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Transportation

Explore the efficiency of transportation in the US, focusing on automobile engines, energy intensity, octane ratings, emissions control, and environmental impacts. Learn how cars work and impact the environment.

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Transportation

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  1. Transportation

  2. Automobiles in the US (1994) • 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 EGEE 102

  3. 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 EGEE 102

  4. Best website for information http://www.howstuffworks.com/engine.htm EGEE 102

  5. SI Engine Operation EGEE 102

  6. Parts of an Engine • Cylinder • Spark Plug • Valves • Piston • Piston Rings • Cooling system • Crankshaft EGEE 102

  7. Cylinder ArrangementV-6 Engine EGEE 102

  8. Cylinder Arrangement Inline Arrangement EGEE 102

  9. Cylinder Arrangement Flat Cylinder EGEE 102

  10. The Camshaft EGEE 102

  11. Engine Cooling System EGEE 102

  12. 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 4-cylinder 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." EGEE 102

  13. 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 EGEE 102

  14. Energy Intensity of Passenger Transport EGEE 102

  15. Energy Intensity of Freight Transport (Btu/ton-miles) EGEE 102 Source: http://www.eia.doe.gov/emeu/efficiency/eefig_ch5.htm#Figure%205.5

  16. 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 EGEE 102

  17. Gasoline: Octane Number • Octane has an octane rating of 100 • 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. For More info: http://www.howstuffworks.com/question90.htm EGEE 102

  18. Octane Number • Higher octane numbers are obtained by adding: • Branched chain hydrocarbons • Aromatics (now being reduced) • Antiknock agents EGEE 102

  19. Tubocharger EGEE 102

  20. 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 restriction in the exhaust EGEE 102

  21. Cars and Environment • See hand out EGEE 102

  22. 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

  23. Average Passenger Car Emissions EGEE 102

  24. 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)? EGEE 102

  25. 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 EGEE 102

  26. Sources of Emissions EGEE 102

  27. 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. EGEE 102

  28. 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 EGEE 102

  29. 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. EGEE 102

  30. Catalytic Converters EGEE 102

  31. 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. EGEE 102

  32. Honeycomb Structure EGEE 102

  33. 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. Catalyst Function EGEE 102

  34. 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 EGEE 102

  35. How to Help an Engine Produce More Power • 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 EGEE 102

  36. 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 EGEE 102

  37. Hybrid Cars Available http://www.eren.doe.gov/EE/transportation.html Honda Insight http://www.honda2001.com/insight/homepage.html Toyota Prius EGEE 102

  38. 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 chose a cleaner drive today. EGEE 102

  39. Cars of the Future • Hybrid cars • combines two or more sources of power. • Fuel Cells http://www.eren.doe.gov/EE/transportation.html EGEE 102

  40. Fuel Cells http://www.ott.doe.gov/pdfs/fuelcell_basics.pdf • 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 • ..\..\..\Desktop\Ami_320x240.ram EGEE 102

  41. Alternative Fuels • Methanol • Ethanol • CNG • Oxygenated Fuels • Reformulated Fuels More information on Clean Fuels: http://www.epa.gov/otaq/consumer/06-clean.pdf EGEE 102

  42. Two Stroke Engines • Lawn and garden equipment (chain saws, leaf blowers, trimmers) • Dirt bikes • Mopeds • Jet skis • Small outboard motors • Radio-controlled model planes EGEE 102

  43. 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. EGEE 102

  44. Two Strokes EGEE 102

  45. Disadvantages of Two Stroke Engines • Two-stroke engines don't last nearly as long as four-stroke 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 two-stroke 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. EGEE 102

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