EGEE 102 – Energy Conservation
And Environmental Protection
Transportation
Automobiles in the US
(1994)
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156 Million Vehicles
11,400 miles average miles/y
578 gallons of gasoline
19.8 mpg
88.3 billion gal of gasoline
1.2 billion gal of Diesel
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How Cars Work?
• Almost all cars currently use what is called a
four-stroke combustion cycle to convert
gasoline into motion. The four-stroke
approach is also known as the Otto cycle, in
honor of Nikolaus Otto, who invented it in
1867. The four strokes are
• The intake stroke.
• The compression stroke.
• The combustion stroke
• The exhaust stroke
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Best website for
information
http://www.howstuffworks.com/engine.htm
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SI Engine Operation
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Parts of an Engine
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Cylinder
Spark Plug
Valves
Piston
Piston Rings
Cooling system
Crankshaft
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Cylinder Arrangement
V-6 Engine
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Cylinder Arrangement
Inline Arrangement
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Cylinder Arrangement
Flat Cylinder
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The Camshaft
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Engine Cooling System
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Compression Ratio
The difference between the maximum and minimum is
called the displacement and is measured in liters or
CCs (Cubic Centimeters, where 1,000 cubic
centimeters equals a liter). So if you have a 4cylinder engine and each cylinder displaces half a
liter, then the entire engine is a "2.0 liter engine." If
each cylinder displaces half a liter and there are six
cylinders arranged in a V configuration, you have a
"3.0 liter V-6."
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Efficiency
• When the United States recognized the hazards of its
dependency on foreign oil supplies in the aftermath of
the first oil embargo in 1973, passenger automobile
fuel economy averaged only 14 miles per gallon
(mpg).
• Congress established Corporate Average Fuel
Economy (CAFE) standards in 1975 for each
automaker, with domestically produced and imported
automobiles counted as separate fleets.The uniform
CAFE standard for automobiles began at 18 mpg
with the 1978 model year, increasing to 27.5 mpg by
1985
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Energy Intensity of
Passenger Transport
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Energy Intensity of
Freight Transport
(Btu/ton-miles)
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Source: http://www.eia.doe.gov/emeu/efficiency/eefig_ch5.htm#Figure%205.5
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Efficiency of a IC Engne
• As the compression ratio increases efficiency
increases
• As the compression ratio increases, fuel
quality (Octane number) is important
• Higher compression ratios produce more
power, up to a point. The more you compress
the air/fuel mixture, however, the more likely it
is to spontaneously burst into flame (before
the spark plug ignites it). Higher octane
gasoline prevents this sort of early
combustion
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Gasoline: Octane
Number
1. Octane has an octane rating of 100
2. Heptane has an octane rating of 0
Gasoline is compared in a test engine
with a mixture of heptane and “octane.”
The higher the “octane” number the less
likely to knock.
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For More info: http://www.howstuffworks.com/question90.htm
Octane Number
Higher octane numbers are obtained by
adding:
1. Branched chain hydrocarbons
2. Aromatics (now being reduced)
3. Antiknock agents
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Tubocharger
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Where the turbocharger is
located in the car
• Power is determined
by the amount of air
and fuel that it can
burn.
• The typical boost
provided by a
turbocharger is 6 to
8 pounds per square
inch (PSI).
• Increased restriction20
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in the exhaust
Cars and Environment
• See hand out
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Automobile Emissions
• Hydrocarbons (Paraffins, Olefins,
Naphthenes, Aromatics)
• Nitrogen Oxides (NO, NOx, NO2)
• Carbon Dioxide (CO2)
• Carbon Monoxide (CO)
• Particulates (any material collected
on a filtering medium after exhaust
dilution)
• Air Toxics (???)EGEE 102
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Average Passenger Car
Emissions
Pollutant
Hydrocarbons
Emission Rate
(g/mile)
2.8
Carbon
20.9
Monoxide
Nitrogen Oxides 1.39
CO2
0.916 lb
Gasoline
0.0465 gal
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Personal Auto Emissions
• Calculate the annual emissions (lbs)
by your car based on the average
annual mileage and the kind of car
you you (mpg)?
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Effect of Carpooling
• Average commute is 20 miles round
trip.
• 1,000 people participate in the
carpool program.
• Calculate the personal monetary
savings annually and the reduction
of emissions (lbs) based on the
emissions per mile
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Sources of Emissions
Source
Exhaust
Crankcase
emission
Fuel Tank
Evaporation
Carburetor
evaporation
Pollutant %
CO HC
NOx Particles
100 62
100 90
20
10
9
9
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Processes by Which
Gasoline Compounds
Escape Burning
• Gasoline vapor-air mixture
compressed into the combustion
chamber crevice volumes
• Gasoline compounds absorbed in oil
layers on the cylinder liner
• Gasoline absorbed by, and/or
contained within, deposits on the
cylinder head and piston crown.
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Parameters that
Influence Emissions
from Gasoline Engines
• Carburetion and Fuel Injection
• Spark timing
• Surface to volume ratio, valve timing
and the use of exhaust gas
recirculation
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Environmental Problems
• The pollution comes from two sources. The
first is the combustion of the oil. The oil
makes all two-stroke engines smoky to some
extent, and a badly worn two-stroke engine
can emit huge clouds of oily smoke.
• Each time a new charge of air/fuel is loaded
into the combustion chamber, part of it leaks
out through the exhaust port. That's why you
see a sheen of oil around any two-stroke boat
motor.
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Catalytic Converters
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Pollution Reduction
• A three-way catalytic
converter - Both types
consist of a ceramic
structure coated with
a metal catalyst,
usually platinum,
rhodium and/or
palladium. two
separate catalysts.
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Honeycomb Structure
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Catalyst Function
• The reduction
catalyst is the first
stage of the catalytic
converter. It uses
platinum and
rhodium to help
reduce the NOx
emissions.
• The oxidation catalyst
is the second stage of
the catalytic converter.
It reduces the unburned
hydrocarbons and
carbon monoxide by
burning (oxidizing) them
over a platinum and
palladium catalyst.
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What You Can do to
Save the Environment
• See the Handout (Your Car and
Clean Air)
• Avoid Unnecessary Driving
• Maintain your car properly
• Drive your car wisely
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How to Help an Engine
Produce More Power
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Increase displacement
Increase the compression ratio
Stuff more into each cylinder
Cool the incoming air
Let air come in more easily
Let exhaust exit more easily
Make everything lighter
Inject the fuel
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Hybrid Technology
Efficiency
• Recover energy and store it in the
battery
• Sometimes shut off the engine
• Use advanced aerodynamics to
reduce drag
• Use low-rolling resistance tires
• Use lightweight materials
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Hybrid Cars Available
http://www.eren.doe.gov/EE/transportation.html
Honda Insight
http://www.honda2001.com/insight/homepage.html
Toyota Prius
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HEVs
• The HEV is able to operate
approximately two times more
efficiently than conventional vehicles.
Honda's Insight can go 700 miles on a
single tank of gas. The Toyota Prius can
go about 500 miles. For the driver,
hybrids offer similar or better
performance than conventional
vehicles. More important, because such
performance is available now, hybrids
are a practical way for consumers to
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chose a cleaner drive
today.
Cars of the Future
• Hybrid cars
• combines two or
more sources of
power.
• Fuel Cells
http://www.eren.doe.gov/EE/transportation.html
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http://www.ott.doe.gov/pdfs/fuelcell_basics.pdf
Fuel Cells
• Based on an electrochemical reaction
that combines hydrogen with ambient
air
• Pure hydrogen or any fossil fuel that
has been "reformed" can be used to
produce a hydrogen-rich gas
• Fuel cell's emission is mostly water
vapor
• Energy conversion efficiencies up to
50% are demonstrated
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Alternative Fuels
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Methanol
Ethanol
CNG
Oxygenated Fuels
Reformulated Fuels
More information on Clean Fuels:
http://www.epa.gov/otaq/consumer/06-clean.pdf
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Two Stroke Engines
• Lawn and garden equipment (chain
saws, leaf blowers, trimmers)
• Dirt bikes
• Mopeds
• Jet skis
• Small outboard motors
• Radio-controlled model planes
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2 Stroke Engine
• Two-stroke engines do
not have valves, which
simplifies their
construction.
• Two-stroke engines fire
once every revolution
(four-stroke engines fire
once every other
revolution) -- this gives
two-stroke engines a
significant power boost.
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Two Strokes
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Disadvantages of Two
Stroke Engines
• Two-stroke engines don't last nearly as long as fourstroke engines. The lack of a dedicated lubrication
system means that the parts of a two-stroke engine
wear a lot faster.
• Two-stroke oil is expensive, and you need about 4
ounces of it per gallon of gas. You would burn about
a gallon of oil every 1,000 miles if you used a twostroke engine in a car.
• Two-stroke engines do not use fuel efficiently, so you
would get fewer miles per gallon.
• Two-stroke engines produce a lot of pollution. So
much, in fact, that it is likely that you won't see them
around too much longer.
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