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F. Bozza M.C. Cameretti A. Senatore R. Tuccillo Dipartimento di Ingegneria Meccanica per l’Energetica (D.I.M.E.) Università di Napoli “Federico II” Naples, Italy 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97

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Engine Specifications Author’s background: The behavior of a light-duty Turbocharged Diesel Engine is analyzed by means of: Experimental activities Numerical simulation 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 2 of 25

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To improve the understanding of unsteady engine operation by looking at in-cylinder details and to the whole system behavior A fully theoretical prediction of EGR influence on both engine performance and NOx emissions An integrated computational procedure: A Flow Model (1D TVD approach) A Combustion Model (KIVA II code) allows the desired characterization of the Turbocharged engine operation 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 3 of 25

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A first characterization of the tested engine through the acquisition of: Time-average and instantaneous data Performance and emission parameters In-cylinder multidimensional analysis: Improved KIVA II code normal and EGR operation different Load conditions Whole system simulation with EGR : 1D Flow Model in external ducts Turbocharger equilibrium computation In-cylinder analysis is then improved at the updated operating conditions 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 4 of 25

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Experimental Equipment Experimental tests were carried out at constant speed operation (3000 rpm) Both time-averaged and instantaneous data are acquired: 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 5 of 25

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Equivalence Ratio Torque Power Spec. Fuel Cons. Exhaust Gas composition analysis Performance Data Equivalence Ratio 3000 rpm [kW] O 2 [g/kWh] g/kWh [Nm] CO 2 [g/kWh] NO X [g/kWh] CO [g/kWh] 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 6 of 25

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Pressure, bar Crank Angle, deg Pressure, bar Crank Angle, deg Lift [%] Equivalence Ratio 0.31 - 34% Load 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 7 of 25

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Equivalence Ratio 0.45 - 65% Load Pressure, bar Crank Angle, deg Pressure, bar Crank Angle, deg Lift [%] 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 8 of 25

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Pressure, bar Crank Angle, deg Pressure, bar Crank Angle, deg Lift [%] Equivalence Ratio 0.63 - Full Load 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 9 of 25

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A velocity profile is computed employing experimental data on Needle Lift and Injection Pressure: Improvements in multidimensional calculations were obtained on: Fuel injection process simulation Ignition delay calculation Thermal NO formation kinetics 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 10 of 25

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Crank Angle, deg Injected Fuel Velocity, m/s Injected Fuel Mass, g 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 11 of 25

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The correlation of Stringer et al. holds in a pressure and temperature range close to that of the tested Turbocharged engine: The original algorithm of solution was replaced by the sequential solution of the extended Zel’dovich kinetics equations: 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 12 of 25

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A predictor-corrector method was employed with an automatic reduction of the time step: A constant temperature test demonstrates the absence of fluctuations up to the NO equilibrium level: 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 13 of 25 A relevant increase of computational time!

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Crank Angle, deg Pressure, bar Temperature, K 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 14 of 25 Normal Operation (No EGR)

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Crank Angle, deg Fuel Burned Fraction [NO], p.p.m. 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 15 of 25

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Crank Angle, deg Pressure, bar Temperature, K 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 16 of 25

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Crank Angle, deg Fuel Burning Rate, 1/deg [NO], p.p.m. 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 17 of 25

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Crank Angle, deg Fuel Burning Rate, 1/deg [NO], p.p.m. 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 18 of 25

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NO EGR 12% EGR 7% EGR NO Levels p.p.m. Full Load 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 19 of 25 10° aTDC

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Initial conditions at IVC exert a great influence on start of combustion, burning rate profile and emission characteristics Moreover, the EGR amount is itself unknown! The interaction between the in-cylinder processes, external flows and turbocharger operation imposes to analyze the system as a whole Variations at IVC are induced by EGR as a consequence of different engine and turbocharger matching conditions 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 20 of 25

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An integrated data exchange procedure between a 1D Model and KIVA code has been developed: Initial P,T,m,EGR at IVC KIVA Theor. Heat Release 1D Flow Updated Conditions at IVC ? Converged Theoretical ROHR and wall heat transfer are derived from KIVA calculation: 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 21 of 25

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2nd Order, Finite Volume upwind scheme Total Variation Diminishing (TVD) Technique ICE97 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 22 of 25 Scalar transport eqs. of residual, x r, and fuel, x f, gas fractions for the evaluation of a correct gas composition with EGR active

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Crank Angle, deg Pressure, bar Temperature, K 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 23 of 25 Crank Angle, deg

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Fuel Burning Rate, 1/deg [NO], p.p.m. 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 24 of 25

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Main results found: Future work: assessment of the methodology and improvement of 1D e 3D models for a more direct comparison with experimental data. The integrated computational procedure between: A Flow Model (1D TVD approach) A Combustion Model (KIVA II code) together with experimental data, allows to fully characterize the Turbocharged engine under EGR operation. Appropriate initial conditions are of fundamental importance for realistic evaluations of in-cylinder phenomena 3 rd International Conference : Experiments and Modeling Consiglio Nazionale delle Ricerche Istituto Motori ICE97 Bozza F., et al., DIME, University of Naples, ITALY A Flow and Combustion Model for NO X …, p. 25 of 25

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