Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg 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

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg 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

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg 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

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg Accuracy and efficiency accuracy cost Detailed chemistry, LES Simplified chemistry, RANS Detailed chemistry, RANS Detailed chemistry, LES-CCM Detailed chemistry, RANS-CCM

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg 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.

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg 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.

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg 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. High efficiency transported PDF approach

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg DRM22 with 22 species and 74 reactions Methane jet discharging into high temperature atmosphere UC Berkeley viciated flame

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg (a): coflow T= 1350 K (case C50) (b): coflow T= 1310 K (case C10) UC Berkeley viciated flame

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg UC Berkeley viciated flame

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg Sandia engine with multiple injections Engine base type: Cummins N-14, DI diesel Bore: mm Stroke: Geometric compression ration: 11.2 Intake O 2: 12.6 % Injection: One main injection followed by a post injection J. O’Connor et al. (2013) experiments

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg Temperature field, blue-red range is K Sandia engine with multiple injections

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg 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.

Energirelaterad fordonsforskning 2014, oktober 8-9, Göteborg Thank you for your attention