Air Pollution & Vehicle Emissions
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Transcript of Air Pollution & Vehicle Emissions
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8/10/2019 Air Pollution & Vehicle Emissions
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AIR POLLUTION &
EVAPORATIVE EMISSIONS
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Hydrocarbons
Unburned fuel vapors
When exposed to sunlight, chemical
reaction occurs that producesground-level ozone O3.
Harmful to all living things
Vehicle emissions create 50% of thisozone
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Carbon Monoxide
Colorless, odorless, toxic gas
Product of incomplete combustion
Displaces oxygen which reducesoxygen in bloodstream
Vehicles produce 2/3s of co in
atmosphere
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Carbon Dioxide
Product of proper combustion
Does not directly impair human
health Greenhouse gas
Traps heat
Helping to increase global warming
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Just What is Ozone?
Ozone is a form of oxygen with adifferent chemical property
Ozone differs from oxygen: Has a distinctive odor Contains 3 oxygen atoms
Absorbs damaging ultraviolet (UV)
radiation
In large concentrations ozone ishazardous
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Earths Atmosphere
Troposphere start on the
surface and extends 59
miles
Air most dense
All weather occurs is
this region
Stratosphereextends for31 miles
Contains the Ozone layer
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Good Ozone
Blocks or absorbs most of the
suns ultraviolet rays
Approx. 3,000 million tons of
ozone in atmosphere
If concentrated at sea level,
would measure only 3 mm thick
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Bad Ozone (Smog)
Brown haze seen on hot summer days Result from burning fossil fuelschemical
reaction from heat & sun light
Health problems
Aggravates heart, lung ailments Can lower immune system
Eye & nose irritations
Environmental problems Inhibits plant growth, weakens plants
Reduce yields
Deteriorates man-made materials
Acid rain
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Evaporative EmissionsHydrocarbons escaping through fuel evaporation.
Diurnalgas evaporation as daytime
temps increase
Running Lossvaporization fromhot engine & exhaust parts
Hot Soakhot engines (off),
vaporization can continue RefuelingVapors forced out of tank
as liquid fuel enters
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Evap. Emission Control
Systems Sealed fuel tankdomed to allow for vaporexpansion
Liquid-vapor separatorwhen tank is full
fuel can enter vent lines Vent linesroutes vapor to canister &
engine
Activated charcoal canisterabsorbs fuelvapors, releases vapors with fresh air
Non venting gas cappressure/vacuumrelief valve
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Carbon Canister
Holds vapors when engine not running Engine fully warm & off idle, canister
is purged allowing fresh air in, fuel
vapors routed to engine & burned
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Canister Operation
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Purge Valve
Normally closed
Vacuum or electric solenoid
Engine off or idling valve is closed Engine running valve opens allowing
purge of canister
Solenoids either on/off or PWM
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Basic Purge Operation
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Thermostatic Vacuum
Switch (TVS)
Installed in intake manifold coolantpassage
Valve opens @ 115 F, allows vacuum to
flow
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Canister Venting
Open bottomWhen purging fresh
air enters from bottom of canister
Closed bottomfresh air enters forclean side of air filter
Electric vent solenoidPCM
controlled, allows fresh air in whencommanded, seals system when
closed.