inlet temperature sensitivity presentation · presentation summary ... turbo-generator...

Supercritical CO2 Power Cycles Symposium March 29-31, 2016

Sensitivity of an Operating

Supercritical Carbon Dioxide Brayton Cycle

to Compressor and Turbine Inlet Temperature

Eric Clementoni

Bechtel Marine Propulsion CorporationBettis Atomic Power LaboratoryWest Mifflin, PA


Presentation Summary

• sCO2 Brayton Cycle Integrated Systems Test

(IST) Overview

• Compressor Inlet Temperature Sensitivity

– System Control

– Test Results

• Turbine Inlet Temperature Sensitivity

– System Control

– Test Results


• 100 kWe IST has been main sCO2 development

focus of BMPC

• Simple Brayton cycle

– Single variable speed turbine-compressor

– Single constant speed turbine-generator

– Single recuperator

• Focus on system control

– Rapid startup

– Power changes

– Shutdown

IST Overview

CompressorTurbine

Heat

Source

Generator Turbine

Recuperator

Precooler

Sea WaterCooling

Water


IST Physical Layout

Hot Oil System

Turbo-Generator

Turbo-Compressor

Recuperator

Precooler

Turbine Throttle Valves

Compressor Recirculation Valve

Leakage Collection Compressors


IST Physical Layout

Turbo-Generator

Recuperator

Precooler

Turbo-Compressor (not

visible)


IST Turbomachinery

Turbo-Generator

Turbo-Compressor

Compressor/Diffuser Turbine

Thrust Bearing


Normal Thermal-Hydraulic Control

IHX

GenMot/

Gen

Pre

coo

ler

Recuperator

Load regulated to

maintain 60,000 rpm

shaft speed

No load

PI control

regulates

TC shaft

speed

TC speed

setpoint

function of

TG load

setpoint

T T C


IST Efficiency vs. Power

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

0 5 10 15 20 25 30 35 40 45

Cy

cle

Eff

icie

ncy

Output Power (kW)


Compressor Inlet Temperature

Sensitivity Overview

IHX

GenMot/

Gen

Pre

coo

ler

Recuperator

Load regulated to

maintain 60,000 rpm

shaft speed

No load

PI control

maintains

TC shaft

speed at

setpoint

TC speed

setpoint

fixed at

48,670 rpm

T T CHeater power

automatically controlled

to maintain CO2 outlet

temperature of 440°F

System mass held constant,

compressor inlet pressure varies

based on system conditions

Chilled water flow


to obtain desired

compressor inlet

temperature

Range: 90-102°F


39.5

40

40.5

41

41.5

42

42.5

43

43.5

44

44.5

0

200

400

600

800

1000

1200

1400

1600

1800

2000

90 92 94 96 98 100 102 104

Pre

ssu

re (

psi

a)

Compressor Inlet Temperature (F)

Compressor Inlet Pressure

Compressor Outlet Pressure

Compressor Inlet Density

De

nsi

ty (

lbm

/ft3

)

Compressor Inlet Conditions

Normal IST operating

conditions


Compressor Flow & Brayton Power

0

5

10

15

20

25

30

90 92 94 96 98 100 102 104

Co

mp

ress

or

Flo

w (

lbm

/s)

or

Bra

yto

n O

utp

ut

Po

we

r (k

W)


Brayton Output Power

Compressor Flow


Cycle Efficiency

5.0%

5.1%

5.2%

5.3%

5.4%

5.5%

5.6%

90 92 94 96 98 100 102 104

Bra

yto

n C

ycl

e E

ffic

ien

cy



Cycle Efficiency

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

0 5 10 15 20 25 30 35 40 45

Cy

cle

Eff

icie

ncy

Output Power (kW)


Cycle Efficiency

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

0 5 10 15 20 25 30 35 40 45

Cy

cle

Eff

icie

ncy

Output Power (kW)

91°F103°F


Turbine Inlet Temperature

Sensitivity Overview

IHX

GenMot/

Gen

Pre

coo

ler

Recuperator

Load regulated to

maintain 60,000 rpm

shaft speed

No load

Valve

position

fixed at

36% open

TC speed

varies with

turbine inlet

temperature

T T CHeater power


to maintain CO2 outlet

temperature

Range: 390-440°F

System mass held constant,

compressor inlet pressure varies

based on system conditions

Chilled water flow


to obtain desired

compressor inlet

temperature of 96°F


Power and Compressor Speed

40000

42000

44000

46000

48000

50000

52000

0

5

10

15

20

25

30

380 390 400 410 420 430 440 450

Bra

yto

n O

utp

ut

Po

we

r (k

W)

Turbine Inlet Temperature (F)

Brayton Output Power

Compressor Speed

Co

mp

ress

or

Sp

ee

d (

rpm

)


Cycle Efficiency

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

380 390 400 410 420 430 440 450

Bra

yto

n C

ycl

e E

ffic

ien

cy

Turbine Inlet Temperature (F)


Cycle Efficiency

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

0 5 10 15 20 25 30 35 40 45

Cy

cle

Eff

icie

ncy

Output Power (kW)

440°F

390°F


Summary

• IST response to varying compressor and

turbine inlet temperatures consistent with

most expectations

– Cycle efficiency benefit from reducing compressor

inlet temperature diminished in a fixed mass

system

– Cycle efficiency vs. output power appears to not

be strongly influenced by turbine inlet

temperature


Acknowledgements

• This presentation summarizes work that has

been performed a number of devoted

engineers, scientists, technicians, and support

personnel at the Bechtel Marine Propulsion

Corporation and our subcontractors. This

paper would not be possible without the

efforts of this team.

inlet temperature sensitivity presentation · presentation summary ... turbo-generator...

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