Documents disponibles écrits par cet auteur

Model-based control of HCCI engines using exhaust recompression / Nikhil Ravi in IEEE Transactions on control systems technology, Vol. 18 N° 6 (Novembre 2010) 

Public ISBD [article]  in IEEE Transactions on control systems technology > Vol. 18 N° 6 (Novembre 2010) . - pp. 1289-1302 Titre : Model-based control of HCCI engines using exhaust recompression Type de document : texte imprimé Auteurs : Nikhil Ravi, Auteur ; Roelle, Matthew, J., Auteur ; Hsien-Hsin Liao, Auteur Année de publication : 2011 Article en page(s) : pp. 1289-1302 Note générale : Energie Aéronospatial Langues : Anglais (eng) Mots-clés : Cycle-by-cycle  control  Cyclic  variability  Homogeneous  charge  compression  ignition  (HCCI)  Physical  modeling  Linear  control Index. décimale : 629.1 Résumé : Homogeneous charge compression ignition (HCCI) is one of the most promising piston-engine concepts for the future, providing significantly improved efficiency and emissions characteristics relative to current technologies. This paper presents a framework for controlling an HCCI engine with exhaust recompression and direct injection of fuel into the cylinder. A physical model is used to describe the HCCI process, with the model states being closely linked to the thermodynamic state of the cylinder constituents. Separability between the effects of the control inputs on the desired outputs provides an opportunity to develop a simple linear control scheme, where the fuel is used to control the work output and the valve timings are used to control the phasing of combustion. The controller is tested on both a single and multi-cylinder HCCI engine, demonstrating the value of a physical model-based control approach that allows an easy porting of the control structure from one engine to another. Experimental results show good tracking of both the work output and combustion phasing over a wide operating region on both engines. In addition, the controller is able to balance out differences between cylinders on the multi-cylinder engine testbed, and reduce the cycle-to-cycle variability of combustion. DEWEY : 629.1 ISSN : 1063-6536 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5356220 [article] Model-based control of HCCI engines using exhaust recompression [texte imprimé] / Nikhil Ravi, Auteur ; Roelle, Matthew, J., Auteur ; Hsien-Hsin Liao, Auteur . - 2011 . - pp. 1289-1302. Energie Aéronospatial Langues : Anglais (eng) in IEEE Transactions on control systems technology > Vol. 18 N° 6 (Novembre 2010) . - pp. 1289-1302 Mots-clés : Cycle-by-cycle  control  Cyclic  variability  Homogeneous  charge  compression  ignition  (HCCI)  Physical  modeling  Linear  control Index. décimale : 629.1 Résumé : Homogeneous charge compression ignition (HCCI) is one of the most promising piston-engine concepts for the future, providing significantly improved efficiency and emissions characteristics relative to current technologies. This paper presents a framework for controlling an HCCI engine with exhaust recompression and direct injection of fuel into the cylinder. A physical model is used to describe the HCCI process, with the model states being closely linked to the thermodynamic state of the cylinder constituents. Separability between the effects of the control inputs on the desired outputs provides an opportunity to develop a simple linear control scheme, where the fuel is used to control the work output and the valve timings are used to control the phasing of combustion. The controller is tested on both a single and multi-cylinder HCCI engine, demonstrating the value of a physical model-based control approach that allows an easy porting of the control structure from one engine to another. Experimental results show good tracking of both the work output and combustion phasing over a wide operating region on both engines. In addition, the controller is able to balance out differences between cylinders on the multi-cylinder engine testbed, and reduce the cycle-to-cycle variability of combustion. DEWEY : 629.1 ISSN : 1063-6536 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5356220

Modeling and control of an exhaust recompression HCCI engine using split injection / Nikhil Ravi in Transactions of the ASME . Journal of dynamic systems, measurement, and control, Vol. 134 N° 1 (Janvier 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 134 N° 1 (Janvier 2012) . - 12 p. Titre : Modeling and control of an exhaust recompression HCCI engine using split injection Type de document : texte imprimé Auteurs : Nikhil Ravi, Auteur ; Hsien-Hsin Liao, Auteur ; Adam F. Jungkunz, Auteur Année de publication : 2012 Article en page(s) : 12 p. Note générale : Dynamic systems Langues : Anglais (eng) Mots-clés : Combustion  Exhaust  systems  Fuel  systems  Intake  systems  (machines)  Internal  combustion  engines  Thermodynamics  Valves Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : Homogeneous charge compression ignition (HCCI) is currently being pursued as a cleaner and more efficient alternative to conventional engine strategies. Control of the load and phasing of combustion is critical in the effort to ensure reliable operation of an HCCI engine over a wide operating range. This paper presents an approach for modeling the effect of a small pilot injection during the recompression process of an HCCI engine, and a controller that uses the timing of this pilot injection to control the phasing of combustion. The model is a nonlinear physical model that captures the effect of fuel quantity and intake and exhaust valve timings on work output and combustion phasing. It is seen that around the operating points considered, the effect of a pilot injection can be modeled as a change in the Arrhenius threshold, an analytical construct used to model the phasing of combustion as a function of the thermodynamic state of the reactant mixture. The relationship between injection timing and combustion phasing can be separated into a linear, analytical component and a nonlinear, empirical component. Two different control strategies based on this model are presented, both of which enabled steady operation at low load conditions and effectively track desired load-phasing trajectories. These strategies demonstrate the potential of split injection as a practical cycle-by-cycle control knob requiring only minimal valve motion that would be easily achievable on current production engines equipped with cam phasers. DEWEY : 553 ISSN : 0022-0434 En ligne : http://www.asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JDSMAA00013400 [...] [article] Modeling and control of an exhaust recompression HCCI engine using split injection [texte imprimé] / Nikhil Ravi, Auteur ; Hsien-Hsin Liao, Auteur ; Adam F. Jungkunz, Auteur . - 2012 . - 12 p. Dynamic systems Langues : Anglais (eng) in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 134 N° 1 (Janvier 2012) . - 12 p. Mots-clés : Combustion  Exhaust  systems  Fuel  systems  Intake  systems  (machines)  Internal  combustion  engines  Thermodynamics  Valves Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : Homogeneous charge compression ignition (HCCI) is currently being pursued as a cleaner and more efficient alternative to conventional engine strategies. Control of the load and phasing of combustion is critical in the effort to ensure reliable operation of an HCCI engine over a wide operating range. This paper presents an approach for modeling the effect of a small pilot injection during the recompression process of an HCCI engine, and a controller that uses the timing of this pilot injection to control the phasing of combustion. The model is a nonlinear physical model that captures the effect of fuel quantity and intake and exhaust valve timings on work output and combustion phasing. It is seen that around the operating points considered, the effect of a pilot injection can be modeled as a change in the Arrhenius threshold, an analytical construct used to model the phasing of combustion as a function of the thermodynamic state of the reactant mixture. The relationship between injection timing and combustion phasing can be separated into a linear, analytical component and a nonlinear, empirical component. Two different control strategies based on this model are presented, both of which enabled steady operation at low load conditions and effectively track desired load-phasing trajectories. These strategies demonstrate the potential of split injection as a practical cycle-by-cycle control knob requiring only minimal valve motion that would be easily achievable on current production engines equipped with cam phasers. DEWEY : 553 ISSN : 0022-0434 En ligne : http://www.asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JDSMAA00013400 [...]