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Predictive modeling of combustion and emissions behavior in diesel and PPC engines

Predictive modeling of combustion and emissions behavior in diesel and PPC engines. Xue-Song Bai, Mehdi Jangi Dept of Energy Sciences, Lund University Eric Baudoin , Raymond Reinmann, Niklas Nordin Scania CV AB. Motivation. Diesel engine development High efficiency

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Predictive modeling of combustion and emissions behavior in diesel and PPC engines

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  1. Predictive modeling of combustion and emissions behavior in diesel and PPC engines Xue-Song Bai, Mehdi Jangi Dept of Energy Sciences, Lund University Eric Baudoin, Raymond Reinmann, Niklas Nordin Scania CV AB

  2. Motivation • Diesel engine development • High efficiency • Low emissions of NOx, soot • Current solutions, among others • Advanced injection strategy with EGR • Non-conventional combustion mode: PPC • R&D approaches • Engine experiments • CFD simulations • CFD simulations are widely used in engine design • Used in all major engine companies • Cost-effective, 4-dimensional data, great potential • In USA Wisconsin group demonstrated the potential of CFD

  3. Engine design and optimization • Large number of parameters, thousands CFD run cases • Injection strategies: nozzle, angles, timing, fuel type • EGR and inlet temperature, incylinder pressure • Piston/cylinder geometry • Turbulence intensity, swirl • Engine combustion model efficiency is of concern • Chemistry coupling with the flow is important for PPC • We developed a novel chemistry coordinate mapping (CCM) • State-of-art engine combustion CFD modeling • Considerable test of models for SI and diesel engines • Not well tested for PPC or diesel with EGR or alternative fuels • Not predictive • Accuracy and cost tradeoff

  4. Accuracy and efficiency accuracy Detailed chemistry, LES-CCM Detailed chemistry, LES Detailed chemistry, RANS-CCM Detailed chemistry, RANS Simplified chemistry, RANS cost

  5. Project goals and deliverables • Develop and systematically test the CFD tools and models • models used presently in industry and academics • under challenging diesel engines/PPC engines conditions • working with the OpenFoam platform • Carrying out real engine experiments • serves as validation of the CFD models • baseline case for testing advanced engine concept • Development of a guideline for the use of various CFD models • model accuracy (requiring detailed chemistry) • computational efficiency (CCM approach, focus of this project) • under various diesel/PPC engine-operating and fuel conditions.

  6. Achievements • Evaluation of RANS based chemistry coordinate mapping (CCM) models under ECN Spray A conditions. • Evaluation of LES-CCM models using ECN cases with n-Dodecane and n-Heptane fuel under varying conditions. • A comparison of RANS-CCM and LES-CCM approaches is investigated based on the ECN cases. • Development of a new turbulence/chemistry interaction model, based on CCM and transported probability density function (PDF). • Engine experiment campaign at Scania are carried out with model fuels.

  7. High efficiency transported PDF approach Notional particles are tracking in physical space Haworth, Prog. Energy Combust. 2010 168-259 Particles mapped to the phase-space for solving chemistry’s ODEs - Several particles at similar thermodynamic states grouped into one zone in the phase-space. - Integration of the stiff ODEs is perform in the zones and the results are mapped back to the particles - Speedup the integration of stiff ODEs by a factor of 30.

  8. UC Berkeley viciated flame Methane jet discharging into high temperature atmosphere Cabra’s methane lifted flame: Velocity [m/s] YCH4 YO2 T [K] Jet 100 0.213 0.188 320 Co-flow 0.9 0 0.141 1310-1350 Cabra et al. Combust. Flame 143 (4) (2005) 491–506. DRM22 with 22 species and 74 reactions

  9. UC Berkeley viciated flame (b): coflow T= 1310 K (case C10) (a): coflow T= 1350 K (case C50)

  10. UC Berkeley viciated flame

  11. Sandia engine with multiple injections J. O’Connor et al. (2013) experiments Engine base type: Cummins N-14, DI diesel Bore: 139.7 mm Stroke: 152.4 Geometric compression ration: 11.2 Intake O2: 12.6 % Injection: One main injection followed by a post injection

  12. Sandia engine with multiple injections Temperature field, blue-red range is 400-1100 K

  13. Ongoing work • Further engine experiment campaign at Scania are ongoing • Application of LES/RANS CCM/PDF models to study of the Scania engines, to improve the understanding of the mixing and combustion process for improvement of the design.

  14. Thank you for your attention

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