Potential of multiple injection strategies implementing the after shot and optimized with the design of experiments procedure to improve diesel engine emissions and performance

Abstract The potential of the after-injection versus engine-out emissions, combustion noise and brake specific fuel consumption has been evaluated for a Euro 5 diesel engine with a reduced compression ratio (16.3:1). The engine has been fueled with conventional diesel fuel. In particular, the effects of injection strategies that feature either pilot and after-injection shots, or double-pilot and single-after injection shots, have been assessed experimentally, in the presence of high EGR fractions. Calibrations with triple and quadruple injection schedules have been optimized by means of a design of experiments procedure. The performance of the thus calibrated propulsion system has been compared with data from a previously optimized double injection schedule, characterized by a retarded main injection timing in order to intensify the premixed combustion. The experimental data refer to different steady-state working conditions that are representative of passenger car engine applications over the European homologation cycle. In-cylinder analyses of the pressure, heat release rate, temperature and emissions have been performed in order to have a better understanding of the effects of the implemented injection strategies on engine performance. The substitution of the pilot-main injection schedule in the medium-high part-load zone of the NEDC region with a triple injection, featuring both pilot and after shots, has led to lower NOx and higher soot, while fuel consumption remains almost the same. In general, the EGR trade-off soot–NOx, bsfc–NOx, HC–NOx and CO–NOx curves do not change to any significant extent when an after shot is added to the pilot-main injection train. Reductions in the combustion noise, which depend on the changes in the pilot injection parameters that result from the design of experiments procedure, can also be obtained, as a consequence of the addition of the after-injection to the pilot-main injection schedule. Pilot–pilot-main-after strategies guarantee improved NOx engine-out emissions and bsfc–NOx EGR trade-off curve at medium loads and speeds, compared to both pilot–pilot-main and pilot-main-after strategies, and allow combustion noise to be diminished significantly.

[1]  T. Priede.  Problems and Developments in Automotive Engine Noise Research , 1979 .

[2]  Patrik Soltic,et al.  Experimental investigation on different injection strategies in a heavy-duty diesel engine: Emissions and loss analysis , 2011 .

[3]  Ezio Spessa,et al.  Benefits of Hydraulic Layout over Driving System in Piezo Injectors and Proposal of a New-Concept CR Injector with an Integrated Minirail , 2013 .

[4]  Nebojsa Milovanovic,et al.  Development of Premixed Low-Temperature Diesel Combustion in a HSDI Diesel Engine , 2008 .

[5]  Pascal Higelin,et al.  Combination of High EGR Rates and Multiple Injection Strategies to Reduce Pollutant Emissions , 2005 .

[6]  Stefano D'Ambrosio,et al.  Potential of double pilot injection strategies optimized with the design of experiments procedure to improve diesel engine emissions and performance , 2015 .

[7]  José M. Desantes,et al.  A Comprehensive Study of Diesel Combustion and Emissions with Post-injection , 2007 .

[8]  José V. Pastor,et al.  Insights on postinjection-associated soot emissions in direct injection diesel engines , 2008 .

[9]  Zunqing Zheng,et al.  Effect of two-stage injection on combustion and emissions under high EGR rate on a diesel engine by fueling blends of diesel/gasoline, diesel/n-butanol, diesel/gasoline/n-butanol and pure diesel , 2015 .

[10]  Hua Zhao,et al.  Experimental investigation into the effects of two-stage injection on fuel injection quantity, combustion and emissions in a high-speed optical common rail diesel engine , 2013 .

[11]  Benoist Thirouard,et al.  Using Multiple Injection Strategies in Diesel Combustion: Potential to Improve Emissions, Noise and Fuel Economy Trade-Off in Low CR Engines , 2008 .

[12]  Jian Zhuang,et al.  Effect of injection-strategy on combustion, performance and emission characteristics in a DI-diesel engine fueled with diesel from direct coal liquefaction , 2014 .

[13]  H. Ng,et al.  Homogeneous Charge Compression Ignition (HCCI) combustion: Implementation and effects on pollutants in direct injection diesel engines , 2011 .

[14]  Valeri Golovitchev,et al.  Injection Strategy Optimization for a Light Duty DI Diesel Engine in Medium Load Conditions with High EGR rates , 2009 .

[15]  S. K. Chen,et al.  Simultaneous Reduction of NOx and Particulate Emissions by Using Multiple Injections in a Small Diesel Engine , 2000 .

[16]  Kyoungdoug Min,et al.  Emission Reduction using a Close Post Injection Strategy with a Modified Nozzle and Piston Bowl Geometry for a Heavy EGR Rate , 2012 .

[17]  Rolf D. Reitz,et al.  Mechanism of Soot and NOx Emission Reduction Using Multiple-injection in a Diesel Engine , 1996 .

[18]  Federico Millo,et al.  Analysis of Multiple Injection Strategies for the Reduction of Emissions, Noise and BSFC of a DI CR Small Displacement Non-Road Diesel Engine , 2002 .

[19]  Hyun Kyu Suh,et al.  Investigations of multiple injection strategies for the improvement of combustion and exhaust emissions characteristics in a low compression ratio (CR) engine , 2011 .

[20]  Kyoungdoug Min,et al.  Experimental analysis of emission reduction by the split injection strategy using close post injection with a double-row nozzle in heavy EGR conditions , 2012 .

[21]  Andrea Catania,et al.  Premixed-Diffusive Multizone Model for Combustion Diagnostics in Conventional and PCCI Diesel Engines , 2011 .

[22]  B. Liu,et al.  Eigenvalue problems of rotor system with uncertain parameters , 2012 .

[23]  Alessandro Ferrari,et al.  The new-generation of solenoid injectors equipped with pressure-balanced pilot valves for energy saving and dynamic response improvement , 2015 .

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

[25]  C. Lambert,et al.  The Development of Advanced Urea-SCR Systems for Tier 2 Bin 5 and Beyond Diesel Vehicles , 2010 .

[26]  W. Ojeda,et al.  Development of a Fuel Injection Strategy for Partially Premixed Compression Ignition Combustion , 2009 .

[27]  Investigations of closely coupled pilot and main injections as a means to reduce combustion noise in a small-bore direct injection Diesel engine , 2014 .

[28]  Choongsik Bae,et al.  Effects of Multiple Injections in a HSDI Diesel Engine Equipped with Common Rail Injection System , 2004 .

[29]  Q. Fang,et al.  Influences of pilot injection and exhaust gas recirculation (EGR) on combustion and emissions in a HCCI-DI combustion engine , 2012 .

[30]  James E. Parks,et al.  Characterization of In-Cylinder Techniques for Thermal Management of Diesel Aftertreatment , 2007 .

[31]  Ming Zheng,et al.  Implementation of multiple-pulse injection strategies to enhance the homogeneity for simultaneous low-NOx and -soot diesel combustion , 2009 .

[32]  Balaji Mohan,et al.  Fuel injection strategies for performance improvement and emissions reduction in compression ignition engines—A review , 2013 .

[33]  Federico Millo,et al.  Experimental investigation on the effect of multiple injection strategies on emissions, noise and brake specific fuel consumption of an automotive direct injection common-rail diesel engine , 2003 .

[34]  Mark P. B. Musculus,et al.  Effect of Post Injections on In-Cylinder and Exhaust Soot for Low-Temperature Combustion in a Heavy-Duty Diesel Engine , 2010 .

[35]  Ezio Spessa,et al.  A real time zero-dimensional diagnostic model for the calculation of in-cylinder temperatures, HRR and nitrogen oxides in diesel engines , 2014 .

[36]  Ingemar Denbratt,et al.  Visualization of the Effects of Post Injection and Swirl on the Combustion Process of a Passenger Car Common Rail DI Diesel Engine , 2003 .

[37]  Seongeun Yu,et al.  Comparison of the effects of multiple injection strategy on the emissions between moderate and heavy EGR rate conditions: part 1-pilot injections , 2013 .