DOC design & sizing using GT-SUITE
European GT Conference 2017
Gauthier QUENEY
09/10/2017
Background
Predict exhaust outlet emissions
Thermal modeling
Chemical modeling
This presentation focuses on DOC only
2
Simulation tool target
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
Contents
3
After-Treatment design process1
Characterization tests2
DOC model building3
DOC model correlation4
Design optimization5
Contents
4
After-Treatment design process1
Characterization tests2
DOC model building3
DOC model correlation4
Design optimization5
After-treatment design process
5
Exhaust layout (component position) Geometry Catalyst Washcoat + PGM loading
1st analysis gives boundaries for the design process
Vehicle/Engine configuration
Regulation & emissions target
Specific operating modes
At this step:
Position, geometry are almost defined
PGM loading range is defined
Tests + Model building & calibration are next steps, before optimization
First prototype design is ready
Contents
6
After-Treatment design process1
Characterization tests2
DOC model building3
DOC model correlation4
Design optimization5
Characterization tests
Samples Light-Off performances
Steady tests (temperature steps)
Allows to isolate reactions, and keep stable concentration through various temperatures
7
Synthetic Gas Bench
Engine / Chassis Dyno test bed
Transient thermal behavior
Conversion performance on transient profiles
Contents
8
After-Treatment design process1
Characterization tests2
DOC model building3
DOC model correlation4
Design optimization5
DOC model building on GT-SUITE
9
Geometry + Thermal behaviorChemistryInput dataPost-processing
Contents
10
After-Treatment design process1
Characterization tests2
DOC model building3
DOC model correlation – SGB data4
Design optimization5
DOC model correlation – SGB data
11
CO oxidation reaction
90
120
150
180
210
240
270
300
0 100 200 300 400 500 600
Tem
pe
ratu
re [
°C]
Time [s]
Thermal correlation
Exp Model
0
20
40
60
80
100
90 120 150 180 210 240
Co
nve
rsio
n [
%]
Temperature [°C]
CO oxidation Light-Off
Exp Model
Based on SGB tests at 2 SV
Calibration
Pre-Exponent factor
Activation Energy
DOC model correlation – SGB data
12
HC storage & oxidation reaction
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
-100
-50
0
50
100
90 120 150 180 210 240 270 300
Co
nve
rsio
n [
%]
Temperature [°C]
THC storage and oxidation light-off
Exp Model
Cold storage/ adsorption
Desorption
Conversion
90
120
150
180
210
240
270
300
0 100 200 300 400 500 600
Tem
pe
ratu
re [
°C]
Time [s]
Thermal correlation
Exp Model
DOC model correlation – SGB data
13
NO oxidation reaction
Based on SGB tests at 2 SV
Basic reaction cannot fit observed behavior
Litterature study
PGM oxidation on SGB can explainthe observed phenomena : reducedconversion due to active sites loss
Thermodynamicequilibrium
0
20
40
60
80
100
100 200 300 400 500 600 700
Co
nve
rsio
n [
%]
Temperature [°C]
NO oxidation reaction - basic model
Exp Model Thermodyn. Equ
0
100
200
300
400
500
600
700
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Tem
pe
ratu
re [
°C]
Time [s]
Thermal correlation
Exp Model
DOC model correlation – SGB data
14
NO oxidation reaction
Global reversible reaction added in the surface reaction mechanism
Platinum oxidation by NO2
Calibration
Initial oxidation state
Pre-Exponent factor
Activation Energy
0
20
40
60
80
100
100 200 300 400 500 600 700
Co
nve
rsio
n [
%]
Temperature [°C]
NO oxidation reaction - PGM oxidation model
Exp Model Thermodyn. Equ
0
100
200
300
400
500
600
700
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Tem
pe
ratu
re [
°C]
Time [s]
Thermal correlation
Exp Model
DOC model correlation – SGB data
15
NO oxidation reaction
Only applicable to SGB
Basic mechanism mandatory to
represent engine conditions0
20
40
60
80
100
100 200 300 400 500 600 700
Co
nve
rsio
n [
%]
Temperature [°C]
NO oxidation reaction - PGM oxidation model
Exp Model Thermodyn. Equ
0
5
10
15
20
25
30
90 120 150 180 210 240 270 300
Co
nve
rsio
n [
%]
Temperature [°C]
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
Contents
16
After-Treatment design process1
Characterization tests2
DOC model building3
DOC model correlation – Scale 14
Design optimization5
DOC model correlation – Scale 1
17
Scale 1 thermal correlation is required to get a highaccuracy while calculating conversion
Based on transient cycle
Calibration
Geometry
Substrate & washcoat properties
− Conductivity
− Density
− Specific heat
DOC model correlation – Scale 1
18
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
Contents
19
After-Treatment design process1
Characterization tests2
DOC model building3
DOC model correlation4
Design optimization5
PGM loading optimization
20
Model allows to evaluate PGM loadings in the calibrated range (similar dispersion assumed)
PGM loading optimization
21
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%
Catalyst volume optimization
22
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%)
Additional operating point evaluation
23
Specific conditions must be checked separately to validate 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 !
0
20
40
60
80
100
120
140
0 500 1000
[km
/h]
Time [s]
Speed
650°C Target reached
Volume OK98,7% Conv
Volume OK96,8%Conv
Volume OK99,9%Conv
Volume OK100% Conv
Catalyst is well sized for DPF regeneration
Additional transient profile evaluation
24
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)
Layout design / management strategies development
25
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)
Summary
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
Simulation tool to support After-treatment design
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