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Some Observations on the Effects of EGR, Oxygen Concentration, and Engine Speed on the Homogeneous Charge Combustion of n-Heptane
Technical Paper
2004-01-1905
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
NOx and soot emissions remain critical issues in diesel engines. One method to address these problems is to achieve homogeneous combustion at lower peak temperatures - the goal of research on controlled autoignition. In this paper n-heptane is used to represent a large hydrocarbon fuel and some of the effects of internal and external EGR, oxygen concentration, and engine speed on its combustion have been examined through simulation and experiment. Simulations were conducted using our existing skeletal chemical kinetic model, which combines the chemistry of the low, intermediate, and high temperature regimes. Experiments were carried out in a single cylinder, four-stroke, air cooled engine and a single cylinder, two stroke, water cooled engine.
In the four-stroke engine experiments the effects of EGR were examined using heated N2 addition as a surrogate for external EGR and engine modifications to increase internal EGR. Two-stage ignition was observed in both the simulations and experiments. The modeling results indicate that the ignition times were sensitive to EGR through both thermal and chemical effects. High levels of EGR completely suppressed autoignition. The most apparent effect of oxygen concentration is a shortening of the time between the first stage and second stage ignition. The modeling shows that EGR or extra air are key factors in eliminating knock during mid-load conditions. For higher load operation knock is serious and the only way to avoid it is to control reaction timing through the use of spark ignition. The experimental and modeling results from the two-stroke engine show that autoignition can be avoided by increasing the engine speed. This appears to result from shortened reaction time at lower temperatures thereby reducing the extent of the low and intermediate temperature chemical reactivity. The two-stroke engine experiments indicate that high levels of internal EGR (obtained by increasing the engine back pressure) can enable spark ignition at lean/dilute conditions. Based on the similarity between two-stoke and four-stroke engines, spark ignition may be possible at higher load conditions using internal EGR (simultaneously keeping peak temperature lower) for four-stroke engines.
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Authors
- Jincai Zheng - Mechanical Engineering Department, Drexel University
- David L. Miller - Mechanical Engineering Department, Drexel University
- Nicholas P. Cernansky - Mechanical Engineering Department, Drexel University
- Dexin Liu - National Engine Combustion Laboratory, Tianjin University
- Xinshun Zhao - National Engine Combustion Laboratory, Tianjin University
- Mingxian Zhang - College of Chemical Engineering, Beijing Union University
Topic
Citation
Zheng, J., Miller, D., Cernansky, N., Liu, D. et al., "Some Observations on the Effects of EGR, Oxygen Concentration, and Engine Speed on the Homogeneous Charge Combustion of n-Heptane," SAE Technical Paper 2004-01-1905, 2004, https://doi.org/10.4271/2004-01-1905.Also In
References
- Onishi, S. Hong, J.S. Shoda, K. Do, J.P. Kato, S. 1979 “Active Thermo-Atmosphere Combustion (ATAC) - A New Combustion Process for Internal Combustion Engine” SAE Paper No. 790501
- Noguchi, M. Tanaka, Y. Tanaka, T. Takeuchi, Y. 1979 “A Study on Gasoline Engine Combustion by Observation of Intermediate Reactive Products during Combustion,” SAE Paper No. 790840
- Najt, P.M. Foster, D.E. 1983 “Compression-Ignited Homogeneous Charge Combustion,” SAE Paper No. 83064
- Thring, R.H. 1989 “Homogeneous Charge Compression Ignition (HCCI) Engines,” SAE Paper No. 892068
- Ryan T.W. III Callahan, T.J. 1996 “Homogeneous Charge Compression Ignition of Diesel Fuel,” SAE Paper No. 961160
- Christensen, M. Johansson, B. Einewall, P. 1997 “Homogeneous Charge Compression Ignition (HCCI) Using Isooctane, Ethanol and Natural Gas - a Comparison with Spark Ignition Operation,” SAE Paper No. 972874
- Christensen, M. Johansson, B. Amnjus, P. Mauss, F. 1998 “Supercharged Homogeneous Charge Compression Ignition,” SAE Paper No. 980787
- Sheppard, C.G.W. Tolegano, S. Woolley, R. 2002 “On the Nature of Autoignition Leading to Knock in HCCI Engines,” SAE Paper No. 2002-01-2831
- Yang, J. Culp, T. Kenney, T. 2002 “Development of a Gasoline Engine System Using HCCI Technology - The Concept and the Test Results,” SAE Paper No. 2002-01-2832
- Simescu, S. Fiveland. S.B. Dodge, L.G. 2003 “An Experimental Investigation of PCCI-DI Combustion and Emissions in a Heavy-Duty Diesel Engine,” SAE Paper No. 2003-01-0345
- Allen, J. Law D 2002 “Variable Valve Actuated Controlled Auto-Ignition: Speed Load Maps and Strategic Regimes of Operation,” SAE Paper No. 2002-01-0422
- Walter, B. Gatellier, B 2002 “Development of the High Power NADI™ Concept Using Dual Mode Diesel Combustion to Achieve Zero NOx and Particulate Emissions,” SAE Paper No. 2002-01-1744
- Christensen, M. Hultqvist, A. Johansson, B. 1999 “Demonstrating the Multi Fuel Capability of a Homogeneous Charge Compression Ignition Engine with Variable Compression Ratio,” SAE Paper No. 1999-01-3679
- Peng, Z. Zhao, H. Ladommatos, N. 2003 “Effect of Air/Fuel Ratios and EGR Rates on HCCI Combustion of n-Heptane, a Diesel Type Fuel,” SAE Paper No. 2003-01-0747
- Akagawa, H. Miyamoto, T. Harada, A. Sasaki, S. Shimazaki, N. Hashizume, T. Tsujimura, K. 1999 “Approaches to Solve Problems of the Premixed Lean Diesel Combustion,” SAE Paper No. 1999-01-0183
- Kimura, S. Aoki, O. Ogawa, H. Muranaka, S. 1999 “New Combustion for Ultra-Clean and High-Efficiency Small DI Diesel Engines,” SAE Paper No. 1999-01-3681
- Kaneko, N. Ando, H. Ogawa, H. Miyamoto. N. 2002 “Expansion of the Operation Range with In-Cylinder Water Injection in a Premixed Charge Compression Ignition Engine,” SAE Paper No. 2002-01-1743
- Wang, S. Miller, D.L. Cernansky, N.P. Curran, H.J. Pitz, W.J. Westbrook, C.K. 1999 “A Flow Reactor Study of Neopentane Oxidation at 8 Atmospheres: Experiments and Modeling,” Combust. Flame 118 415
- Zheng, J. Yang, W. Miller, D.L. Cernansky, N.P. 2002 “A Skeletal Chemical Kinetic Model for the HCCI Combustion Process,” SAE Paper No. 2002-01-0423
- Yang, W. Zheng, J. Miller, D.L. Cernansky, N.P. 2000 “Tracer Fuel Injection Studies on Exhaust Port Hydrocarbon Oxidation: Part II,” SAE Paper No. 2000-01-1945
- Zheng, J. Miller, D.L. Cernansky, N.P. 2003 “The Effect of Active Species in Internal EGR on Preignition Reactivity and on Reducing UHC and CO Emissions in Homogeneous Charge Engines,” SAE Paper No. 2003-01-1831
- Li, H. Miller, D.L. Cernansky, N.P. 1996 “Development of a Reduced Chemical Kinetic Model for Prediction of Preignition Reactivity and Autoignition of Primary Reference Fuels,” SAE Paper No. 960498
- Addagarla, S. Filipe, D.J. Miller, D.L. Cernansky, N.P. Green, R.M. 1991 “Effects of Speed and Manifold Pressure on Autoignition in a Motored Engine,” SAE Paper No. 910566
- Falconer, J.W. Hoare, D.E. Savaya, Z. 1983 “Peroxides in Cool Flames of Isobutane” Combustion and Flame 52 257
- Curran, H.J. Gaffuri, P. Pitz, W.J. Westbrook, C.K. 1998 “A Comprehensive Modeling Study of n-Heptane Oxidation,” Combustion and Flame 114 149