Injection Strategy Optimization for a Light Duty DI Diesel Engine in Medium Load Conditions with High EGR rates

Further restrictions on NOx emissions and the expansion of current driving cycles for passenger car emission regulations to higher load operation in the near future (such as the US06 supplement to the FTP-75 driving cycle) requires attention to low emission combustion concepts in medium to high load regimes. One possibility to reduce NOx emissions is to increase the EGR rate. The combustion-temperature reducing effects of high EGR rates can significantly reduce NO formation, to the point where engine-out NOx emissions approach zero levels. However, engine-out soot emissions typically increase at high EGR levels, due to the reduced soot oxidation rates at reduced combustion temperatures and oxygen concentrations. The work presented in this paper focuses on the optimization of a triple injection strategy to study the effect of injection timing, fuel mass distribution over the different injections and fuel rail pressure on emissions, combustion noise and fuel consumption for operation at medium load (10 bar IMEP and upwards) and high EGR rates (41%). The results of some of the test cases are compared with those obtained from modelling in KIVA-3V. By using an optimized triple injection strategy, soot emission levels could be reduced to below 0.04 g/kWh and NOx emissions to below 0.4 g/kWh at a medium engine load of 10 bar IMEP in a single cylinder research engine.

[1]  V. I. Golovitchev,et al.  Spray Combustion Simulation Based on Detailed Chemistry Approach for Diesel Fuel Surrogate Model , 2003 .

[2]  Takeyuki Kamimoto,et al.  High Combustion Temperature for the Reduction of Particulate in Diesel Engines , 1988 .

[3]  R. Reitz,et al.  MODELING SPRAY ATOMIZATION WITH THE KELVIN-HELMHOLTZ/RAYLEIGH-TAYLOR HYBRID MODEL , 1999 .

[4]  A. A. Amsden,et al.  KIVA-3V: A Block-Structured KIVA Program for Engines with Vertical or Canted Valves , 1997 .

[5]  Charles J. Mueller,et al.  The Quantification of Mixture Stoichiometry When Fuel Molecules Contain Oxidizer Elements or Oxidizer Molecules Contain Fuel Elements , 2005 .

[6]  Rolf D. Reitz,et al.  Six-Mode Cycle Evaluation of the Effect of EGR and Multiple Injections on Particulate and NOx Emissions from a D.I. Diesel Engine , 1996 .

[7]  John E. Dec,et al.  A Computational Study of the Effects of Low Fuel Loading and EGR on Heat Release Rates and Combustion Limits in HCCI Engines , 2002 .

[8]  Ronald K. Hanson,et al.  Shock tube determination of ignition delay times in full-blend and surrogate fuel mixtures , 2004 .

[9]  Lucien Koopmans,et al.  A Four Stroke Camless Engine, Operated in Homogeneous Charge Compression Ignition Mode with Commercial Gasoline , 2001 .

[10]  J. Chomiak,et al.  3-D Diesel Spray Simulations Using a New Detailed Chemistry Turbulent Combustion Model , 2000 .

[11]  Bengt Johansson,et al.  The Effect of Cooled EGR on Emissions and Performance of a Turbocharged HCCI Engine , 2003 .

[12]  K. Akihama,et al.  Mechanism of the Smokeless Rich Diesel Combustion by Reducing Temperature , 2001 .

[13]  J. Naber,et al.  Effects of Gas Density and Vaporization on Penetration and Dispersion of Diesel Sprays , 1996 .

[14]  Rolf D. Reitz,et al.  Reducing Particulate and NOx Using Multiple Injections and EGR in a D.I. Diesel , 1995 .

[15]  Cherian A. Idicheria,et al.  Soot Formation in Diesel Combustion under High-EGR Conditions , 2005 .

[16]  Ingemar Denbratt,et al.  HCCI Operation of a Passenger Car DI Diesel Engine with an Adjustable Valve Train , 2006 .

[17]  Arjan Helmantel.  Reduction of NOx Emissions from a Light Duty DI Diesel Engine in Medium Load Conditions with High EGR Rates , 2008 .