Exhaust System
Exhaust system components:
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1-Catalytic Converter
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2-Muffler
3-Resonator
4-Tail pipe
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Catalytic converter
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Came about in 1975.
It converts harmfull pollutants into less
harmful emissions .
The main emissions of acar engine
1-Nitrogen gas (N2 )
ِAir is 78-percent nitrogen gas .
2- Carbon dioxide (CO2)
This is aproduct of combustion, the carbon in the
fuel bonds with the oxygen in the air.
3-Water vapor ( H2O)
This id aproduct of combustion , the hydrogen in
the fuel bonds with the oxgen in the air.
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Catalytic converter are designed to reduce all three
1- carbon monoxide (co)
Is apoisonous gas that is colorless and odorless.
 2- Hydrocarbons or volatile organic
compounds (Vocs)
Are major component of smog .
 3- Nitrogen oxides (NO and NO2 called Nox)
Are a contributor to smog and acid rain.
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Catalytic converter structure
There are two different types of catalyst at work
1- a reduction catalyst .
2- and an oxidation catalyst .
Both types of aceramic structure coated with a
metal catalyst ,usually platinum , rhodium and
or palladium.
How catalytic converter work
A- The Reduction catalyst .
Is the first stage of the catalytic converter , it
usesplatinum and rhodium to help reduce the nox
emission.
 B-The oxidation catalyst
is the second stage of the catalytic converter. It reduces
the unburned hydrocarbons and carbon monoxide.
 C- Control system (O2 sensor )
that monitors the exhaust stream, and uses this
information to control the fuel injection system .
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The catalytic converter works
efficiently at afairly high temperature
We can reach this By :
 1- move the catalytic converter closer to the
engine .
 2- preheating the catalytic converter .
Catalytic converter in diesel engines
Do not work as well in reducing Nox.
2- Muffler
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Cancel out most of an engine’s noise .(sound
wave).
Where Does the sound come from ?
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Pulses are created when an exhaust valve
opens and a burst of high – pressure gas
suddenly enters the exhaust system.
How can you cancel out sounds?
If the first wave is at its maximum pressure ,
the second wave is at its minimum .
If both of these waves hit your ear drum , you
wouldnot hear anything.
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Inside a Muffler
Resonator
Common problems:
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1- corrosion… or more commonly known as
Rust
2- short trips .
3- oxygen sensor wearing .
4-The rust in the muffler .
5- the catalytic converter will become clogged.
References :
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http://auto.howstuffworks.com/turbo.htm
http://auto.howstuffworks.com/muffler.htm