3 (Septembre 2005) . - 374-381 p. Mots-clés : Allumage  spontané  homogène  Moteur  à  combustion  Controleur  Cinétique  chimique  Masse  de  commande  Echappement  Propane Index. décimale : 620.1/389 Résumé : One practical method for achieving homogeneous charge compression ignition (HCCI) in internal combustion engines is to modulate the valve to trup or reinduct exhaust gases, increasing the energy of the charge, and enabling autoignition. Controlling combustion phacing with valve modulation can be challenging, however, since any controller must operate through the chemical kinetics of HCCI and account for the cycle to cycle dynamics arising from the retained exhaust gas. This paper presents a simple model of the overall HCCI process that captures these fondamental aspects. The model uses and integrated Arrhenius rate expression to capture the importance of species concentrations and temperature on the ignition process and predict the start of combustion. The cycle to cycle dynamics, in turn, develop through mass exchange between a control volume representing the cylinderand a control mass modeling the exhaust manifold. Despite its simplicity, the model predicts combustion phasing, pressure evolution and work output for propane combustion experiments at levels of fidelity comparable to more complex representations. Transient responses to valve timing changes are also captured and, with minor modification, the model can, in principle, be extended to handle a variety of fuels. Une méthode pratique pour réaliser l'allumage spontané homogène de charge (HCCI) dans des moteurs à combustion interne est de moduler la valve aux gaz d'échappement de trup ou de reinduct, augmentant l'énergie de la charge, et permettant l'auto-allumage. La combustion de contrôle phacing avec la modulation de valve peut être provocante, cependant, puisque n'importe quel contrôleur doit fonctionner par la cinétique chimique de HCCI et expliquer le cycle pour faire un cycle la dynamique résultant du gaz d'échappement maintenu. Cet article présente un modèle simple du processus global de HCCI qui capture ces aspects fondamental. Les utilisations de modèle et l'expression intégrée de taux d'Arrhenius de capturer l'importance des concentrations et de la température d'espèces sur le procédé d'allumage et de prévoir le début de la combustion. Le cycle pour faire un cycle la dynamique, à leur tour, se développent par l'échange de masse entre un volume de commande représentant le cylindre et une masse de commande modelant la tubulure d'échappement. En dépit de sa simplicité, le modèle prévoit la combustion mettant en phase, pressurise l'évolution et fonctionne le rendement pour des expériences de combustion de propane aux niveaux de la fidélité comparables à des représentations plus complexes. Des réponses passagères aux changements de synchronisation de valve sont également capturées et, avec la modification mineure, le modèle peut, en principe, être prolongé pour manipuler une variété de carburants. En ligne : greg.shaver@gmail.com, gerdes@stanford.edu, roelle@stanford.edu, caton@stanford. [...]

Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine / Caton, Patrick A. in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Titre : Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine Type de document : texte imprimé Auteurs : Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur ; Jim S. Cowart, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Diesel  engines  Ignition  Surface  tension  Viscosity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In order to better understand how future candidate diesel fuels may affect combustion characteristics in diesel engines, 21 pure component hydrocarbon fuels were tested in a single-cylinder diesel engine. These pure component fuels included normal alkanes (C6–C16), normal primary alkenes (C6–C18), isoalkanes, cycloalkanes/-enes, and aromatic species. In addition, seven fuel blends were tested, including commercial diesel fuel, U.S. Navy JP-5 aviation fuel, and five Fischer–Tropsch synthetic fuels. Ignition delay was used as a primary combustion metric for each fuel, and the ignition delay period was analyzed from the perspective of the physical delay period followed by the chemical delay period. While fuel properties could not strictly be varied independently of each other, several ignition delay correlations with respect to physical properties were suggested. In general, longer ignition delays were observed for component fuels with lower liquid fuel density, kinematic viscosity, and liquid-air surface tension. Longer ignition delay was also observed for component fuels with higher fuel volatility, as measured by boiling point and vapor pressure. Experimental data show two regimes of operation: For a carbon chain length of 12 or greater, there is little variation in ignition delay for the tested fuels. For shorter chain lengths, a fuel molecular structure is very important. Carbon chain length was used as a scaling variable with an empirical factor to collapse the ignition delay onto a single trend line. Companion detailed kinetic modeling was pursued on the lightest fuel species set (C6) since this fuel set possessed the greatest ignition delay differences. The kinetic model gives a chemical ignition delay time, which, together with the measured experimental ignition delay, suggests that the physical and chemical delay period have comparable importance. However, the calculated chemical delay periods capture the general variation in the overall ignition delay and could be used to predict the ignition delay of possible future synthetic diesel fuels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine [texte imprimé] / Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur ; Jim S. Cowart, Auteur . - 2012 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Mots-clés : Diesel  engines  Ignition  Surface  tension  Viscosity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In order to better understand how future candidate diesel fuels may affect combustion characteristics in diesel engines, 21 pure component hydrocarbon fuels were tested in a single-cylinder diesel engine. These pure component fuels included normal alkanes (C6–C16), normal primary alkenes (C6–C18), isoalkanes, cycloalkanes/-enes, and aromatic species. In addition, seven fuel blends were tested, including commercial diesel fuel, U.S. Navy JP-5 aviation fuel, and five Fischer–Tropsch synthetic fuels. Ignition delay was used as a primary combustion metric for each fuel, and the ignition delay period was analyzed from the perspective of the physical delay period followed by the chemical delay period. While fuel properties could not strictly be varied independently of each other, several ignition delay correlations with respect to physical properties were suggested. In general, longer ignition delays were observed for component fuels with lower liquid fuel density, kinematic viscosity, and liquid-air surface tension. Longer ignition delay was also observed for component fuels with higher fuel volatility, as measured by boiling point and vapor pressure. Experimental data show two regimes of operation: For a carbon chain length of 12 or greater, there is little variation in ignition delay for the tested fuels. For shorter chain lengths, a fuel molecular structure is very important. Carbon chain length was used as a scaling variable with an empirical factor to collapse the ignition delay onto a single trend line. Companion detailed kinetic modeling was pursued on the lightest fuel species set (C6) since this fuel set possessed the greatest ignition delay differences. The kinetic model gives a chemical ignition delay time, which, together with the measured experimental ignition delay, suggests that the physical and chemical delay period have comparable importance. However, the calculated chemical delay periods capture the general variation in the overall ignition delay and could be used to predict the ignition delay of possible future synthetic diesel fuels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]