AUTOMOTIVE EMISSION AND CONTROL

Emission ControlSOURCES 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 changeHelp 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 ControlExhaust 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 ControlHydrocarbons (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 EMISSIONSThe important exhaust emissions from a gasoline engine are: Carbon monoxide Unburnt hydroxide Nitrogen oxide Particulates

Exhaust GasesHC(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 injector3.Defective or worn ignition components: Ignition coil Spark plug wires. Timing off

Exhaust GasesOxides 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 SystemPCV (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 SystemAir 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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