Modeling the Effect of Variable Timing of the Exhaust Valves on SI Engine Emissions for Greener Vehicles

Osama H. M. Ghazal, Yousef S. H. Najjar, Kutaeba J. M. Al-Khishali

Mechanical Engineering Department, Applied Science Private University, Amman, Jordan.
Mechanical Engineering Department, Jordan University of Science and Technology, Amman, Jordan.
Mechanical Engineering Department, Philadelphia University, Amman, Jordan.

DOI: 10.4236/epe.2013.53018                

Abstract

The problem with fixed valve timing that the valve train is set by the automaker for peak efficiency running at a specific point in the engine’s operating range. When the vehicle is moving slower or faster than this ideal operating point the engine’s combustion cycle fails to properly burn the air/fuel mixture leading to considerably compromised engine performance and wastes fuel. Variable Valve Timing (VVT) is a solution developed to overcome this engine deficiency, dynamically altering the valve's opening and closing for optimal performance at any speed. The intension in this work is to contribute towards pursuing the development of variable valve timing (VVT) for improving the engine performance. This investigation covers the effect of exhaust valve opening (EVO), and closing (EVC) angle on engine performance and emissions. The aim is to optimize engine power and brake specific fuel consumption (BSFC) where the effect of engine speed has also been considered. Power, BMEP, BSFC, NO, and CO were calculated and presented to show the effect of varying valve timing on them for all the valve timing cases. The calculations of engine performance were carried out using the simulation and analysis engineering software: LOTUS”, and engine emissions were calculated using “ZINOX” program. Sensitivity analysis shows that the reduction of 10% of (EVO) angle gave a reduction of around 2.5% in power and volumetric efficiency, also a slight increase in nitrogen oxide (NO) and carbon monoxide (CO), while a 10% decrease in (EVC) causes around 1% improvement in Power. The effects of different (VVT) from the simulations are analyzed and compared with those in the reviewed literature.

Keywords

Variable Exhaust Valve Timing; Spark Ignition Engines; Performance; Emissions; Green Vehicles

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	G. Fontana and E. Galloni, “Variable Valve Timing for Fuel Economy Improvement in a Small Spark-Ignition Engine,” Applied Energy, Vol. 86, No. 1, 2009, pp. 96-105. doi:10.1016/j.apenergy.2008.04.009
[2]	T. Ahmad and M. Thobald, “A Survey of Variable Valve Actuation Technology,” SAE, New York, SAE Paper 89, 674, 1989.
[3]	O. H. Ghazal, Y. S. Najjar and K. J. Al-Khishali, “Effect of Inlet Valve Variable Timing in the Spark Ignition Engine on Achieving Greener Transport,” World Academy of Science, Engineering and Technology, Vol. 59, 2011, pp. 1073-1077.
[4]	S. Shiga, S. Yagi, M. Morita, T. Matsumoto, T. Krasawa, and T. Nakamura, “Effects on Valve Close Timing for Internal Combustion Engines,” Transactions of the Japan Society of Mechanical Engineers, Vol. 62, No. 596, 1996, pp. 1659-1665.
[5]	H. Hong, G. B. Parvate-Patil and B. Gordon, “Review and Analysis of Variable Valve Timing Strategies—Eight Ways to Approach,” Journal of Automobile Engineering, Vol. 218, No. 10, 2004, pp. 1179-1200. doi:10.1177/095440700421801013
[6]	N. Kosuke, K. Hiroyuki and K. Kazuya, “Valve Timing and Valve Lift Control Mechanism for Engines,” Mechatronics, Vol. 16, No. 2, 2006, pp. 121-129. doi:10.1016/j.mechatronics.2005.09.007
[7]	F. Bozza, A. Gimelli, A. Senatore and A. Caraceni, A Theoretical Comparison of Various VVA Systems for Performance and Emission Improvements of SI-Engines, SAE Paper 2001-010-0670, 2001.
[8]	F. Bonatesta and P. J. Shayler, “Factors Influencing the Burn Rate Characteristics of a Spark Ignition Engine with Variable Valve Timing,” Journal of Automobile Engineering, Vol. 222, No. 11, 2008, pp. 1963-1974. doi:10.1243/09544070JAUTO873
[9]	L. Cao, H. Zhao, X. Jiang and N. Kalian, “Unstanding the Influence of Valve Timings on Controlled Auto-Ignition Combustion in a Four-Stroke Port Fuel Injection Engine,” Journal of Automobile Engineering, Vol. 219, No. 6, 2005, pp. 807-823. doi:10.1243/095440705X11077
[10]	N. Milovanovic, R. Chen and J. Turner, “Influence of Variable Valve Timings on the Gas Exchange Process in a Controlled Auto-Ignition Engine,” Journal of Automobile Engineering, Vol. 218, No. 5, 2004, pp. 567-583. doi:10.1243/095440704774061228
[11]	Y. Ping, X. Zhang, Y. Dong, G. Zhu and Q. Wang, “Study on Performance Improvement of Vehicle Engine by Using Variable Cam Timing,” Neiranji Gongcheng/ Chinese Internal Combustion Engine Engineering, Vol. 29, No. 6, 2008, pp. 20-23.
[12]	T. Rychter and A. Teodorczyk, “Teoria Silnikow Tlokowych,” 1st Edition, WKiL Company, Warszawa, 2006.
[13]	G. Lavoie, J. B. Heywood and C. J. Keck, “Experimental and Theoretical Study of Nitric Oxide Formation in Internal Combustion Engines,” Combustion Science and Technology, Vol. 1, No. 4, 1970, pp. 313-326. doi:10.1080/00102206908952211
[14]	R. Stone, “Introduction to Internal Combustion Engines,” 3rd Edition, McMillan Press, London, 1999.
[15]	Habempirische Formel fur Die Verbrennungsgeschrwin digkeit Verlag der Akademie der Wissenschaften der VdSSR I.Wiebe Moscow (1956)R.
[16]	W. J. D. Annand, “Heat Transfer in the Cylinder of Reciprocating Internal Combustion Engines,” Proceedings of the Institution of Mechanical Engineers, Vol. 177, No. 1, 1963, pp. 973-996.
[17]	W. A. Woods and S. R. Khan, “An Experimental Study of Flow through Poppet Valves,” Proceedings of the Institution of Mechanical Engineers, Vol. 180, No. 14, 1965, pp. 32-41.
[18]	R. S. Benson, “The Thermodynamics and Gas Dynamics of Internal Combustion Engines,” Vol. 1, Clarendon Press, Oxford, 1982.