1. Chapter 4 Engines and Refrigerators

2. Heat Engine QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine

3. Heat Engine QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine

4. Heat Engine QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine 1.Bring in or create heat 2.Convert some heat to work 3.Dump unused heat 4.Repeat

5. Carnot Cycle – Most Efficiency The production of motive power is therefore due in steam engines not to actual consumption of caloric but to its transportation from a warm body to a cold body. In the fall of caloric, motive power evidently increases with the difference of temperature between the warm and cold bodies, but we do not know whether it is proportional to this difference. Sadi Carnot 1796 - 1832

6. Timeline 1824 –Sadi Carnot identified heat engine and based it on 1 st and 2 nd laws 1848 –Absolute temperature scale (Kelvin) 1865 –Clausius defined the Carnot cycle mathematically and introduced entropy 1877 –Boltzmann identified what entropy actually is

7. Carnot Cycle – Most Efficiency Isothermal Expansion –Absorb heat from hot reservoir Adiabatic Expansion Isothermal Compression –Expel heat to cold reservoir Adiabatic Compression

8. Carnot Cycle

9. The Carnot Cycle maximizes the work by maximizing the temperature-entropy area.

10. Heat Engine QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine 1 2 3 4

11. Heat Engine QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine 1 2 3 4

12. Heat Engine QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine 1 2 3 4

13. Carnot Cycle – The Ocean Engine The oceanic temperature differences between surface and bottom have been used to create heat engines. At best, the surface is 300 K, and the bottom is 275 K. What is the maximum efficiency?

14. Carnot Cycle – The Ocean Engine In reality the heat bath and cold bath change temperature to average between the extremes and the midpoint temperatures. How much water must be cycled each second to run like the 1999-built U.S. ocean heat engine at 250 kW?

15. Carnot Cycle – The Ocean Engine

16. Refrigerators QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine

17. Refrigerators QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine Run a Carnot cycle in reverse for maximum COP. Example: House A/C assuming it’s Carnot (LOL!).

18. Refrigerators QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine COP, EER (Energy Efficiency Rating), SEER (Seasonal Energy Efficiency Rating)

19. Refrigerators QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine COP, EER (Energy Efficiency Ratio), SEER (Seasonal Energy Efficiency Ratio)

20. Air Conditioner QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine Compressor Condenser Throttle Evaporator (gas)(liquid)

21. Air Conditioner QhQh QcQc W Hot Reservoir, T h Cold Reservoir, T c Engine Compressor Condenser Throttle Evaporator (gas)(liquid)

22. Internal Combustion Engine 4-stroke Intake Combustible mixtures are emplaced in the combustion chamber Compression The mixtures are placed under pressure Power The mixture is burnt, almost invariably a deflagration, although a few systems involve detonation. The hot mixture is expanded, pressing on and moving parts of the engine and performing useful work. deflagration detonation Exhaust The cooled combustion products are exhausted into the atmosphere

23. Internal Combustion Engine 4-stroke Otto Cycle Power Stroke (adiabatic) Ignition Compression (adiabatic) Exhaust

24. Internal Combustion Engine 2-stroke

25. Internal Combustion Engine The Otto Cycle Nikolaus August Otto 1832-1891

26. Internal Combustion Engine The Otto Cycle

28. What is the highest efficiency achievable if the compression ratio is 10 (high by most car standards)?

29. Internal Combustion Engine The Otto Cycle How can we relate this back to temperature?

30. Diesel Engine Rudolph Diesel 1858-1913

31. Diesel Engine

36. Throttling Process – Joule Thomson

37. Hampson-Linde Cycle Hampson-Linde Siemens

38. Dilution Refrigerator

39. Laser Cooling http://www.colorado.edu/physics/2000/bec/lascool4.html

40. Laser Cooling v v