DOC design & sizing using GT-SUITE European GT Conference Gauthier QUENEY 09/10/2017

Transcription

1 DOC design & sizing using GT-SUITE European GT Conference 2017 Gauthier QUENEY 09/10/2017

2 Background Simulation tool target Predict exhaust outlet emissions Thermal modeling Chemical modeling This presentation focuses on DOC only Why using a simulation tool? Support exhaust architecture design (thermal optimization) Preselect catalyst (PGM loading, technology ) for required emission performance Perform fast parametric studies & optimization without vehicle/engine 2

3 Contents 1 After-Treatment design process 2 Characterization tests 3 DOC model building 4 DOC model correlation 5 Design optimization 3

4 Contents 1 After-Treatment design process 2 Characterization tests 3 DOC model building 4 DOC model correlation 5 Design optimization 4

5 After-treatment design process 1st analysis gives boundaries for the design process Vehicle/Engine configuration Regulation & emissions target Specific operating modes Exhaust layout (component position) Geometry Catalyst Washcoat + PGM loading At this step: Position, geometry are almost defined PGM loading range is defined First prototype design is ready Tests + Model building & calibration are next steps, before optimization 5

6 Contents 1 After-Treatment design process 2 Characterization tests 3 DOC model building 4 DOC model correlation 5 Design optimization 6

7 Characterization tests Synthetic Gas Bench Samples Light-Off performances Steady tests (temperature steps) Allows to isolate reactions, and keep stable concentration through various temperatures Engine / Chassis Dyno test bed Transient thermal behavior Conversion performance on transient profiles 7

8 Contents 1 After-Treatment design process 2 Characterization tests 3 DOC model building 4 DOC model correlation 5 Design optimization 8

9 DOC model building on GT-SUITE Geometry + Thermal behavior Chemistry Input data Post-processing 9

10 Contents 1 After-Treatment design process 2 Characterization tests 3 DOC model building 4 DOC model correlation SGB data 5 Design optimization 10

11 Temperature [ C] Conversion [%] DOC model correlation SGB data CO oxidation reaction CO oxidation Light-Off Exp Model Temperature [ C] Based on SGB tests at 2 SV Thermal correlation Exp Model Time [s] Calibration Pre-Exponent factor Activation Energy 11

12 Temperature [ C] Conversion [%] DOC model correlation SGB data HC storage & oxidation reaction THC storage and oxidation light-off 100 Cold storage / adsorption Exp Model 50 Conversion Desorption Temperature [ C] Thermal correlation Exp Model Time [s] Based on SGB tests at 2 SV 2 modelled HC 1 light for fast oxidation 1 heavy for storage and slow oxidation Calibration Initial coverage Pre-Exponent factor Activation Energy 12

13 Temperature [ C] Conversion [%] DOC model correlation SGB data NO oxidation reaction NO oxidation reaction - basic model Exp Model Thermodyn. Equ Thermodynamic equilibrium Based on SGB tests at 2 SV Basic reaction cannot fit observed behavior Temperature [ C] Thermal correlation Exp Model Litterature study PGM oxidation on SGB can explain the observed phenomena : reduced conversion due to active sites loss Time [s] 13

14 Temperature [ C] Conversion [%] DOC model correlation SGB data NO oxidation reaction 100 NO oxidation reaction - PGM oxidation model Exp Model Thermodyn. Equ Temperature [ C] Thermal correlation Exp Model Time [s] Global reversible reaction added in the surface reaction mechanism Platinum oxidation by NO2 Calibration Initial oxidation state Pre-Exponent factor Activation Energy 14

15 Conversion [%] Conversion [%] DOC model correlation SGB data NO oxidation reaction 100 NO oxidation reaction - PGM oxidation model Exp Model Thermodyn. Equ Temperature [ C] Only applicable to SGB Basic mechanism mandatory to represent engine conditions NO oxidation reaction PGM oxidation model Exp Model At that point : - Chemical model calibrated (sample scale) for several PGM loading / on the studied range of Temp, SV and composition Temperature [ C] 15

16 Contents 1 After-Treatment design process 2 Characterization tests 3 DOC model building 4 DOC model correlation Scale 1 5 Design optimization 16

17 DOC model correlation Scale 1 Scale 1 thermal correlation is required to get a high accuracy while calculating conversion Based on transient cycle Calibration Geometry Substrate & washcoat properties Conductivity Density Specific heat 17

18 DOC model correlation Scale 1 SGB fit requires fine extra calibration due to SGB representativity versus engine Regulation Regulation Regulation At that point : - Chemical model calibrated for several PGM loading / on the studied range of Temp, SV and composition - Predictive thermal model - DOC well sized regarding regulation target Model is ready to optimize volume / PGM loading 18

19 Contents 1 After-Treatment design process 2 Characterization tests 3 DOC model building 4 DOC model correlation 5 Design optimization 19

20 PGM loading optimization Model allows to evaluate PGM loadings in the calibrated range (similar dispersion assumed) 20

21 PGM loading optimization Model allows to evaluate PGM loadings in the calibrated range (similar dispersion assumed) In that specific case : - NEDC cycle in normal operating mode specific conditions as DPF regeneration excluded - Without taking any safety margin PGM loading could be reduced by 70% 21

22 Catalyst volume optimization Model allows to evaluate several catalyst volumes in the calibrated range In that specific case : - NEDC cycle in normal operating mode - Without taking any safety margin Catalyst is well sized regarding volume, slight optimization possible (10 to 20%) 22

23 [km/h] Additional operating point evaluation Specific conditions must Catalyst be checked is well separately sized for DPF to validate regeneration design DPF regen example Oper. Point 120 km/h NEDC 150kg/h 375 C DOC in Gas T Target : 650 C DOC out Gas T From 400 to 15000ppm THC injection! Volume OK 99,9%Conv Volume OK 100% Conv Speed Time [s] Volume OK 96,8%Conv Volume OK 98,7% Conv 650 C Target reached 23

24 Additional transient profile evaluation Model allows to evaluate additional transient profiles WLTC example No additional calibration requested if similar range of Temperature, SV, composition Allow to check performance or compliance on other transient profiles Design validation on various transient profiles (ex: Real Driving Emissions) 24

25 Layout design / management strategies development Model allows to evaluate layout configuration / management strategies Insulation / Heat-up strategy +50 C for 100s example No additional calibration requested if similar range of Temperature, SV, composition Application possible Insulation / Catalyst position Heat-up strategies Engine internal emissions reduction (ex: EGR) strategies Etc Not-available parameters evaluation possible (ex: Engine management strategies) 25

26 Summary Simulation tool to support After-treatment design Allows to estimate behavior of non-available configurations (inside the same range) Help us supporting OEM through calibration / layout design Reduces test numbers if boundaries well defined Still request knowledge for 1st design Saves time optimizing design Methodology approved by 1 OEM 26

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