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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.