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