Exhaust Aftertreatment ModellingExhaust Aftertreatment Modelling

University of Thessaly Mechanical Engineering DepartmentAssoc. Prof. Dr-Ing. A.M. Stamatelos

Status March 2004

Otto & Diesel Exhaust Otto & Diesel Exhaust Aftertreatment ModellingAftertreatment 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).

Automotive Exhaust Aftertreatment: Automotive Exhaust Aftertreatment: In-house CAE Software ToolsIn-house CAE Software Tools

HEATRAN: Exhaust Systems Heat Transfer Modeling SoftwareCATRAN: 3-Way Catalytic Converter Modeling SoftwareCATRAN: NOx Adsorber Catalytic Converter Modeling SoftwareCATWALL: Diesel Particulate Filter Regeneration Modeling Software: 1D or 3D with ANSYS-CATWALL interfacingKONSTAN: Exhaust emissions test data quality assurance softwareDARWIN: Kinetic Parameter Estimation Software (based on GAs)

University of ThessalyMechanical & Industrial Engineering DepartmentLaboratory of Thermodynamics & Thermal Engines

(LTTE)

R&D Activities /funding in Automotive R&D Activities /funding in Automotive Exhaust After-Treatment CAEExhaust After-Treatment CAE

University of ThessalyMechanical & Industrial Engineering DepartmentLaboratory of Thermodynamics & Thermal Engines

(LTTE)

•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

Transfer of knowhowTransfer 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

Automotive Exhaust Aftertreatment Automotive Exhaust Aftertreatment CAE: Current state of the artCAE: 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

LTTE in-house CAE methodologiesLTTE in-house CAE methodologiesThe LTTE in-house software is tailored to the needs of the

automotive and exhaust system’s designerThe 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

Basic Features of LTTE Catalytic Basic Features of LTTE Catalytic Converter & Diesel Filter ModelsConverter & Diesel Filter Models

Kinetics: reduced pragmatic net reaction ratesDiffusion: Thiele modulus approachActivity profiles: lumped into net reaction ratesWashcoat layers: lumped into net reaction ratesHeat & mass transfer: 1-D, Nu /Sh approachCell shape: lumped into effectivenessWashcoat shape: lumped into effectivenessCanning:included (2-D for converters, 3-D for filters)Exhaust piping: included (1-D)Monolith shape and cpsi: includedEffect of Precious metal loading: empirical approachExhaust gas maldistribution: included (2-D, 3-D)Typical input data: 1-10 Hz test cycle modal dataFront-end: MS EXCEL macros or MATLAB/SIMULINK

Experimental input to CAE ToolsExperimental 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.

Further development of LTTE Further development of LTTE in-house CAE Methodologiesin-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