7 traffic emission controls

8/12/2019 7 Traffic Emission Controls

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Traffic Emission Controls

Dr.Wesam Al Madhoun


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Emission Controls

Before beginning to understand emission

controls you should know the reason why

emission controls were installed into the

automobile.

1. To reduce the amount of pollutants entering the

atmosphere .


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Smog is a term developed from smoke.

Smog is form when airborne pollutants isformed with oxygen and other atmospheric

gasses to produce a grayish yellow smoke.

The resulting smoke is called photochemical

smog.


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Smog

Smog is can be a major problem in larger

cities (New York and LA)

Smog can be harmful to

A. Humans

B. Plants C. Animals and even effect paint rubber and

other materials.


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Smog

One of largest producer of photochemical

smog is the automotive internal combustion

engine.

The EPA (environmental protection agency)

begin putting restriction on automotivemanufactories in the mid 60.


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Motor Vehicle Emissions

Motor vehicle emission are emission

produce by motor vehicles. They include

A. Hydrocarbons (HC)

Carbon monoxide (CO)

Oxides of nitrogen (NOx)


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Exhaust Gasses

Hydrocarbons (HC) are emission of unburned

petroleum products being released into the

atmosphere.

All petroleum products and made of

hydrocarbons (hydrogen and carbon

compounds) this includes:

Gasoline LP-gas.

Diesel motor oil.


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Exhaust Gasses

Hydrocarbons are produced because ofincomplete fuel combustion or fuelevaporation.

Hydrocarbons emission is considered ahazardous form of air pollution because of.

Eye. Throat.

Lung irritation.

And possibility cancer.


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Exhaust Gasses

In the US a vehicle must not

exceed 220 ppm of

hydrocarbons emissions.

High hydrocarbon emission

are the results of a:

cylinder misfire.

Improper ignition timing

Pumping oil into the combustion

chamber


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Exhaust Gasses

Oxides of nitrogen, (NOx) are emission producedby extreme heat.

Air consist of approximately 79% nitrogen and 21%oxygen

When combustion chamber temperature reaches2500 degrees F or 1370 degrees C nitrogen andoxygen combine to produce oxide of nitrogen(NOx)


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In the US the standard for Carbon Monoxide

is 1.2 % of the total exhaust output.

Muffler

Exhaust output

HC 220 ppm

CO 1.2%


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Exhaust Gasses

The same factors that increases NOx will tend to

improve fuel mileage and lower HC and CO2

production.

This means that to increase fuel economy and

lower HC and CO2production NOx will increase.

For this reason emission controls have been added

to lower all form of emissions


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Exhaust Gasses

Fuel vapors: different chemicals that enter

the atmosphere as fuel evaporates.

Engine exhaust gasses: are harmful

chemical that are produced inside the

combustion chamber and are blow outer thetail pipe.


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Exhaust Gasses

Automotive manufactures agree the best

way to lower exhaust emission is to burn all

the fuel entering the combustion chamber.

Modern engine have introduced several

modification to ensure all fuel entering thecombustion chamber is burned.


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Some engine modification are:

Lower compression ratio, by lowering compression

ratio vehicle can burn unleaded fuel.

It is the ratio between the volume of

the cylinder and combustion chamber when

the piston is at the bottom of its stroke, and thevolume of the combustion chamber when the piston

is at the top of its stroke.

The use of unleaded fuel allows for catalytic

converters that help reduce HC and CO emissions.

Lower compression ratio also lower combustion

temperature reducing NOx emission.
http://en.wikipedia.org/wiki/Cylinder_(engine)http://en.wikipedia.org/wiki/Pistonhttp://en.wikipedia.org/wiki/Bottom_dead_centerhttp://en.wikipedia.org/wiki/Top_dead_centerhttp://en.wikipedia.org/wiki/Top_dead_centerhttp://en.wikipedia.org/wiki/Top_dead_centerhttp://en.wikipedia.org/wiki/Top_dead_centerhttp://en.wikipedia.org/wiki/Top_dead_centerhttp://en.wikipedia.org/wiki/Top_dead_centerhttp://en.wikipedia.org/wiki/Top_dead_centerhttp://en.wikipedia.org/wiki/Top_dead_centerhttp://en.wikipedia.org/wiki/Bottom_dead_centerhttp://en.wikipedia.org/wiki/Bottom_dead_centerhttp://en.wikipedia.org/wiki/Bottom_dead_centerhttp://en.wikipedia.org/wiki/Bottom_dead_centerhttp://en.wikipedia.org/wiki/Bottom_dead_centerhttp://en.wikipedia.org/wiki/Bottom_dead_centerhttp://en.wikipedia.org/wiki/Bottom_dead_centerhttp://en.wikipedia.org/wiki/Pistonhttp://en.wikipedia.org/wiki/Cylinder_(engine)


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Exhaust Gasses

Quench area


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Exhaust Gasses

Decrease valve overlap, is used to decrease

exhaust emission.

A larger valve overlap increases power but

dilutes incoming fuel mixture and requires a

richer air fuel mixture at lower engine speedtherefore increasing HC and CO emissions.


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Overlap

Intake Exhaust


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Wider spark plug gapThermostats arenow 190 degrees


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Vehicle Emission Control

There are several different types ofemission control system used on modern

vehicles.

Positive crankcase ventilation system(PCV) is used to re-circulate enginecrankcase fumes back into thecombustion chamber.

A PCV l if ld t d bl


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A PCV valve uses manifold vacuum to draw blow-

by gasses from the engine into the intake

manifold for re-burning by the engine.

In earlier years automotive manufactories uses

road draft tubes to remove crankcase blow by

gasses.


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The uses of road drift tube allowed for blow

by gasses containing HC, CO, particulates,

sulfur and small amounts of water to bevented in the atmosphere.

At idle when there is high engine vacuumthe PCV valve is opened to remove blow-by

gasses from inside the engine.


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When engine Vacuum is High PCV valve

plunger is nearly closed

When engine vacuum is low plunger Opens.

Allowing exhaust gasses into Engine.

PCV

Plunger

Typical PCV valve
http://www.partsamerica.com/product_images/AAP/PUR/Style355.jpg',%20'Purolator%20PV225


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Evaporative Emissions Control Systems

EVAP

The EVAP system prevents Hydrocarbons in theform of fuel vapors from entering the atmosphereeven when the vehicle is not running.

An EVAP system is considered a closed system.

Fuel vapor are stored in a charcoal canister whenthe engine is off.


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When the engine is started vacuum pulls fuel

vapors into the engine for burning.

EVAP system different from per emission vehicle

because no fuel or vapor is vented into the

atmosphere.


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Unvented Fuel Cap

Rollover Valve

Charcoal CanisterFuel Tank

IntakeManifold

Vacuum


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A rollover valve is uses to prevent fuel spillage in

case of a rollover.

A liquid-vapor separator is sometime used to

prevent liquid fuel from entering the charcoal

canister.

A charcoal canister is used to store fuel vapor when

the engine is not operating.

Exhaust Gas Recirculation System


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Exhaust Gas Recirculation System

(EGR)

An EGR system has two important jobs

1. The recirculation system is used to burn un-burns gasses(HC and CO) By recirculation of un-

burn gasses lower emissions can be achieved.

2.Lowering combustion chamber temperature. Bylowering combustion chamber temperature NOx

emission can be lowered.


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Exhaust Gasses

Exhaust Gasses to Engine

Vacuum

off

throttle

0 Vacuum Gauge


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EGR Valve Charcoal Canister
http://www.partsamerica.com/product_images/img/NIE/2-20028.jpg',%20'Niehoff%20Ignition%20FS4038


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Catalytic Converters

In the mid 70s automotive manufacture

begin installing catalytic converters to assist

in meeting tougher emission standards.

A Catalytic is a material that can speed-upchemical action without changing itself.


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Automotive catalytic converter are made of

platinum, palladium and rhodium or a

combination of these materials.

Platinum and palladium are used to change

HC and CO into CO2and Water.

Rhodium acts to reduce NOx emissions


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Due to enhance emissions standard, later

model catalytic converters now use ceriumto attract and release oxygen inside the

converter to aid in the process of changing

HC and CO to CO2and H2o


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The catalyst agent inside a catalytic converter is

either ceramic beds or a honeycomb-shaped blocks.

All catalytic converters are encased in a stainless

steel housing.

NOTE: stainless steel is used on newer vehicle with

catalytic converters because the production of water

will rust traditional exhaust system in only a few

years


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HC and COCO2 H2o

Catalytic Converter

Engine

Exhaust Flow from engine

through converter


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Stainless steel catalytic converter housing

are design to resist heat.

Before the catalytic converter can operate,

an operating temperature of around 300degrees F must be reached.


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This is a honey-comb block type catalytic

converter.

Exhaust gasses flow through the honey-comb

block

Th f diff t t t l ti


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There are a few different types catalytic

converters.

Monolithic Converter

Two way converter

Three way converter

Dual bed converter

Monolithic converter uses a ceramic honey-comb

catalytic


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Two way catalytic convertersonly convertHC and CO

With a two way converter NOx is notconverted

Two way converter are coated with platinumonly

Two way converter are sometime referred toas oxidation converters


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Three way catalytic converters can convert

all three exhaust gasses

HC

CO

NOx


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Dual bed catalytic converters must be at an

operating temperature of 130 degrees F

When the engine is cold additional air is

forced into the exhaust manifold to aid in theburning and reduction of HC and CO


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On a warn engine, air is forced into the converterto aid in burning exhaust gasses.

As exhaust gasses flows into the front part of theconverter, HC,CO and NOxis reduced.

As exhaust flow into the mixing chamber,additional air is added to continue the burningprocess.

Exhaust gasses passed into the rear part of theconverter to reduce HC,CO2and NOxever more.

7 traffic emission controls

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