A high pressure EGR system was adopted to a turbocharged inter-cooled diesel engine, to analyze its combustion and emission characteristics under the condition of different loads and constant speed. Under the same steady operating mode, with the increase of EGR rate, the temperature of compressed gas ascended, the ignition delay was shortened, the pressure and temperature of the burned gas descended, and the combustion process was prolonged. According to the experimental data, it was found that, at the same EGR rate, lower the load of engine was, lower the temperature in cylinder, and higher the increase rate of CO was. However, the increase rate of HC present a falling trend. The decrease rate of the specific emission of NOx linearly varied with EGR rate with a slope of 1.651. The increase rate of smoke opacity behaved a second-order polynomial uprising trend, and the higher the load was, the sharpener the smoke opacity deteriorated, with the increase of EGR rate. From the point of emission view, the engine with EGR system can achieve the lesser exhaust emissions in some operations by adjusting the engine parameters. 1. Introduction Saving oil resources and reducing the emissions of greenhouse gases have become the worldwide consensus when the earth is faced with the environment and energy sources challenges [1–3]. Direct-injection diesel engine has become the preference of commercial vehicles due to its high thermal efficiency and has been applied to 15 to 30 percent passenger cars in Euro-American markets. Meanwhile, regulations on the harmful exhaust emissions coming from engines have been increasingly stringent [4, 5]. Turbocharging, high-pressure fuel injection, exhaust gas recirculation (EGR), electronic-control fuel supply system, and exhaust after-treatments successfully used in combination successively have become technical measures [6] to comply with emission legislations of various stages. Among technical routes to implement the emission control, the EGR system is an external device used to control N O x emissions [7, 8], which has been regarded as an in-engine purification measure for reorganizing the intake and adjusting the in-cylinder combustion process [9]. The mechanism of EGR system reducing N O x emissions is introducing parts of the exhaust gas into the combustion chamber to increase the heat capacity of gases, lower the temperature of burning gases, and thus reduce the N O x emission. Because EGR would result in the combustion lag and reduced the temperature [10], there is also a possibility that the exhaust of HC, CO, and PM would
References
[1]
T. A. Boden, G. Marland, and R. J. Andres, Global, Regional, and National Fossil-Fuel CO2 Emissions, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn, USA, 2009.
[2]
R. Ewing, A. C. Nelson, K. Bartholomew, P. Emmi, and B. Appleyard, “Response to special report 298 driving and the built environment: the effects of compact development on motorized travel, energy use, and CO2 emissions,” Journal of Urbanism, vol. 4, no. 1, pp. 1–5, 2011.
[3]
Z. Songli, “The effect of diesel vehicle on saving energy and cutting greenhouse gas,” Energy Conservation And Environmental Protection, vol. 7, pp. 9–11, 2006.
[4]
G. F. Allen and M. Lewis, “Finding the proper forum for regulation of u.s. greenhouse gas emissions: the legal and economic implications of massachusetts v. EPA,” envisioning energymarch, 44 U. Rich. L. Rev. 919, 2010.
[5]
J. McCarthy, “EPA regulation of greenhouse gases: congressional responses and options,” 2010.
[6]
H. Zhiyu, C. Zheng, L. Jingping, and L. Yun, “Modern diesel engine technology for passenger cars,” Engineering Sciences, pp. 36–38, 2009.
[7]
E. Rajasekar, A. Murugesan, R. Subramanian, and N. Nedunchezhian, “Review of NOx reduction technologies in CI engines fuelled with oxygenated biomass fuels,” Renewable and Sustainable Energy Reviews, vol. 14, no. 7, pp. 2113–2121, 2010.
[8]
Z. Zhendong, C. Chaomei, and Z. Ping, “Design of an EGR control system for a supercharged direct-injection diesel egnine,” Automotive-Engineering, vol. 26, no. 2, pp. 136–138, 2004.
[9]
H. Wenjun, “Application of EGR technology on diesel engine,” Small Internal Combustion Engine and Motorcycle, vol. 37, no. 1, pp. 75–78, 2008.
[10]
M. Fathia, R. K. Sarayb, and M. D. Checkelc, “The influence of exhaust gas recirculation (EGR) on combustion and emissions of n-heptane/natural gas fueled homogeneous charge compression ignition (HCCI) engines,” Applied Energy Journal, vol. 10, p. 1016, 2011.
[11]
G. Changming, Y. Shufangetc, et al., “Emission characteristics of automobile turbocharged diesel engine with EGR,” Transactions of The Chinese Society for Agricultural Machinery, vol. 36, no. 4, pp. 144–146, 2005.
[12]
S. O. Wasiu, S. A. Sulaiman, and A. R. A. Aziz, “An experimental study of different effects of EGR rates on the performance and exhaust emissions of the stratified charge piston direct injection compressed natural gas engine,” Journal of Applied Sciences, vol. 11, no. 9, pp. 1479–1490, 2011.
[13]
F. Zuhua, L. guihua, and S. Guanping, “The structure plans and key technologies of EGR system in turbo-charged, direct-injected diesel engines,” Internal Combustion Engines, vol. 3, pp. 15–17, 2003..
[14]
K. Anand, R. P. Sharma, and P. S. Mehta, “Experimental investigations on combustion, performance, and emissions characteristics of a neat biodiesel-fuelled, turbocharged, direct injection diesel engine,” Journal of Automobile Engineering, vol. 224, no. 5, pp. 661–679, 2010.
[15]
N. Ladommatos, S. M. Abdelhalim, H. Zhao, and Z. Hu, “The effects on diesel combustion and emissions of reducing inlet charge mass due to thermal throttling with hot EGR,” in Proceedings of the SAE International Congress & Exposition, pp. 97–109, February 1998.
[16]
A. K. Sarangi, G. P. McTaggart-Cowan, and C. P. Garner, “The effects of intake pressure on high EGR low temperature diesel engine combustion,” in Proceedings of the SAE Powertrains Fuels & Lubricants Meeting, San Diego, CA, USA, October 2010.
