Exhaust Aftertreatment Modelling

1. Exhaust Aftertreatment Modelling University of Thessaly Mechanical Engineering Department Assoc. Prof. Dr-Ing. A.M. Stamatelos Status March 2004

2. Otto & Diesel Exhaust Aftertreatment Modelling • The Laboratory of Thermodynamics & Thermal Engines of the University of Thessaly, Mechanical & Industrial Engineering Department, possesses and further develops CAE methodologies and tools regarding the modelling of Automotive Exhaust Aftertreatment Systems comprising Catalytic Converters & Diesel Filters. • Our computational tools are characterized by an engineering approach in the chemical reaction modelling, relying on apparent kinetics, partly tunable to the results of routine full scale tests (engine bench or chassis dyno tests).

3. University of Thessaly Mechanical & Industrial Engineering Department Laboratory of Thermodynamics & Thermal Engines (LTTE) Automotive Exhaust Aftertreatment: In-house CAE Software Tools HEATRAN: Exhaust Systems Heat Transfer Modeling Software CATRAN: 3-Way Catalytic Converter Modeling Software CATRAN: NOxAdsorber Catalytic Converter Modeling Software CATWALL: Diesel Particulate Filter Regeneration Modeling Software:1D or 3D with ANSYS-CATWALL interfacing KONSTAN: Exhaust emissions test data quality assurance software DARWIN: Kinetic Parameter Estimation Software (based on GAs)

4. R&D Activities /funding in Automotive Exhaust After-Treatment CAE • Fundamental Research (Long Term): • Funding provided by EC and interested Industrial Partners • Development of Computer-Aided Engineering Methodologies • (Medium Term):Funding provided by EC and Industrial Partners • Transfer of CAE Software and Knowhow (Short Term): Against • payment of license fees and charging of man-hours allocated to project • Consulting Services and Design Optimization Case Studies (Short • Term): Charging fees based on man-hours allocated to project University of Thessaly Mechanical & Industrial Engineering Department Laboratory of Thermodynamics & Thermal Engines (LTTE)

5. Transfer of knowhow • Transfer of software and knowhow to certain automotive, exhaust systems and catalytic converters manufacturers is in progress • This transfer includes understanding from our industrial partners, of the algorithm and the input and output data structures of our catalytic converter, filter & heat transfer modelling software • Cooperation with industrial partners also covers the definition and customization of experiments and tests that support the modelling of different types of catalytic converter, filter & exhaust piping

6. Automotive Exhaust Aftertreatment CAE: Current state of the art • Requirements of exhaust aftertreatment system’s performance are continuously increasing, with increasingly stringent legislation • Computer-Aided Engineering Methodologies are introduced to reduce development and testing time. They are based on in-house software • Keeping an acceptable accuracy in the prediction of emissions over the NEDC and FTP-75 cycles, becomes increasingly difficult • Commercial software (CFD) cannot be conveniently extended to cover prediction of transient exhaust emissions at converter exit

7. LTTE in-house CAE methodologies The LTTE in-house software is tailored to the needs of the automotive and exhaust system’s designer The basic points of its underlying philosophy are: • recognition of the minimum required degrees of freedom • ability to fastly and efficiently perform transient simulations • employment of routine test results in model tuning. Quality assurance of test data. • integrated system optimization based on a modular software structure that covers a wide range of aftertreatment devices

8. Basic Features of LTTE Catalytic Converter & Diesel Filter Models Kinetics: reduced pragmatic net reaction rates Diffusion: Thiele modulus approach Activity profiles: lumped into net reaction rates Washcoat layers: lumped into net reaction rates Heat & mass transfer: 1-D, Nu /Sh approach Cell shape: lumped into effectiveness Washcoat shape: lumped into effectiveness Canning:included (2-D for converters, 3-D for filters) Exhaust piping: included (1-D) Monolith shape and cpsi: included Effect of Precious metal loading: empirical approach Exhaust gas maldistribution: included (2-D, 3-D) Typical input data: 1-10 Hz test cycle modal data Front-end: MS EXCEL macros or MATLAB/SIMULINK

9. Experimental input to CAE Tools • LTTE in-house CAE methodologies use apparent kinetics and rely on full scale tests for model tuning (engine bench or chassis dyno tests, legislated cycles or parts thereof) • The results of laboratory experiments and tests that provide fundamental data (i.e. light-off, lambda sweep, oxygen storage assessment tests etc) may also be processed and taken into account in model tuning.

10. Further development of LTTE in-house CAE Methodologies • Our CAE methodologies are already being employed in automotive exhaust after-treatment design, and transferred to industrial partners • They are complete methodologies in the sense that they support the design optimization of exhaust after-treatment systems starting from routine engine bench/chassis dyno tests results • Based on this experience, our kinetics tuning, pre- and post-processing tools and methodolo-gies are further developed and customized