Automobiles and the environment

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Lecture 6 Automobiles and the environment
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Environmental impacts

• Air pollution

Automobiles are responsible for a tremendous
amount of air pollution.
- The main source of CO and hydrocarbons
was Incomplete combustion of fuel. - Nitrogen
oxides were formed during combustion
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Example 1 Calculate the percentage reduction in
CO, HC, and NOx Exhaust emissions from a new
passenger car in 1997 Relative to an uncontrolled
car in 1967.
Grams per mile
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Despite these impressive reductions in new car
emissions, the air Quality impacts of automotive
emissions continue to be of concern, because of
1- Increasing vehicle population
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It is noticed that the total number of vehicles
on the road Continues to grow, more vehicles
caused more emissions
2- increasing travel per vehicle
3- Departures from federal standards
2. Greenhouse Gas emissions
Example 2 Annual CO2 emissions from cars.
Estimate the total annual Emissions of CO2 from
gasoline-burning vehicles in the united states
in 1995. the density of gasoline is 739 g/L. the
total gasoline Consumption by motor vehicles was
455109 liters/yr. we had 352 g CO2 Per 114 g of
fuel burned.
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3. Material Use and Solid Waste
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Example 3 Automobile solid waste, estimate the
total quantities of (a) recycled
materials (b) solid wastes from US
passenger car retirements in 1995. Based on 1995
data, assume that 95 of retired vehicles undergo
recycling and that 75 of each cars total
weight is recovered. Use the average weight of
1985 vehicles to estimate the per-vehicle Weight
of cars retired in 1995
(in millions)
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4. Other environmental impacts

• Lead emissions
• CFC emissions
• waste motor oil
• waste tires

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Energy efficiency
-the engine including all auxiliary system and
standby losses. -the drive-train includes
transmission, gear and drive wheels
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Example 4 Calculate the power needed to
maintain a speed of 25 m/s on a level highway
for a midsize car weighing 15000 N. The vehicle
has a cross-sectional area of 2 m2 and a drag
coefficient of 0.5. The coefficient of rolling
friction is 0.02, and the density of air is 1.2
kg/m3
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- Power for acceleration
Example 5 The car in previous example
accelerates from rest to 25 m/s in 10
seconds Calculate the average power required in
the absence of air Resistance and road friction.
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ENGINEERING CLEANER CARS
1- Designing For Energy Efficiency
2- understanding pollutant formation
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3- Designing For Low Emission
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Engine design is continually changing, mostly
driven by the demand for better fuel economy and
lower emissions. Small design changes such as
improved valve stem seals prevent lubrication
from entering the combustion chamber and exiting
the exhaust. Moving the top piston ring higher
on the piston helps reduce the crevices that
unburned fuel can "hide" in and reduces
hydrocarbon emissions. Improved cylinder bore
geometry stability allows the piston rings to
seal better and prevents oil from entering the
combustion chamber. New fuel injectors give
more consistent fuel spray patterns allowing for
more complete combustion of the fuel.
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4- Alternative Fuels
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Bioethanol - Bioethanol comes from plants and is
a renewable resource.
- Local emissions are up to 70 lower than
standard petrol or diesel cars
Biodiesel - Biodiesel is a renewable fuel that
is produced from the oil of crops
- It gives a 60 reduction
in C0²  
Hydrogen - Hydrogen fuel is produced from either
the breakdown of a
hydrocarbon source or by the electrolysis of
water.
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5- Alternative Vehicles
- Battery Power Electric Vehicles
Rechargeable batteries used in electric vehicles
include lead-acid, NiCd, nickel metal hydride,
lithium ion, Li-ion polymer
Electric vehicle in Malta
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Clever car has three wheels, holds half as many
passengers (two) than most cars do and manages
to emit less then half the CO2 emissions than
even the most efficient cars currently for sale.
The vehicle was designed at the Technical
University of Berlin