Selection of Rankine Cycles for Various Resources

Match the Cycle and Resource …

P M V Subbarao

Professor

Mechanical Engineering Department

Pressurised Water Reactor (PWR)

– Over 60% of all installed commercial reactors are pressurised water reactors and like 85% of all reactors they use enriched Uranium as the fuel.

– The use of enriched fuel means that a higher power density is achievable in the core and thus better efficiency.

– PWR reactors use a two stage heat transfer system with ordinary (light) water acting as both a moderator and the coolant in the primary circuit.

– The water in the primary circuit reaches a temperature of about 325°C and must be at very high pressures, so that it can not boil.

– It gives up its heat in a second heat exchanger which produces the steam in the turbine circuit based on the Rankine cycle.

– Typical output power is 1000MW with a system efficiency of 33%.

Progress in 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 15.9 24.1

Th oC 260 316 454 482 538 566 566 565 538

Tr oC -- -- -- -- 538 538 566 565 538

FHW -- 2 3 4 6 6 7 8 8

Pc,kPa 13.5 5.1 4.5 3.4 3.7 3.7 4.4 5.4 5.1

,% -- ~17 27.6 30.5 35.6 37.5 39.8 39.5 40

Optimal Design of Vapour Power Plant

satcond pp

ambinCW TT ,

outCWT ,

?TTD

inssteam Tm , &

exitcsteam Tm , &

incwcw Tm , & exitcwcw Tm , &

Thermal Model of A Steam Condenser

Hot Well

Energy Balance of A Condenser

• Energy balance:

• The temperature rise of cooling water:

• 6 to 7 degree C for single pass.

• 7 to 9 degree C for double pass.

• 10 to 12 degree C for four pass.

LMWiWeWCWexitcincc TUATTCmhhm

,,

Condenser Temperature Vs Efficiency

0.30.320.340.360.380.4

0.420.440.46

0 20 40 60 80 100 120

Tc

Eff

Condenser Temperature Vs Quality

0.68

0.7

0.72

0.740.76

0.78

0.8

0.82

0 20 40 60 80 100 120

Tc

x4

0.265

0.270

0.275

0.280

0.2850.290

0.295

0.300

0.305

0.310

0 20 40 60 80 100 120

Tc

X4.E

ff

0

500

1000

1500

2000

2500

3000

3500

0 20 40 60 80 100 120

Qin

Wnet

c

Mean Effective Pressure

0100200300400500600700800

0 20 40 60 80 100 120

Tc

p, k

Pa

34

36

38

40

42

44

46

0 20 40 60 80 100 120 140

Pressure,bar

Eff

icie

ncy,%

tc=20 c ( 18 mm Hg)

tc=27 C (50 mm Hg)

tc=36 C (75 mm Hg)

Effect of inlet steam pressure (P) and condenser pressure on Rankine efficiency with constant inlet steam temperature of 470o C

Power Loss Due to Excess Back Pressure

Further Developments in Carnotization of Rankine Model

BY

P M V SubbaraoProfessor

Mechanical Engineering DepartmentI I T Delhi

Suppression of Non-Isothermal Heat Addition Zones…..

C

C

C

Reassessment Thru Carnot Model