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Energy, Gas Mileage and Hybrids

Energy, Gas Mileage and Hybrids. I love my Prius. Agenda. Energy Sources: Chemical, Nuclear, Mechanical, Hydro, Geothermal, Solar, … Energy Storage: Chemical, Mechanical, Thermal Energy in the Automobile: Efficiency, Losses and Gas Mileage The Hybrid Car and Gas Mileage. Energy Sources.

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Energy, Gas Mileage and Hybrids

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  1. Energy, Gas Mileage and Hybrids I love my Prius

  2. Agenda • Energy Sources: Chemical, Nuclear, Mechanical, Hydro, Geothermal, Solar, … • Energy Storage: Chemical, Mechanical, Thermal • Energy in the Automobile: Efficiency, Losses and Gas Mileage • The Hybrid Car and Gas Mileage J. N. Denenberg

  3. Energy Sources • Chemical • Nuclear: Fission, Fusion, radioactive decay • Hydro-Electric • Geothermal • Others • Solar • Wind • Tidal J. N. Denenberg

  4. Energy Sources: Chemical • Fossil Fuels • Petroleum • Coal • Renewable • Farm Plants • Wood • Waste: Bio/cooking • Algae http://web.mit.edu/erc/spotlights/alg-all.html http://www.valcent.net/i/misc/Vertigro/index.html • Primary Batteries • Limited Supply • Politics: No new US refineries in 30 years; Drilling bans • “Global Warming” • CO2: “a pollutant” • Plants: collect carbon • Fermentation: Ethanol • Squeeze/Filter: Fuel Oil • Limited sources J. N. Denenberg

  5. Energy Sources: Nuclear • Fission • Major source in some countries (France, 75%) • No new plants in 30 years in the US: Fear • Fusion: always 20 years away • Radioactive Decay Batteries: Use Google or seehttp://www.newscientist.com/article.ns?id=dn2951http://www.geekextreme.com/content/view/4344/7/ J. N. Denenberg

  6. Energy Sources: Hydroelectric • Good locations limited • Destroys valleys • Requires water supply • Dams have multiple uses; Conflict • Water supply : Farming, Urban • Flood Control • Power Generation J. N. Denenberg

  7. Energy Sources: Geothermal • “Free” energy • Limited readily available locations • Iceland: significant use • Yellowstone: Oops a national park • Heat mostly deep in the earth’s mantle J. N. Denenberg

  8. Energy Sources: Others • Solar Photovoltaic • Efficiency (10-20%) • Cost and surface area • Wind • Becoming practical where allowed • Noise, Scenic … • Tidal: actually under study see http://www.darvill.clara.net/altenerg/tidal.htm J. N. Denenberg

  9. Energy Storage • Rechargeable Batteries • Hydrogen • A storage-delivery mechanism • Not an energy source • Biofuels • Ethanol • Fuel Oil • Kinetic Energy: • Flywheels • Good portable temporary energy storage • Failure modes • Potential Energy: • Hydro revisited (not for cars) • Spring • Compressed air: see C.A.T.S. (limited range) J. N. Denenberg

  10. Storage: Rechargeable batteries • Lead Acid • NiCad, NiMh (Patent issues till 2015) • Lithium • Cons: Expensive, Fire-explosion • Usable example see (about 10 times lead-acid cost)http://www.valence.com/ J. N. Denenberg

  11. Energy and the Automobile • Energy source (fuel) • Engine energy utilization • The drive train • Air resistance • Rolling Resistance J. N. Denenberg

  12. Energy and the Automobile:Stored Energy (in the tank) • Need 300 mile range (a function of MPG) • Gasoline: 125,000 BTU/Gal • Ethanol: 80,000 BTU/Gal (that’s why our mileage/HP drops 3% with 10% Ethanol blend) • Diesel Oil: 139,000 BTU/Gal • LPG (Propane), LNG: 91,000 BTU/Gal (under pressure, up to 3,000 kPa) • Hydrogen: 52,000 BTU/lb (gasoline is 18,000 BTU/lb, To get gallons need high pressure) • Dry Wood: ~6,000 BTU/lb (Coal ~10,000 BTU/lb)(Included to discuss steam driven cars, 1 gal. wood weighs ~50 lb) J. N. Denenberg

  13. Energy Losses in Automobiles:The Engine • Efficiency • Gasoline: Up to 32% • Diesel: higher efficiency dueto more compression(also more BTU/gal) • Friction: Oil • Pumping Losses (Back Pressure) • Air filter (Up to 1% of peak engine HP when clean; Much more if dirty) • Exhaust System: Catalytic, Resonator, & Muffler (up to 20 % of peak engine HP; costs 10% MPG City, 4% MPG Highway) http://www.eere.energy.gov J. N. Denenberg http://www.swri.edu/

  14. Energy Losses in Automobiles:Drive Train • Manual: friction losses • Automatic (particularly the torque converter) J. N. Denenberg

  15. Energy Losses in Automobiles:Air Resistance • From Fluid Mechanics, Landau & Lifshitz • Cd: friction coefficient • A: effective frontal area (20-40ft2) • : Air density (.08 lb/ft3) • v: velocity • For a small car (A=20 ft2, Cd=.3) see: http://www.miata.net/sport/Physics/06-Speed.html J. N. Denenberg

  16. Energy Losses in Automobiles:Tires- Low Rolling Resistance • Limited availability • Silica (organosilanes ) replaces Carbon Black as the binder • Improves flexibility (low heat generation) • Improves traction • Reduces electrical conductivity (static buildup) • Soft sidewalls, Higher cost(Handling limitation – use higher air pressure) • Gas Savings of up to 10 % J. N. Denenberg

  17. Hybrid Cars:An Engineering Solution • Small Displacement Engine • Energy source using fuel • Low losses: size, maintained at efficient operating point • Atkinson/Miller cycle (Prius): (shorten intake/compression cycle)http://home.earthlink.net/~graham1/MyToyotaPrius/Understanding/InternalCombustion.htm • Ultra Low emissions: AT-PZEV • Better gas mileage / efficiency at best operating point • Poor low end torque (and lower peak HP) • Energy storage and recovery • Electric motor-generator to supply torque when needed • Battery to store energy that would have been wasted • CVT (Hybrid Synergy Drive – Prius) • Low losses • Smooth operation • Low engine stress • Software Control • Limit Engine RPM range • Limit batter stress • Maximize efficiency My Results • 2008 EPA Gas Mileage • 48 city • 45 highway • 46 combined • Actual Gas Mileage • 45.5 average mpg • ~43 winter • ~48 summer • up to 57 summer stop-go • 128k miles • 4.5 years J. N. Denenberg

  18. Toyota Prius • HEVAmerica Prius Test • Gasoline Engine • 1.5 Liter, 4-cylinder • Atkinson cycle, 78 HP • Electric Motor • 65 HP and second M-G to control HSD • Battery • 7.5 Amp-hour, 200 volt NiMh stack • Coolant Thermos • conserve heat for short period to avoid warm-up cycle (~32 mpg on short trips, engine runs continuously) J. N. Denenberg

  19. Toyota CVT: HSD • Low Friction Planetary gears (ball bearings) • 3 Rings • Outer: Electric Motor and drive shaft • Mid: Gasoline engine • Inner:Motor-Generator which controls the CVT see:HSD Simulator* *http://doctord.webhop.net/courses/bei/eg31/Lectures/Hybrid/ThsSimulator.jar J. N. Denenberg

  20. Actual Results J. N. Denenberg

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