AUTOMOTIVE EMISSION AND CONTROL

Emission Control
SOURCES OF VEHICLE EMISSONS
• Engine Crankcase Blow-by Fumes (20%)– heating oil
and burning of fuel that blows past piston rings and into
the crankcase.
• Fuel Vapour (20%) – chemicals that
enter the air as fuel evaporate.
• Engine Exhaust (60%)- blown out the tailpipe
when engine burns a hydrocarbon based fuel.

AUTOMOTIVE EMISSIONS

AUTOMOTIVE EMISSION:
Automotive emissions have following
sources:
Evaporative emission: it occurs when
there is escaping of fuel vapours into
the atmosphere from fuel tank and fuel
system.
Exhaust emission: release of exhaust
gases like HC,CO,NOX into the
environment after combustion of fuel.

Pollutants in Exhaust Gas
 Carbon monoxide(CO)
 Oxides of Nitrogen(Nox)
 Hydro Carbons(HC)
 Smoke and Soot
 Lead
 Sulphuric Oxide
 Particulate

Global Climate Change
• Gas and diesel burning vehicles also contribute to
global climate change.
• The Earth’s atmosphere acts like a blanket,
trapping some of the sun’s heat near the planet’s
surface. Without this natural insulation, the
average temperature on Earth would be -18°C
• Vehicle emissions also contain CO2, an important
Green house gas (GHG).
• If the atmosphere gets too thick with GHGs, too
much heat gets trapped. That can mean
problems for the whole world.

How Global Warming Works
Fossil fuels (coal, oil, natural gas)
Carbon Dioxide (CO2)

The Sun’s energy
passes through the
car’s windshield.
This energy (heat)
is trapped inside
the car and cannot
pass back through
the windshield,
causing the inside
of the car to warm
up.
Example of the
Greenhouse Effect

There are many actions individuals can do to reduce
fuel consumption of vehicle
 By saving fuel, these actions are good
for:
 Respiratory health
 Helping clean the air
 Fighting climate change
Help to reduce automotive emission

Speed limit
 Reduce your driving speed: The best fuel
economy for most vehicles is 90 km/h. Reducing
your speed from 100 km/h to 90 km/h improves
fuel economy by 10% and from 120 km/h to 90
km/h can save 23% on fuel consumption.
Avoid aggressive driving: Aggressive driving,
rapid acceleration, or quick stops has been shown
to increase fuel use by about 39%, and saves
about 4% of your time.

IDLING
Avoid idling:
• Excessive idling pollution
• Turn off the engine whenever you can.
• If you are stopped for more than ten seconds, turn it off
• . In the winter, the most effective way to warm up a cold
vehicle is to drive it. Idle for 30 seconds and then drive
away for optimum performance and fuel efficiency.

Regular tune-ups: A poorly tuned engine can consume an
average of 10% more fuel. One poorly tuned vehicle can emit
pollutants equivalent to 20 properly tuned vehicles.
Engine tune up

Engine tune up
Clean or replace air filters and
spark plugs:
Clean filters and spark plugs help keep
fuel use and greenhouse gas emissions
down.

Maintain braking systems: Dragging brakes can
decrease fuel efficiency by up to 40%.
Minimize air conditioner use: Using air conditioning can
increase fuel consumption and greenhouse gas emissions
by up to 21%.
Maintain wheel alignment: Make sure wheels are aligned
and balanced, and ball joints or constant velocity joints are
lubricated.
Other factors

 Use overdrive and high gears: While driving, strive for the
lowest engine rpm at a given road speed by selecting the
highest gear in which the vehicle will operate properly.
Operate overdrive automatic transmissions in the overdrive
mode.
Be aerodynamic: Reducing wind resistance on the highway
by rolling up the windows cuts fuel consumption.
Travel light: The heavier the
vehicle, the more fuel it burns.
Avoid unnecessary weight.
Other factors

Emission Control
Exhaust Emissions are produced by cars, buses, and
motorcycles.
Four basic types of exhaust emissions:
1.Hydrocarbons (HC)
2.Carbon monoxides (CO)
3.Oxides of nitrogen (NOx)
4.Particulates.

Emission Control
Hydrocarbons (HC)
• Resulting from the release of unburned fuel into the atmosphere.
●
Produced by incomplete combustion or by fuel evaporation.
• Effect could be eye, throat, and lung irritation, and, possibly cancer.
Carbon Monoxide (CO)
• Extremely toxic emission resulting from the release of partially
burned fuel (incomplete combustion of petroleum-based fuel).
• CO prevents human blood cells from carrying oxygen to body tissue.
• Symptoms are headaches, nausea, blurred vision, and fatigue.
• A rich air-fuel would increase CO; lean air-fuel mixture would lower
CO emissions.
• Mostly related to ignition problems.

EXHAUST EMISSIONS
The important exhaust emissions from a
gasoline engine are:
 Carbon monoxide
 Unburnt hydroxide
 Nitrogen oxide
 Particulates

Exhaust Gases
HC(HYDROCARBON) :
Produced by unburnt fuel.
CAUSES OF HC:
1.Rich air fuel mixture:
 Defective O2 sensor
 Leaky fuel injector
 Clogged air filter.
2.Very lean air fuel mixture:
 Clogged fuel pump , fuel filter and fuel injector
3.Defective or worn ignition components:
 Ignition coil
 Spark plug wires.
 Timing off

Exhaust Gases
Oxides of Nitrogen (NOx)
●
Produced by extremely high
temperatures during
combustion.Cooling system issues.
Lean air fuel mixture.
Poor catalytic convertor.
Over advanced timing.
• An engine with high compression ratio, lean air-fuel mixture, and
high-temperature thermostat will produce high combustion heat,
resulting in formation of NOx.

Exhaust Gases
CO:
Carbon monoxide emission are exhaust emission that
is the result of partially burned fuel or products of
incomplete combustion.
A high carbon monoxide emission can be caused by :
 Restricted or dirty air cleaner.
Advance ignition timing.
Clogged fuel injectors.
Rich air fuel mixture.
Defective or worn out ignition components.

Exhaust Gases
14.7 – 1 AFRRicher Leaner
HC increases
NOx decreases
NOx
increases
Hc and Co
decreases

CATALYTIC CONVERTOR

Method to reduce
exhaust emission
Catalytic converter
 Exhaust gas pass from exhaust
manifold to catalytic convertor
through pipe.
 Due to partial combustion , gases
entering inside catalytic converter
consists of CO,HC,NOX.
 Inside calalytic converter consists of
ceramic blocks of platinum and
rhodium acting as catalyst.

REACTIONS:
 Gas enters inside catalyst causes the
oxides of nitrogen to reform into nitrogen
and oxide.
 NOX O2 + N2
Carbon monoxide reacts with oxygen
molecules to form CO2.
2CO+O2 2CO2
The unburnt hydrocarbons react with oxygen
and carbon dioxide.
HC+ O2 H2O+CO2
FINALLY THE EXHAUST GASES CONSISTING
OF LESS HARMFUL GASES .

Catalytic Converter

Emission Control System
• At idle, high manifold vacuum pulls the
plunger
for minimum vapour flow (prevents a lean air-
fuel mixture).
• During acceleration, intake manifold
decreases. This allows the PCV valve to
move to a center position for maximum
flow.
• With engine off, a spring pushes the valve
against its seat, closing the valve. A
backfire will also close the valve.
PCV (Positive Crankcase Ventilation System)

Vehicle Emission Control System
PCV (Positive Crankcase Ventilation System)
• Uses engine vacuum to draw blow-by gases into the intake manifold
for
reburning in the combustion chamber.
• Vacuum or electronic controlled, mounted on the valve cover.

Vehicle Emission Control System
Air Injection System
• Forces fresh air into the exhaust ports or catalytic converter to reduce HC/CO.
• Oxygen from the air injection system causes the unburned fuel to burn in the
exhaust system or the catalytic converter.

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