20-04-2010, 10:00 PM
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Basic Emission Control Systems
Need of Emission Control System
Global warming
Acid rain
Smog
Odours
Respiratory and other health hazards
Types of Engine Emission
Exhaust emission
Non exhaust emission
Exhaust emission
Unburnt hydrocarbons
Oxides of carbon
Oxides of notrogen
Oxides of sulphur
Particulates
Soot and smoke
Non-emission Emission
Fuel tank
Carburetor
Crankcase
Emission control methods
Thermal converters
Catalaytic converter
Exhaust gas recirculation (EGR)
Thermal converters
Thermal converters are high temperature chambers throug which the exhaust flows.
Promotione oxidation of the CO and HC which remain in the exaust.
CO + 1/2O2 CO2
Catalytic converter
Cataltic converters are chamders miunted in the flow system through which the exhaust gases pass through. These chmbers contain catalytic material which promotes the oxidation of emission contained in exhaust flow.
Types of catalytic converter
Two way converter
Three way converter
Three way converter
EGR
Most effective way of reducing NOx emission.
The Exhaust Gas Recirculation (EGR) system's purpose is to reduce NOx emissions that contribute to air pollution.
Why EGR?
Exhaust gas recirculation reduces the formation of NOX by allowing a small amount of exhaust gas to "leak" into the intake manifold.
The amount of gas leaked into the intake manifold is only about 6 to 10% of the total, but it's enough to dilute the air/fuel mixture just enough to have a "cooling effect" on combustion temperatures.
This keeps combustion temperatures below 1500 degrees C (2800 degrees F) to reduce the reaction between nitrogen and oxygen that forms NOx.
Working of EGR
To recirculate exhaust back into the intake manifold, a small calibrated "leak" or passageway is created between the intake and exhaust manifolds.
Intake vacuum in the intake manifold sucks exhaust back into the engine. But the amount of recirculation has to be closely controlled otherwise it can have the same effect on idle quality, engine performance and driveability as a huge vacuum leak.
Types of EGR valve
Ported EGR valves
Positive backpressure EGR valves
Negative backpressure EGR valves
Pulse-width modulated electronic EGR valves
Digital electronic EGR valves
Linear electronic EGR valves
COMMON EGR PROBLEMS
Pinging (spark knock or detonation) because the EGR system is not working, the exhaust port is plugged up with carbon, or the EGR valve has been disabled.
Rough idle or misfiring because the EGR valve is not closing and is leaking exhaust into the intake manifold.
Hard starting because the EGR valve is not closing and is creating a vacuum leak into the intake manifold.
Basic Emission Control Systems
Need of Emission Control System
Global warming
Acid rain
Smog
Odours
Respiratory and other health hazards
Types of Engine Emission
Exhaust emission
Non exhaust emission
Exhaust emission
Unburnt hydrocarbons
Oxides of carbon
Oxides of notrogen
Oxides of sulphur
Particulates
Soot and smoke
Non-emission Emission
Fuel tank
Carburetor
Crankcase
Emission control methods
Thermal converters
Catalaytic converter
Exhaust gas recirculation (EGR)
Thermal converters
Thermal converters are high temperature chambers throug which the exhaust flows.
Promotione oxidation of the CO and HC which remain in the exaust.
CO + 1/2O2 CO2
Catalytic converter
Cataltic converters are chamders miunted in the flow system through which the exhaust gases pass through. These chmbers contain catalytic material which promotes the oxidation of emission contained in exhaust flow.
Types of catalytic converter
Two way converter
Three way converter
Three way converter
EGR
Most effective way of reducing NOx emission.
The Exhaust Gas Recirculation (EGR) system's purpose is to reduce NOx emissions that contribute to air pollution.
Why EGR?
Exhaust gas recirculation reduces the formation of NOX by allowing a small amount of exhaust gas to "leak" into the intake manifold.
The amount of gas leaked into the intake manifold is only about 6 to 10% of the total, but it's enough to dilute the air/fuel mixture just enough to have a "cooling effect" on combustion temperatures.
This keeps combustion temperatures below 1500 degrees C (2800 degrees F) to reduce the reaction between nitrogen and oxygen that forms NOx.
Working of EGR
To recirculate exhaust back into the intake manifold, a small calibrated "leak" or passageway is created between the intake and exhaust manifolds.
Intake vacuum in the intake manifold sucks exhaust back into the engine. But the amount of recirculation has to be closely controlled otherwise it can have the same effect on idle quality, engine performance and driveability as a huge vacuum leak.
Types of EGR valve
Ported EGR valves
Positive backpressure EGR valves
Negative backpressure EGR valves
Pulse-width modulated electronic EGR valves
Digital electronic EGR valves
Linear electronic EGR valves
COMMON EGR PROBLEMS
Pinging (spark knock or detonation) because the EGR system is not working, the exhaust port is plugged up with carbon, or the EGR valve has been disabled.
Rough idle or misfiring because the EGR valve is not closing and is leaking exhaust into the intake manifold.
Hard starting because the EGR valve is not closing and is creating a vacuum leak into the intake manifold.
