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Impacts On The Emissions Monitoring

System

(OBD) Due To The Use Of Biodiesel And

Higher Nox

Emissions

Leonardo de Oliveira Costa

IAV do Brasil

Rodrigo Silva Santos

IAV do Brasil

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- INTRODUCTION TO OBD

• To achieve the new emission standards (PROCONVE P7 2012), it will be needed

to control and monitoring (OBD) of exhaust gas emissions (NOx and PM);

• For engines with SCR as exhaust gas treatment technology, it will be mandatory

monitoring of exhaust gas emissions using a NOx sensor in the exhaust pipe;

• When above OBD emissions tolerances for NOx emissions, the ECU must actuate

in the engine and advise the driver;

- RENEWABLE FUELS

• The automotive industry is always looking for renewable fuels to reduce the

dependency on petroleum. Nowadays the biodiesel is the renewable fuel to replace

the diesel;

• The biodiesel has benefits about reduction of major components on the emissions

gases, ONLY increase on the NOx emissions;

• The brazilian government has a plan to increase the amount of biodiesel in the

common diesel in some years;

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- OBJECTIVE OF THE PROJECT

• Analysis the increase of NOx emissions when the engine is fueled by biodiesel

(B100) to study the influence on OBD thresholds and diagnosis.

- Tested Engine

7 liters, 6 Cylinder in Line, 4 Valves, 300HP @ 2400rpm, common-rail, EURO V

with SCR

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Global Value = 1,97g/kWh

Diesel

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Global Value = 2,6g/kWh (Increase of 32%)

B100

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Maximum increase of 80,8%

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• SCR System Overview

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• Diesel

• 1 NOx Sensor Downstream + Sensor Model Upstream

•Open Loop Dosing Control

400 ppm1000 ppm

ηηηη= 60% > 30%

Ok!

System Design 1

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• B100

• 1 NOx Sensor Downstream + Sensor Model Upstream

•Open Loop Dosing Control

720 ppm1000 ppm

ηηηη= 28% < 30%

Not Ok!

System Design 1

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• Diesel

• 1 NOx Sensor Downstream + 1 NOx Sensor Upstream

400 ppm1000 ppm

ηηηη= 60% > 30%

Ok!

System Design 2

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• B100

• 1 NOx Sensor Downstream + 1 NOx Sensor Upstream

720 ppm1800 ppm

ηηηη= 60% > 30%

Ok!

System Design 2

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• Diesel

• 1 NOx Sensor Downstream + Sensor Model Upstream

•Close Loop Dosing Control

400 ppm1000 ppm

ηηηη= 60% > 30%

Ok!

System Design 3

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• B100

• 1 NOx Sensor Downstream + Sensor Model Upstream

•Close Loop Dosing Control

720 ppm1000 ppm

ηηηη= 28% < 30%

Not Ok!

System Design 3

400 ppm

ηηηη= 60% > 30%

Ok!

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- Conclusion

• Biodiesel has a direct impact on NOx emissions value;

• and also on OBD threshold values and detection;

• on SCR System Design with only one NOx sensor, at least a close loop control

should be consider and also a low efficiency during normal Diesel operation to

make possible a efficiency increase during Biodiesel operation;

• Also a NOx sensor upstream the catalyst can be used to avoid wrong efficiency

detection and also to detect the use of Biodiesel

• Further research should be done with SCR System Design and also Biodiesel

Sensor.

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Thank you!

Leonardo de Oliveira Costa

leonardo.costa@iav.de

Rodrigo Silva Santos

rodrigo.silvasantos@iav.de