1. Fall wk 3 – Mon.11.Oct.04 Welcome, roll, questions Thermal physics and Energy Ch.3 break continue Calculus Ch.1 Looking ahead Energy Systems, EJZ

2. Discuss Ch.3, Conventional conversion of energy Key points? Insights from team discussion? Questions? -questions of fact: Can we find answer in the text? What page? -Outstanding questions of fact -Outstanding significant questions

3. Energy conversion - outline Scientific principles – App.A Review of Thermal Physics New: Power and Efficiency Steam plant: closed cycle Engine cycles: open

4. Laws of Thermodynamics 0. Thermal equilibrium 1.Energy can be neither created nor destroyed. Ex: Heat in = Work done + internal energy 2. Entropy increases: useful energy is lost to heat

5. Heat = energy = work Energy = force * distance Joule = Newton * meter J = kg m 2 /s 2, cal = 4.1868 J = 4 x 10 -3 BTU Horsepower = 1 hp = 550 ft * lb/s = 746 Watt POWER = rate of doing work = Energy/time Watts = Joules/sec Efficiency = Energy in / Energy out = Power in / Power out Q: What is a kilowatt-hour? A measure of: A. Energy B. PowerC. Efficiency

6. Thermal energy  heat engine Steam power plant closed cycle, external combustion burn fossil fuel  heat water  steam  move turbines  electricity Gas and diesel engines open cycle, internal combustion compress  heat  ignite  expand  motion

7. Steam plant burn fuel  heat water  steam  move turbines  electricity Increase efficiency by decreasing losses

8. Generator: motion  electricity Electric Power = Voltage * Current: P = VI Ohm’s law: Voltage = Current * Resistance: V = IR Higher voltage transmission: lower ohmic losses

9. Engine cycles compress  heat  ignite  expand  motion Gas engines are usually less efficient than diesel engines

10. Work done by a gas (CT 3, 64, green) Work done = pressure * volume = area under curve (clockwise) Heat added = work done + change in internal energy of gas

11. How to improve engine performance? thermal efficiency is limited, since waste heat is exhausted compression ratio – diminishing returns, and higher temps  preignition * lower weight  better performance: a = F/m aerodynamics – small effect power train designs – gradual improvements * driving habits, mass transit

12. Calculus - outline Modified Calc HW Practice with logarithmic functions (Pre)Calculus question for seminar: If global energy use increases by 2.5% per year, how long will it take for global demand to double? a.First, guess. b.What is the percent increase if it doubles? c.Hint: D = D 0 a t

13. Calc 1 HW 2 Homework due this Thus: Calc 1 HW 2 without Ch.1.5 1.4 # 1, 2, 9, 11, 14, 18, 26, 35 1.6 # 2, 4, 14, 28 Next Thus: Calc 1 HW 3 1.5 # 1, 10, 14, 16, 20, 29, 31, 34, 36 1.6 # 8, 18, 23

14. Phys 18 HW 1 Thermal (and basic) physics problems due this Thus: Ch.1 #5, 7, 16, 18, 24, 26, 29 Ch.18 #4, 5, (24), 26, 28, 35, (73, 85) Problems in (parentheses) are not available on eGrade. Hand them in separately? I will post solutions after class Thus. Phys 18 HW 2 due next Thus: Ch.18 # (27), 29, 32, 33, (94)

15. Looking ahead Seminar in Sem II C2109 tonight Please put your team’s best Q on the board before 5:00 so we can start on time Tomorrow: –Debate: Coal vs Fission –visitors will discuss sustainability and solar panels on Tuesday and Wednesday Later: - TA available here Wed 1-3, QRC Fri 10-12 - Next Mon. CE Fair – we’ll set up telescope

16. Heat of transformation ConcepTests 80

17. Work done by gas ConcepTests

18. Steam plant cycle

19. Diesel engine cycle

20. Hydroplant