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RBEI | 07/12/2015 | © Robert Bosch Engineering and Business Solutions Private Limited 2015. All rights reserved, also regarding any disposal, exploitation,

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Impact of Fuel Quality variation on DOC & DPF system Performance - A case

study using GT-SUITE After-treatment Simulation Model

Dibakar MahalanabishRobert Bosch Engineering & Business Solutions Pvt. Ltd.

GT Conference 2015, Pune

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Contents

Introduction

Case Study Simulations:

• Variation of Temperature inlet of DOC & DPF during post injection

• Effect of Post-Injection on HC Emission and BSFC

• Performance of an Aged Catalyst

• Pressure Drop Characteristics across DPF

• Growth of Soot Layer Thickness along DPF

Sulfur Poisoning Simulations:

• DOC Configuration for Sulfur Poisoning Simulation in GT SUITE

• Initial Simulation Results on Sulfur Poisoning of DOC

• Model tuning Approach

• Comparison of Simulation Results with Test Bench Data

Conclusions

2



Introduction












Conclusions

Contents

3



Objective:

• To simulate the impact of fuel quality variation

(sulfur content of fuel) on the performance of

Exhaust After-treatment devices (DOC & DPF).

Adopted Methodology:

• Qualitative validation of GT SUITE after-treatment models through case study simulations

• Providing user-defined reactions for the DOC model to address additional sulfur poisoning reactions

• Simulation of DOC with user-defined reactions to analyze impact of sulfur poisoning on light-off temperature for HC and NOx

Introduction

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Introduction












Conclusions

Contents

5



Introduction












Conclusions

Contents

6



Location of Temperature

Measurement

Simulation Results for variation of Temperature inlet of DOC & DPF during post injection

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Retarding Post-injection increases exhaust gas temperature at the inlet of DOC.

Retarding post-injection to 75º after TDC increases DOC inlet temperature by approximately 50º C.

Comparing DPF inlet temperature (DOC outlet) it is observed that temperature at DPF inlet is slightly higher than DOC

inlet for all the cases. This can be attributed to exothermic reactions inside DOC.

Simulation Results for variation of Temperature inlet of DOC & DPF during post injection

DOC Inlet Temperature DPF Inlet Temperature

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Introduction












Conclusions

Contents

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Though, post-injection is one of the viable

solution for DPF active regeneration, it increases

the amount of unburnt hydrocarbon substantially.

Post-injection also has negative influence on

fuel economy.

Simulation Results for Effect of Post-Injection on HC Emission and BSFC

Simulation of Effect of Post-Injection on HC Emission

Simulation of Effect of Post-Injection on BSFC

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Introduction












Conclusions

Contents

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0

25

50

75

100

300 350 400 450 500 550 600 650 700

CO

Co

nvers

ion

Eff

icie

ncy (

%)

Temperature (K)

Active_Surface_Site_Density = 0.3 mol/m^3



0

25

50

75

100

400 450 500 550 600 650 700 750 800

HC

Co

nvers

ion

Eff

icie

ncy (

%)

Temperature (K)

Active_Surface_Site_Density = 0.3mol/m^3

Active_Surface_Site_Density = 0.06mol/m^3

Active_Surface_Site_Density =0.012 mol/m^3

One of the critical aspect related to performance of exhaust after-treatment devices is aging which is effectively reduction in

number of site elements on the washcoat material.

Though there is no specific parameter relating Aging of these devices in GT SUITE models, it is observed that reduction in

the active surface density can replicate performance of aged catalyst after suitable correlation.

Simulation Results for Performance of an Aged Catalyst

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Introduction












Conclusions

Contents

13



0

2

4

6

8

10

12

14

0 5000 10000 15000

Pre

ssu

re D

rop

(K

Pa)

Time (s)

Clean Filter

Initial Soot Load = 22 g



Simulation of Pressure Drop across DPF with different initial soot Load

0

1

2

3

4

5

6

7

0 10 20 30 40 50 60 70

Pre

ssu

re D

rop

(K

pa)

Soot Loading (g)

Deep-Bed

Simulation of Pressure Drop Characteristics

Simulation Results for Pressure Drop Characteristics across DPF

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Introduction












Conclusions

Contents

15



0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 5000 10000 15000 20000

So

ot

Layer

Th

ickn

ess (

mm

)

Time (s)

At Location X = 0.0

At Location X = 0.25

At Location X = 0.5

At Location X = 0.75

At Location X = 1.0

Simulation of Growth of Soot Layer Thickness along DPF

Though theoretically four different soot distributions are

possible, the most common profile suggested in literature is

parabolic.

GT SUITE model also has reported parabolic soot distribution

along the length of DPF.

Simulation Results for Growth of Soot Layer Thickness along DPF

0.08

0.09

0.1

0.11

0.12

0 0.25 0.5 0.75 1

So

ot

Layer

Th

ickn

ess (

mm

)

Normalized DPF Length

SIMULATED SOOT LAYER THICKNESS DISTRIBUTION

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Introduction












Conclusions

Contents

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Impact on DOC Performance

1. Presence of sulfur in diesel fuel results in SO2 in exhaust

gas. The catalysts in DOC facilitate the oxidation of SO2

and produce SO3. This oxidation suppresses the

necessary reactions of the toxic components of exhaust

gas (CO, HC and PM).

2. SO2 increases light-off temperature of the catalyst

substantially.

3. SO2 reacts with the wash coat material of DOC and

creates stable sulfur compounds which reduces the

quantity of active site elements and in turn reduces the

DOC conversion efficiency.

Impact on DPF Performance

1. Presence of sulfur increases the activation temperature of regeneration reaction and results in soot particles burning at higher

temperature.

2. SO3 reacts with water vapor of the exhaust gas and forms H2SO4 particles which emit through the exhaust path.

Problem Statement: Effect of Sulfur Poisoning on DOC and DPF

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Introduction












Conclusions

Contents

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DOC configuration in GT SUITE

To simulate sulfur poisoning effect, existing

GT model has to be reconfigured by adding

the additional reactions due to sulfur presence.

Reactions has to be

defined in this component

Activity Data Required

Sulfur

Poisoning

Simulation

Temperature of exhaust gas at the inlet & outlet of DOC

Exhaust mass flow rate

Composition of exhaust gas at the inlet of DOC (CO, NOx, SO2 , HC, O2 etc)

Geometrical characteristics of the catalyst: Length, Frontal Area, CPSI

Chemical characteristics of the catalyst: Site element used (PGM/ Zeolite),

Loading of site elements (g/cm3).

DOC Configuration for Sulfur Poisoning Simulation in GT SUITE

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Introduction












Conclusions

Contents

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Trends in shift of light-off temperature is observed to be followed by initial simulation results.

This indicates that inclusion of sulfurpoisoning reactions has slowed downoxidation reactions inside DOC

(Junhui et al, 2013)

(Luo et al, 2010)

𝑻𝟓𝟎 = 𝟏𝟔𝟖º 𝑪

𝑻𝟓𝟎 = 𝟏𝟗𝟔º 𝑪

Initial Simulation Results on Sulfur Poisoning of DOC

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Introduction












Conclusions

Contents

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Comparison of HC Conversion

Efficiency (%)

Comparison of DOC Outlet

Temperature (º C)

DOC Inlet Temperature

Composition of Exhaust gas at DOC Inlet

Exhaust Volume flow rate

GT SUITE

DOC Model

Model tuning Approach

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Introduction












Conclusions

Contents

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350 ppm

50 ppm

The possible deviation may be due tothe variation of physical parametersof DOC (CPSI, frontal area etc.).

Maximum efficiency in simulation isfound to be lower than experiments.This may be due to assumptionsmade in the composition of NMHC(non-methane hydrocarbon).

Further fine tuning of the model withrespect to chemical kineticsparameters (activation energy, pre-exponent multiplier) will result inimproved accuracy.

50 ppm

350 ppm

Comparison of Simulation Results with Test Bench Data

26

Experiments are carried out on a 4-cylinder turbocharged engine



Introduction












Conclusions

Contents

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GT-SUITE After-treatment models are capable of replicating true physical behaviours of after-treatment

devices.


GT-SUITE After-treatment models can be effectively used to simulate the impact of sulfur poisoning on the

performance of DOC and DPF.

In future findings of these simulations can be utilized in development of improved functionalities on ECU for

predicting performance deterioration of exhaust after-treatment devices due to fuel quality variations.

Conclusions

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I would like to thank the following people for their help during this work:

• Mr. Pradeep Kumar Keloth, Department Head, EEI, RBEI

• Mr. Aurobbindo Lingegowda, Project Manager, EEI4, RBEI

• Mr. Samrat G K, Expert, EEX, RBEI

Acknowledgements

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• Junhui, L., Kumar, A., Chen, X., Currier, N., Yezerets, A. (2013) Impact of Different Forms of Sulfur Poisoning on Diesel

Oxidation Catalyst Performance, SAE International doi:10.4271/2013-01-0514

• Luo, J., Kisinger, D., Abedi, A., Epling, W. (2010) Sulfur release from a model Pt/Al2O3 diesel oxidation catalyst:

Temperature-programmed and step-response techniques characterization, Appl. Catal. A: Gen. 383 (2010) 182-191

• Cabello, G. F., Laresea, C., Mariscala, R., Granadosa, M. L., Fierroa, J. L. G., Fernandez, R. R., Furio, M. (2004)

Deactivation on vehicle-aged diesel oxidation catalysts, Topics in Catalysis Vols. 30/31, July 2004.

References

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Thank You!

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impact of fuel quality variation on doc & dpf … › wp-content › uploads › 2016 › 01 ›...

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