1. Carnotization of Rankine Cycle
P M V Subbarao
Professor
Mechanical Engineering Department
Enhance Mean Temperature of Heat Additions thru Additional Process …..

2. Structure of Healthy Rankine Cycle
3sup
4sup
3sub
4sub T 2 1 s

3. Historical Progress in Rankine Cycle

4. Ill Effects of High Pressure Cycles
Why so?
Why should an isentropic expansion lead to condensation??? x
Pressure, MPa

5. Few Low Temperature Resources and Their Capacities

6. Characterization of Working Fluids for Rankine Cycle

8. Working Fluids for Low Temperature Resources
Organic Substances must be selected
in accordance to the heat source
temperature level (Tcr < Tin source)

9. Family of Rankine Cycles

10. World Installed Capacity of ORC Plants
Total installed capacity : MWel, in 563 power plants
New capacity planned : MWel in 75 plants

11. Law of Recognition of New Concepts

12. Progress in Steam Rankine Cycle
Year
1907
1919
1938
1950
1958
1959
1966
1973
1975 MW 5 20 30 60
120
200
500
660
1300
p,MPa
1.3
1.4
4.1
6.2
10.3
16.2
15.9
24.1
Th oC
260
316
454
482
538
566
565
Tr oC --
FHW 2 3 4 6 7 8
Pc,kPa
13.5
5.1
4.5
3.4
3.7
4.4
5.4
h,%
~17
27.6
30.5
35.6
37.5
39.8
39.5 40

13. Reheating of Steam to Enhance Quality at the Turbine Exit
Single Turbine drum

14. Analysis of Reheat Cycle
Consider reheat cycle as a combination of Rankine cycle and horn cycle.
Cycle = Cycle ’-1 + Cycle 4’ ’.
Therefore, 4’ 6

15. Analysis of the Horn Cycle
4’ – 4 Isentropic Compression.
4 – 5 Isobaric Heat Addition.
5 – 6 Isentropic Expansion
6 – 4’ Isobaric(thermal) cooling.
4’ 6

16. Clues to Achieve Double Benefit
Select appropriate reheat pressure, pRH, such that above function is maximum with better value of x.

17. Procedure to Determine Optimum Reheat Pressure
Calculate the efficiency of Rankine cycle, hRankine.
Calculate mean effective temperature of heat addition, Tm,in using s
Find out pressure corresponding to Tm,in and entropy at HP turbine exit.
Add reheating at this pressure and calculate efficiency of the Reheat Cycle.

18. pmax= 15 MPa
Tmax= 550 0C
Tsat= C

19. Effect of Reheat Pressure
Dh,%
1.0
0.2
0.4
0.6
0.8
~0.3
prh/pmax

20. Reheating : A Means to implement High Live Steam Pressure
Supercritical
593/6210C
593/5930C
565/5930C
565/5650C
538/5650C
Improvement in Efficiency, %
538/5380C

21. Super Critical Cycle ~ 1990

22. Ultra Supercritical Installations of The World

23. Single-Reheat Ultrasupercritical Product Line GE Power

24. Double Reheat Ultra Super Critical Cycle8

25. Reheater Pressure Optimization for Double Reheat Units
97bar
110bar
69bar

26. 21st century Rankine Cycles
Improvement in Efficiency, %

27. Super Critical Cycle of Year 2005

28. Double Reheat Super Critical Plants
Net efficiency on natural gas is expected to reach 49%.
Net efficiency on coal is expected to reach 47%.

29. Double-Reheat Ultrasupercritical Product Line GE Power

30. Advanced 700 8C Pulverised Coal-fired Power Plant Project

31. FUTURE ULTRA SUPERCRITICAL PLANT – UNDER DEVELOPMENT
EFFICIENCY 55 %