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T c

T h. Q h. W. Q c. T c. a. Heat Engine Example. (a) - piston at. room temp and. atmospheric. pressure. P. V. (a-b) - gas. heated to keep. volume. b. constant as. cart rolls onto. piston. Heat Engine Example. P. a. V. c. Heat Engine Example. (b-c) - gas. heated to.

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T c

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  1. Th Qh W Qc Tc

  2. a Heat Engine Example (a) - piston at room temp and atmospheric pressure P V

  3. (a-b) - gas heated to keep volume b constant as cart rolls onto piston Heat Engine Example P a V

  4. c Heat Engine Example (b-c) - gas heated to increase b volume and lift P the cart a V

  5. (c-d) - gas cooled to keep volume constant at cart rolls off piston d Heat Engine Example c b P a V

  6. Heat Engine Example c b (d-a) - gas P cooled to reduce volume d back to initial a level V

  7. Work done?

  8. W, QH, QC, Efficiency, Power

  9. 1st Law Energy is conserved

  10. 2nd Law Impossible to convert heat completely to work i.e. no perfect heat engines

  11. DO DREAMS MATTER? Scott Adams: "Losers have goals, winners have systems." "Success caused passion more than passion caused success." vs. Nathan Pacheco: Give dreams you attention - they aren't going to burn brighter in the future.

  12. Carnot’s big idea A reversible engine works as well backwards as forwards . . . So no engine operating between two thermal reservoirscan have more efficiency than a reversible engine between the same reservoirs, and all reversible engines will have the same efficiency.

  13. Carnot cycle • Isothermal expansion • Adiabatic expansion • Isothermal compression • Adiabatic compression

  14. Carnot Efficiency

  15. Carnot engine Most efficient engine possible:

  16. These machines violate either Conservation of Energy 2nd Law of Thermodynamics What is wrong with this picture? Perpetual motion machines My first million $ Generator Battery

  17. Recycling heat from exhaust

  18. Otto Cycle

  19. COP Refrigerators and Heat Pumps

  20. Why gasoline? “Gasoline stinks. It pollutes the atmosphere with carbon dioxide, and it is blamed for global warming and for nitrous oxides that cause smog. It finances totalitarian dictatorships and terrorists and drives us to war.” – Richard Muller, Physics for Future Presidents

  21. What about Batteries? For the same weight : Gasoline has 100 times the usable energy of the best rechargeable batteries

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