This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Potential Benefits in Heavy Duty Diesel Engine Performance and Emissions from the Use of Variable Compression Ratio
Technical Paper
2006-01-0081
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Worldwide demand for reduction of automotive fuel consumption and carbon dioxide emissions results in the introduction of new diesel engine technologies. A promising technique for increasing the power density of reciprocating engines, improving fuel economy and curtailing engine exhaust emissions is the use of variable compression ratio (VCR) technology. Several automotive manufacturers have developed prototype vehicles equipped with VCR gasoline engines. The constructive pattern followed to alter the compression ratio varies with the manufacturer. The implementation of VCR technology offers two main advantages: the reduction of CO2 emissions due to optimal combustion efficiency in the entire range of engine operating conditions and the increase of power concentration due to high boosting of a small engine displacement (i.e., engine downsizing). However, the aforementioned benefits concern mainly spark ignition engines, where the increase of compression ratio during part-throttle operation results in a noticeable reduction of brake specific fuel consumption (bsfc) because of their thermodynamic operating cycle and the relatively low CR used. On the other hand, the application of VCR technology in heavy-duty diesel engine, if any, is extremely limited whereas is not expected to provide a similar benefit since their compression ratio is already higher than spark-ignition engines. In addition, high values of compression ratio are necessary in diesel engines to ensure proper auto-ignition of injected diesel fuel. The variation of compression ratio in heavy-duty diesel engines confronts with the excessive increase of peak combustion pressure (Pmax) mainly at high engine loads. Specifically, studies conducted in the past by the present research group dealing with the application of “internal measures” in diesel engines, revealed the possibility for reducing bsfc and NOx emissions without significant penalty on soot using advanced injection timing and high EGR rates. However, this resulted in a considerable increase of peak combustion pressure, which generates serious structural problems at high engine load. Therefore, the use of a variable compression ratio in heavy-duty diesel engines can be a promising technique to control peak combustion pressure. In this case, a high compression ratio can be maintained at part load while a lower one can be used at full load where peak firing pressure is a problem. However, it is still doubtful if the expected improvement in fuel economy will be overwhelmed by the manufacturing complexity and the subsequent cost aggravation and reliability implications, which will accompany the application of this technology in diesel engines. For this reason, in the present study, an engine simulation model is used to investigate potential benefits in specific fuel consumption of a heavy duty DI diesel engine by varying its compression ratio. Additionally, the implications on engine exhaust emissions and peak combustion pressure from the implementation of VCR technology at both part and full load conditions are examined. The main objective of the study is to identify the necessary variation of compression ratio with engine operating conditions to achieve optimum fuel consumption, avoid excessive peak combustion pressures, and assess its repercussions on engine out emissions with regard to future emission standards. This analysis will facilitate the determination of a possible “optimized” variation law of compression ratio with engine speed and load for heavy-duty diesel engines. The results of this theoretical examination in conjunction with serious technical issues accompanying the variation of compression ratio will judge the applicability of this technique in heavy-duty diesel engines.
Recommended Content
Authors
Topic
Citation
Hountalas, D., Zannis, T., and Mavropoulos, G., "Potential Benefits in Heavy Duty Diesel Engine Performance and Emissions from the Use of Variable Compression Ratio," SAE Technical Paper 2006-01-0081, 2006, https://doi.org/10.4271/2006-01-0081.Also In
References
- Grebe U-D. Imarisio R. “Gasoline or diesel engine: the race is on!” FISITA World Automotive Congress Barcelona, Spain Paper No F2004V097 2004
- Binder K. Schwarz V. “Present and future of heavy duty engine strategies for compliance to the emission legislation” Conf. on Thermo- and Fluid Dynamic Processes in Diesel Engines (THIESEL) Valencia, Spain 2002
- Hountalas D.T. Mavropoulos G.C. Zannis T.C. Schwarz V. “Possibilities to achieve future emission limits for HD DI diesel engines using internal measures” SAE Paper No 2005-01-0377 2005
- Hountalas D.T. “Controlling nitric oxide and soot in heavy duty diesel engines using internal measures” FISITA World Automotive Congress Barcelona, Spain Paper No F2004V262 2004
- Hountalas D.T. Kouremenos D.A. Mavropoulos G.C. Binder K.B. Schwarz V. “Multi-zone combustion modeling as a tool for DI diesel engine development - Application for the effect of injection pressure” SAE Paper No 2004-01-0115 2004
- Hountalas D.T. Kouremenos D.A. Binder K.B. Raab A. Schnabel M.H. “Using advanced injection timing and EGR to improve DI diesel engine efficiency at acceptable NO and soot levels” SAE Paper No 2001-01-0199 2001
- Payri F. Benajes J. Molina S. Riesco J.M. “Reduction of pollutant emissions in a HD diesel engine by adjustment of injection parameters, boost pressure and EGR” SAE Paper No 2003-01-0343 2003
- Abou Al-Sood M.M. Abdel-Latif A.A. Abdel-Rahim Y.M. Ibrahim A.M. “Optimum compression ratio variation of a 4-stroke, direct injection diesel engine for minimum bsfc” SAE Paper No 1999-01-2519 1999
- Abou Al-Sood M.M. Abdel-Latif A.A. Abdel-Rahim Y.M. Ibrahim A.M. “Optimum compression ratio variation of a 4-stroke, direct injection diesel engine for maximum brake power and torque and minimum soot and NOx emissions” SAE Paper No 1999-01-2728 1999
- “PLN-based improved combustion for low emissions (PICE)” GROWTH, G3RD-CT-2000-00283 2004
- Drangel H. Olofsson E. Reinmann R. “The variable compression (SVC) and the combustion control (SCC) - Two ways to improve fuel economy and still comply with world-wide emission requirements” SAE Paper No 2002-01-0996 2002
- Schwaderlapp M. Habermann K. Yapici K.I. “Variable compression ratio - A design solution for fuel economy concepts” SAE Paper No 2002-01-1103 2002
- Mendler C. Gravel R. “Variable compression ratio engine” SAE Paper No 2002-01-1940 2002
- Roberts M. “Benefits and challenges of variable compression ratio (VCR)” SAE Paper No 2003-01-0398 2003
- Moteki K. Aoyama S. Ushijima K. Hiyoshi R. Takemura S. Fujimoto H. Arai T. “A study of variable compression ratio system with a multi-link mechanism” SAE Paper No 2003-01-0921 2003
- Rabhi V. Beroff J. Dionnet F. “Study of a gear-based variable compression ratio engine” SAE Paper No 2004-01-2931 2004
- Takahashi N. Aoyama S. Moteki K. Hiyoshi R. “A study concerning the noise and vibration characteristics of an engine with multiple-link variable compression ratio mechanism” SAE Paper No 2005-01-1134 2005
- Ladommatos N. Balian R.A. “Combustion in a direct injection diesel engine with increased clearance volume” Proc. Instn Mech Engrs 204 D01690 187 197 1990
- Rychter T.J. Teodorczyk A. Stone C.R. Leonard H.J. Ladommatos N. Charlton S.J. “A theoretical study of a variable compression ratio turbocharged diesel engine” Proc Instn Mech Engrs 227 238 1992
- Sobotowski R.A. Porter B.C. Pilley A.D. “The development of a novel variable compression ratio, direct injection diesel engine” SAE Paper No 910484
- Jung A. Assanis D.N. “Multi-zone DI diesel spray combustion model for cycle simulation studies on engine performance and emissions” SAE Paper No 2001-01-1246 2001
- Launder B.E. Spalding D.B. Mathematical Models of Turbulence Academic Press London & NY 1972
- Annand W.J.D. “Heat transfer in the cylinders of reciprocating internal combustion engines” Proc. Instn Mech Engrs 177 973 990 1963
- Heywood J.B. Internal Combustion Engine Fundamentals McGraw-Hill NY 1988
- Dent J.C. Derham J.A. “Air motion in a four-stroke direct injection diesel engine” Proc. Instn Mech. Engrs 188 269 280 1974
- Ramos J.I. Internal Combustion Engine Modelling Hemisphere, New York 1989
- Borman G.L. Johnson J.H. “Unsteady vaporization histories and trajectories of fuel drops injected into swirling air” SAE Paper No. 598C , National Powerplant Meeting Philadelphia PA 1962
- Kadota T. Hiroyasu H. Oya H. “Spontaneous ignition delay of a fuel droplet in high pressure and high temperature gaseous environments” Bulletin JSME 19 130 1976
- Lavoie G.A. Heywood J.B. Keck J.C. “Experimental and theoretical study of nitric oxide formation in internal combustion engines” Combust Sci and Technol 1 313 326 1970
- Nishida K. Hiroyasu H. “Simplified three-dimensional modelling of mixture formation and combustion in a D.I. diesel engine” SAE Paper No 890269 1989