In response to an increasing push for clean diesel emissions, medium and heavy duty diesel-powered trucks have adopted complex exhaust or emission aftertreatment systems. These systems treat post-combustion gases after they leave the engine, reducing environmental impact without sacrificing power or performance.

1. SHIVLEELA S. ANGADI
ADAM CENTRE, PUNE
12/03/2019
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• When engine is running and when process
reaches at its last stage, it pass number of
harmful substance through exhaust valve.
Like NO, CO, NOx and many more.
• If these substance directly release to the
atmosphere it will be harmful for all humans
and can create other problem like global
warming.
• Gases coming out after exhaust stroke are
harmful in many ways.
Fig. 1: Combustion process
Source : www. Google.com/Combustion-process

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 These harmful gases contains:
1. Carbon monoxide (CO) is a poisonous gas that is colorless and odorless.
2. Hydrocarbons or volatile organic compounds (VOCs) are a major component
of smog produced mostly from evaporated, unburned fuel.
3. Nitrogen oxides (NO and NO2, together called NOx) are a contributor to smog
and acid rain, which also causes irritation to human mucus membranes.
 To avoid this catalytic converter is used which convert the harmful gases into
harmless.
Fig. 2: Exhaust Process
Source : www. Google.com/ Exhaust Process- Animation

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• A catalytic converter is an exhaust emission control device
that converts toxic gases and pollutants in exhaust gas from
an internal combustion engine into less-toxic pollutants.
• The extreme heat in the converter oxidizes the exhaust
that flows out of the engine .
• As a part of exhaust system catalytic converter has two
roles:
1. As emission control device – responsible for converting
undesirable exhaust gases into harmless gases.
2. Helps reduce noise level of exhaust system.
• Catalytic converters are also used on electrical generators,
forklifts, mining equipment, trucks, buses, locomotives, and
motorcycles. They are also used on some wood stoves to
control emissions.
Fig. 3: Diagramatic representation of Catalytic
converter
Source : www. Google.com/catalytic-converter

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• This device is installed in the exhaust system between the
exhaust manifold and the muffler, and usually is positioned
beneath the passenger compartment.
Fig. 4: Location of Catalytic converter
Source : www. Google.com/Location-of-catalytic-converter

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Fig. 5: Construction of Catalytic converter
Source : www. Google.com/construction-of-catalytic-converter
• An internal combustion engine creates
heat energy by igniting a mixture of
gasoline and atmospheric oxygen with a
high-voltage spark.
• Unfortunately, a residual quantity of
hydrocarbons (HC), carbon monoxide (CO),
and nitrogen oxides (NOX) are left over
after combustion.
• Consequently, a catalytic converter uses
precious metals like platinum as a catalyst
to convert harmful pollutants like HC, CO
and NOX into harmless gases like oxygen
(O2), carbon dioxide (CO2) and water
(H2O).

7. • Since a catalyst will accelerate a chemical reaction without being consumed by
the process itself, the catalytic convertor will theoretically last forever.
• In reality, catalytic converters eventually succumb to contaminants from coolant
and engine oil additives and heat stress.
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Fig. 6: Location of Catalytic converter
Source : www. Google.com/Location-of-catalytic-converter

8. 1. Two-Way Catalytic Converter
2. Three-Way Catalytic Converter
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Fig. 7: Two way Catalytic converter
Source : www. Google.com/Two-way-catalytic-converter
Fig. 8: Three way Catalytic converter
Source : www. Google.com/Three-way-catalytic-converter

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• It is widely used on diesel engines to reduce hydrocarbon and carbon monoxide emissions, and
they were also used on spark ignition (gasoline) engines.
• Two-way catalytic converter performs two simultaneous tasks of oxidation of carbon monoxide of
hydrocarbons to carbon dioxide and water.
• The first stage helps in reducing the amount of carbon monoxide emissions. In second stage
hydrocarbons created by unburned fuel oxidizes to form carbon dioxide and water.
Fig. 9: Two way Catalytic converter
Source : www. Google.com/Two-way-catalytic-converter

10.  A two-way catalytic converter has two simultaneous tasks:
1. Oxidation of carbon monoxide to carbon dioxide:
2. Oxidation of un-burnt and partially-burnt hydrocarbons to
carbon dioxide and water:
 Disadvantage : Inability to control oxides of nitrogen
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2 CO + O2 → 2 CO2
CxH2x+2 + [(3x+1)/2] O2 → x CO2 + (x+1) H2O (a combustion reaction)

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Fig. 10: Three way Catalytic converter
Source : www. Google.com/Three-way-catalytic-converter
 Similar to the oxidation converter, the
reduction catalytic converter helps to
eliminate hydrocarbons and carbon-
monoxide emanations, in addition to
oxides of nitrogen discharges, or NOx.
 NOx outflows are created in the motor
burning chamber when it reaches
extremely high temperatures more than
2,500 degrees Fahrenheit, approximately.
 The two processes that takes place in a
Three way catalytic converter are:
1. Reduction Catalyst
2. Oxidation Catalyst

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1. Reduction of nitrogen oxides to nitrogen and oxygen:
2. Oxidation of carbon monoxide to carbon dioxide:
3. Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water:
2NOx → xO2 + N2
2CO + O2 → 2CO2
CxH(2x+2) + [(3x+1)/2]O2 → xCO2 + (x+1)H2O
Three-way catalytic converter -
how does it work.mp4
Fig. 2: Three way Catalytic converter
Source : www. Google.com/Three-way-catalytic-converter-gif

13. 13Fig. 12: Emission standard limits
Source : www. Google.com/emission-from-diesel-engine

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0.180 0.230
0.080 0.170
0.080 0.170
1. CO = Carbon Monoxide
2. THC = Hydrocarbons
3. NMHC = Volatile Organic Compounds
4. Nox = Nitrogen oxides
5. HC+NOx
6. PM = Particulate Matter
7. PN = Particle Number of
thermodynamic system
0.50 0.560
0.25 0.30
0.180 0.230
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 In response to an increasing push for clean diesel emissions, medium and heavy duty
diesel-powered trucks have adopted complex exhaust or emission aftertreatment systems.
 These systems treat post-combustion gases after they leave the engine, reducing
environmental impact without sacrificing power or performance.
 The primary components of a vehicle’s aftertreatment
system are :
1. Diesel Oxidation Catalyst (DOC) -
reduces particulate matter and oxidizes
carbon monoxide and hydrocarbons.
2. Diesel Particulate Filter (DPF) - This filter
is designed to remove more than 90% of
particulates out of the exhaust.
3. Selective Catalytic Reduction System (SCR) -
which reduces nitrogen oxide (NOx) into N2
Fig. 13: Catalytic converter
Source : www. Google.com/catalytic-converter

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DOC DPF SCR
D
E
F
Exhaust gases leave engine
Oxidation of CO and HC
Particulates(PM) trapped in
diesel particulate filter
DEF injected into exhaust
NOx reduction in SCR
Reduced volume of emission
leaves tailpipe.
PM and NOx near zero levels.
Fig. 14: Process of diesel emission control system

17.  Diesel Oxidation Catalyst (DOC) is specially designed
for diesel engine.
 A Diesel Oxidation Catalyst (DOC) is an
aftertreatment component that is designed to convert
carbon monoxide (CO) and hydrocarbons (HC) into
carbon dioxide (CO2) and water(H2O).
 DOC’s are maintenance free, inexpensive and simple
in construction and are suitable for all types of diesel
engines.
 The exhaust coming from the engine first passes
through the DOC.
 It is mainly used for oxidizing nitrogen monoxide
(NO) to nitrogen dioxide (NO2), substances that
together create NOx.
 However, the DOC also has another important
function, which is related to regeneration of the DPF.
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Fig. 15 Diesel oxidation catalyst
Source : www. Google.com/ Diesel-oxidation-catalyst

18.  The DPF comes after the DOC in the exhaust aftertreatment system.
 The DPF removes most of the soot particles (more than 99 %) from the exhaust gases.
 The exhaust gases pass through the filter, which collects particles from the gases. The
particles eventually turn into a soot cake. The increasing amount of soot will create a
high pressure in the DPF, which means the soot needs to be removed. This can be done
either by stand still regeneration or passive/moving regeneration
18Fig. 16: Diesel Particulate Filter
Source : www. Diesel Particulate Filter

19.  Filters are made up of porous, catalytically coated silicon carbide material
that traps exhaust particulates.
 Diesel particulate filters operate by trapping soot particles from the engine
exhaust, preventing them from reaching the environment.
 The DOC and DPF work at the front end of the system to reduce carbon
monoxide and hydrocarbons, but more importantly, capture soot and ash in
the exhaust system to reduce the risk of those particles reaching the
atmosphere.
19Fig. 17: Working of Diesel Particulate Filter
Source : www. Google.com/ Diesel Particulate-Filter-working

20.  Completely eliminates exhaust smoke even
though sudden acceleration and rapid
driving changes.
 The particulate filter is designed to trap
and retain the solid particles until the
particles can be oxidized or burned in the
DPF itself, through a process called
regeneration.
 There are three different types of
regeneration:
 Stand Still Regeneration
 Moving Regeneration
 Passive Regeneration
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Fig. 18: Diesel Particulate Filter
Source : www. Google.com/ Diesel Particulate Filter

21.  Selective Catalytic Reduction (SCR) is an
advanced active emissions control technology
system that injects a liquid-reductant agent
through a special catalyst into the exhaust
stream of a diesel engine.
 The reductant source is usually automotive-
grade urea, otherwise known as Diesel
Exhaust Fluid (DEF) or AdBlue.
• Reduces levels of NOx using ammonia as a
reductant within a catalyst system.
• The chemical reaction is known as
"reduction" where the DEF is the reducing
agent that reacts with NOx to convert the
pollutants into nitrogen, water and tiny
amounts of CO2.
• SCR technology alone can achieve NOx
reductions up to 90 percent.
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Fig. 19: Selective catalytic reduction
Source : www. Google.com/Selective-catalytic-reduction

22. 22Exhaust gas treatment for passenger cars and light commercial vehicles - Denoxtronic.mp4
Fig. 21: Selective catalytic reduction
Source : www. Google.com/Selective catalytic reduction
Fig. 20: Selective catalytic reduction
Source : www. Google.com/Selective catalytic reduction

23.  Diesel exhaust fluid (DEF) is an aqueous urea solution made with 32.5% urea and
67.5% deionized water which is injected on the exhaust gases coming out of DPF.
 AdBlue was invented by the German Association of the automobile industry (VDA)
 The DEF sets off a chemical reaction that converts nitrogen oxides into nitrogen, water and
tiny amounts of carbon dioxide (CO2), natural components of the air we breathe, which is
then expelled through the vehicle tailpipe.
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Fig. 22: Diesel exhaust fluid(DEF)/AdBlue
Source : www. Google.com/Diesel-exhaust-fluid

24.  When the fluid gets hot, the water evaporates and the urea converts to ammonia.
The ammonia reacts with a special catalyst in the SCR muffler and converts the
NOx to nitrogen and water.
 AdBlue has different names in different countries such as, outside of Europe
as DEF, ARLA 32 or AUS 32 in some countries
 Amount of AdBlue injected is dependent on the speed and the load of the engine.
 AdBlue should be kept in the optimal conditions — out of direct sunlight and at a
temperature between -6°C and 25°C — your AdBlue can last up to 18 months in
storage.
 AdBlue is not flammable, nor is it considered a hazardous liquid. It is a water-
based urea solution, and poses little risk to humans. If you have sensitive skin, it
might be wise to wear gloves when handling the liquid to avoid any potential
irritation.
24Fig. 23: Diesel exhaust fluid(DEF)/AdBlue
Source : www. Google.com/Diesel-exhaust-fluid

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Mercedes-Benz AdBlue Technology.mp4
Fig. 24: Reaction Diesel exhaust fluid
Source : www. Google.com/Diesel exhaust fluid

26. 1. Is AdBlue a toxic solution?
2. Is the 32.5% urea solution critical?
3. What is the freeze point of AdBlue?
4. With a freezing temperature of -11 deg C, what happens to the operation of the
vehicle if the AdBlue freezes?
5. Will there be special equipment to ensure the AdBlue does not freeze, or can be
thawed if it does freeze?
6. Is AdBlue corrosive?
7. If AdBlue is corrosive to aluminium, what will the AdBlue tanks be made of?
8. How much AdBlue will a vehicle consume?
9. Testing of Diesel Exhaust Fluid Diesel Exhaust Fluid Testing.mp4
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27.  Exhaust gas aftertreatment – explained in a simple way!.mp4
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