1. Diesel Cycle and the Brayton Cycle Chapter 9b

2. Rudolph Diesel  German inventor who is famous for the development of the diesel engine  The diesel engine is based on a compression ignition system http://www.autonews.com /files/euroauto/inductees/d iesel.htm

3. Diesel Engines  No spark plug  Fuel is sprayed into hot compressed air

4. State Diagrams for the Diesel Cycle

5. Diesel CycleOtto Cycle The only difference is in process 2-3

6. Consider Process 2-3  This is the step where heat is transferred into the system  We model it as constant pressure instead of constant volume

7. Consider Process 4-1  This is where heat is rejected  We model this as a constant v process That means there is no boundary work

8. As for any heat engine… substitute

9. Rearrange r c is called the cutoff ratio – it’s the ratio of the cylinder volume before and after the combustion process

10. rcrc This doesn’t do us much good

11. rcrc Since Process 1-2 and Process 3-4 are both isentropic 11

12. Finally, Since process 1-2 is isentropic The volume ratio from 1 to 2 is the compression ratio, r

13. Which finally gives…

14. k=1.4

15. The efficiency of the Otto cycle is always higher than the Diesel cycle  Why use the Diesel cycle?  Because you can use higher compression ratios

16. Typical range for gasoline engines

17. P-v Diagram for an ideal dual cycle

18. Brayton Cycle  Ideal Cycle for Gas Turbine Engines Usually operate on an open cycle

19. Closed cycle model for a gas turbine engine 1-2 Isentropic Compression 2-3 Constant Pressure heat addition 3-4 Isentropic Expansion 4-1 Constant Pressure heat rejection

20. Closed cycle model for a gas turbine engine 1-2 Isentropic Compression 2-3 Constant Pressure heat addition 3-4 Isentropic Expansion 4-1 Constant Pressure heat rejection

22. Remainder of the Chapter  I’m not skipping the other sections in this chapter because they are unimportant, or uninteresting  We just don’t have time!!