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Turbocharger Matching Method for Reducing Residual Concentration in a Turbocharged Gasoline Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 14, 2015 by SAE International in United States
Annotation ability available
In a turbocharged engine, preserving the maximum amount of exhaust pulse energy for turbine operation will result in improved low end torque and engine transient response. However, the exhaust flow entering the turbine is highly unsteady, and the presence of the turbine as a restriction in the exhaust flow results in a higher pressure at the cylinder exhaust ports and consequently poor scavenging. This leads to an increase in the amount of residual gas in the combustion chamber, compared to the naturally-aspirated equivalent, thereby increasing the tendency for engine knock. If the level of residual gas can be reduced and controlled, it should enable the engine to operate at a higher compression ratio, improving its thermal efficiency.
This paper presents a method of turbocharger matching for reducing residual gas content in a turbocharged engine. The turbine is first scaled to a larger size as a preliminary step towards reducing back pressure and thus the residual gas concentration in-cylinder. However a larger turbine causes a torque deficit at low engine speeds. So in a following step, pulse separation is used. In optimal pulse separation, the gas exchange process in one cylinder is completely unimpeded by pressure pulses emanating from other cylinders, thereby preserving the exhaust pulse energy entering the turbine. A pulse-divided exhaust manifold enables this by isolating the manifold runners emanating from certain cylinder groups, even as far as the junction with the turbine housing.
This combination of appropriate turbine sizing and pulse-divided exhaust manifold design is applied to a Proton 1.6-litre CamPro CFE turbocharged gasoline engine model. The use of a pulse-divided exhaust manifold allows the turbine to be increased in size by 2.5 times (on a mass flow rate basis) while maintaining the same torque and power performance. As a consequence, lower back pressure and improved scavenging reduces the residual concentration by up to 43%, while the brake specific fuel consumption improves by approx. 1%, before any modification to the compression ratio is made.
CitationIsmail, M., Costall, A., Martinez-Botas, R., and Rajoo, S., "Turbocharger Matching Method for Reducing Residual Concentration in a Turbocharged Gasoline Engine," SAE Technical Paper 2015-01-1278, 2015, https://doi.org/10.4271/2015-01-1278.
- Smokers , R. , Vermeulen , R. , van Mieghem , R. , Gense , R. et al. Review and analysis of the reduction potential and costs of technological and other measures to reduce CO 2 -emissions from passenger cars Final Report, various organizations, Contract nr. SI2.408212 October 2006
- Hardcastle , J. Automotive Council Technology Work Groups Consensus Roadmaps and Workstream Feedback Low Carbon Vehicle Event September 2013
- Edwards , K. , Wagner , R. , Briggs , T. , and Theiss , T. Defining Engine Efficiency Limits Proc. 17th DEER Conference Detroit, USA October 2011
- Pagot , A. , Duparchy , A. , Gautrot , X. , Leduc , P. et al. Combustion Approach for Downsizing: the IFP Concept Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles 61 1 139 153 2006
- Watson , N. and Janota , M. S. Turbocharging the Internal Combustion Engine The Macmillan Press Ltd 1982
- Heywood , J.B. Internal Combustion Engine Fundamentals McGraw-Hill New York 1988
- Tancrez , M. , Galindo , J. , Guardiola , C. , Fajardo , P. et al. Turbine Adapted Maps for Turbocharger Engine Matching Experimental Thermal and Fluid Science 35 1 146 153 2011 10.1016/j.expthermflusci.2010.07.018
- Pohorelsky , L. , Brynych , P. , Macek , J. , Vallaude , P. et al. Air System Conception for a Downsized Two-Stroke Diesel Engine SAE Technical Paper 2012-01-0831 2012 10.4271/2012-01-0831
- Moraal , P. and Kolmanovsky , I. Turbocharger Modeling for Automotive Control Applications SAE Technical Paper 1999-01-0908 1999 10.4271/1999-01-0908
- Korakianitis , T. and Sadoi , T. Turbocharger-Design Effects on Gasoline-Engine Performance J. Eng. Gas Turbines Power 127 3 525 530 2005 10.1115/1.1808428
- Galliot , F. , Cheng , W. , Cheng , C. , Sztenderowicz , M. et al. In-Cylinder Measurements of Residual Gas Concentration in a Spark Ignition Engine SAE Technical Paper 900485 1990 10.4271/900485
- Fox , J. , Cheng , W. , and Heywood , J. A Model for Predicting Residual Gas Fraction in Spark-Ignition Engines SAE Technical Paper 931025 1993 10.4271/931025
- Westin , F. , Grandin , B. , and Ångström , H. The Influence of Residual Gases on Knock in Turbocharged SI-Engines SAE Technical Paper 2000-01-2840 2000 10.4271/2000-01-2840
- Möller , C. , Johansson , P. , Grandin , B. , and Lindström , F. Divided Exhaust Period - A Gas Exchange System for Turbocharged SI Engines SAE Technical Paper 2005-01-1150 2005 10.4271/2005-01-1150
- Gundmalm , S. Divided Exhaust Period on Heavy-Duty Diesel Engines Licentiate thesis Royal Institute of Technology Stockholm 2013
- Aghaali , H. and Angstrom , H.-E. The Exhaust Energy Utilization of a Turbocompound Engine Combined with Divided Exhaust Period Proc. IMechE Int. Conf. on Turbochargers and Turbocharging 179 188 2014
- Hu , B. , Brace , C. , Akehurst , S. , Copeland , C. et al. The Effect of Divided Exhaust Period for Improved Performance in a Highly Downsized Turbocharged Gasoline Engine Proc. IMechE Int. Conf. on Turbochargers and Turbocharging 27 39 2014
- Roth , D. , Keller , P. , and Sisson , J. Valve-Event Modulated Boost System SAE Technical Paper 2010-01-1222 2010 10.4271/2010-01-1222
- Roth , D. and Becker , M. Valve-Event Modulated Boost System: Fuel Consumption and Performance with Scavenge-Sourced EGR SAE Int. J. Engines 5 2 538 546 2012 10.4271/2012-01-0705
- Gamma-Technologies Inc. GT-SUITE Flow Theory Manual, V7.1 2010
- Woollenweber , W. The Turbocharger - A Vital Part of the Engine Intake and Exhaust Systems SAE Technical Paper 700534 1970 10.4271/700534
- Capobianco , M. and Polidori , F. Experimental Investigation on Open Waste-Gate Behaviour of Automotive Turbochargers SAE Technical Paper 2008-36-0052 2008 10.4271/2008-36-0052
- Marelli , S. , and Capobianco , M. Steady and Pulsating Flow Efficiency of a Waste-gated Turbocharger Radial Flow Turbine for Automotive Application Energy 36 1 459 465 2011 10.1016/j.energy.2010.10.019
- Wicke , V. , Brace , C. J. , Deacon , M. , and Vaughan , N. D. Preliminary Results from Driveability Investigations of Vehicles with Continuously Variable Transmissions Proceedings of CVT'99 Eindhoven University of Technology September 16-17 1999