Description of the Exhaust system along with its components such as Exhaust manifold,catalytic converter ,muffler ,exhaust tubing and oxygen sensor.The working of some of these components is also explained.
By: Shah Shivank Kirit (1115100)
Siddhanth Shetty (1115101)
• An exhaust system is usually piping used to guide
reaction exhaust gases away from a controlled combustion inside an
engine or stove. The entire system conveys burnt gases from the engine
and includes one or more exhaust pipes.
• Keeping the exhaust system in good working condition is vital for fuel
mileage, the environment and your safety.
The exhaust manifold attaches to the cylinder head and takes
each cylinders exhaust and combines it into one pipe. The
manifold can be made of steel, aluminum, stainless steel, or more
commonly cast iron.
Exhaust Pipe :
• Between all of the parts is the exhaust pipe which carries the gas
through it's journey out your tail pipe.
• Exhaust tubing is usually made of steel but can be stainless steel
(which lasts longer due to it's corrosion resistance) or aluminized
steel tubing. Aluminized steel has better corrosion resistance than
plain steel but not better than stainless steel. It is however cheaper
than stainless steel.
Main Parts :
Oxygen Sensor :
All modern fuel injected cars utilize an oxygen sensor to
measure how much oxygen is present in the exhaust. From this the
computer can add or subtract fuel to obtain the correct mixture for
maximum fuel economy. The oxygen sensor is mounted in the
exhaust manifold or close to it in the exhaust pipe.
How does Oxygen Sensor Work?
The oxygen sensor is positioned in the exhaust pipe
and can detect rich and lean mixtures.
The mechanism in most sensors involves a chemical
reaction that generates a voltage.
The engine's computer looks at the voltage to
determine if the mixture is rich or lean, and adjusts
the amount of fuel entering the engine accordingly.
This muffler like part converts harmful carbon monoxide and
hydrocarbons to water vapor and carbon dioxide. Some converters
also reduce harmful nitrogen oxides. The converter is mounted
between the exhaust manifold and the muffler.
Construction of Catalytic Convertor
In the catalytic converter, there are two different types of catalyst at
work, a reduction catalyst and anoxidation catalyst. Both types
consist of a ceramic structure coated with a metal catalyst, usually
platinum, rhodium and/or palladium.
The idea is to create a structure that exposes the maximum surface
area of catalyst to the exhaust stream, while also minimizing the
amount of catalyst required, as the materials are extremely expensive.
Working of a catalytic converter:
Most modern cars are equipped with three-way catalytic converters.
The reduction catalyst is the first stage of the catalytic converter. It
uses platinum and rhodium to help reduce the NOx emissions.
2NO => N2 + O2 .
• The oxidation catalyst is the second stage of the catalytic converter.
It reduces the unburned hydrocarbons and carbon monoxide by
burning (oxidizing) them over a platinum and palladium catalyst.
2CO + O2 => 2CO2
• In the final stage hydrocarbons combine with oxygen to form water and
The muffler serves to quiet the exhaust down to acceptable levels.
Remember that the combustion process is a series of explosions
that create allot of noise. Most mufflers use baffles to bounce the
exhaust around dissipating the energy and quieting the noise.
Some mufflers also use fiberglass packing which absorbs the sound
energy as the gases flow through.