technology readiness of 5th and 6th generation compliant-v002

Technology Readiness of 5th and 6thGeneration Compliant Foil Bearing for

10 MWE S‐CO2 Turbomachinery SystemsH. Heshmat, J. F. Walton‡ and J. L. Cordova

The 6th International Supercritical CO2 Power Cycles SymposiumMarch 27 ‐ 29, 2018, Pittsburgh, Pennsylvania

Copyright © 2011‐2018 MiTi® 1

‡ Presenting Author

Overview• Objectives • Background• Technology• Summary and Conclusions


MITI Oil‐Free Turbomachinery ‐ Compressors

3

Hydrogen Pipeline Compressor

200 kW

Hydrogen Blower

1 kW

Fuel Cell Compressor

12 kW

Air Cycle Machine

30 kW

120,000 rpm360,000 rpm 60,000 rpm120,000 rpm

MITI Oil‐Free Turbomachinery ‐ Energy

4

60 kWe

Flywheel Electromechanical Battery

8 kWe

180,000 rpm

Gas Turbine Generator ORC Turbogenerator

65 kWe

30,000 rpm60,000 rpm

Objectives

• Identify Turbomachinery Concepts Capable Of Operating Efficiently With s‐CO2

• Identify Key Enabling Bearing Technology• Oil‐Free Compliant Foil Bearings• Use s‐CO2 Process Fluid for Hydrodynamics and Thermal Management• Scalable For Multi‐Megawatt Turbomachinery Applications from kW to 100s of MW


Preliminary Cycle Analysis for Net 10 MW System

6Copyright © 2011‐2018 MiTi®

Sink Source

Low T Recuperator

High T Recuperator

7.9 MPa

18.4 MPa

18.1 MPa750°C128 kg/s

60 krpmP = 11 MWe

8.0 MPa

Re‐CompressorMain Compressor

18.3 MPa

Preliminary 1st Order Aero Analysis


Turbine Rotor Concept


53.3 cm (21 inch)

35.6 cm (14 inch)

5 MW Turbo‐Compressor (2x)

Compressor Inlet

Compressor Discharge

Turbine Inlet

Turbine Discharge

Journal Bearings

Thrust Bearings


50‐80 krpm

General Bearing Characteristics

0 Speed or Reynolds No.0

20

40

60

80

100

RigidIncompressible

Fluid FilmBearing

Compressible FluidFilm Bearing

IncompressibleFluid

CompressibleFluid/Gas

Rolling ElementBearing

Speed

815

175150

Fluid Film

Rolling Element

Compliant Foil

Active Magnetic


Foil Bearing Fundamental Mechanisms


KHydro

KStruct

BHydro

BStruct

Coating

MiTi Korolon Coated Foil Bearings Demonstrated with Different Process Fluids


Air, H2, He(H2+H2O)

R134a, 245fa,R1233zd & R1234yf,

s-CO2

2-Phase Flow

Complexities of Mechanisms


Extent of Bearing pad surface compliancy10° (leading edge) 350° (trailing end)

0.0 0.2 0.4 0.6 0.8 1.0

Normalized Foil Compliancy Matrix


..

.

.

Foil Bearing Film Pressure and Height


Comparison of Rigid vs Compliant Bearingsat 60,000 rpm

0

250

500

750

1,000

1,250

1,500

1,750

2,000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Maxim

um Loa

d (lbs)

Eccentricity Ratio

Foil Bearing Compressible

Rigid BearingCompressilbe


s‐CO2 Foil Bearing Characteristics

‐6.00E+06

‐4.00E+06

‐2.00E+06

0.00E+00

2.00E+06

4.00E+06

6.00E+06

8.00E+06

1.00E+07

1.20E+07

0.0

0.5

1.0

1.5

2.0

2.5

0.00 0.20 0.40 0.60 0.80 1.00

Stiffne

ss (lb/in)

Min Film

(mils) &

Pow

er (H

P)

Eccentricity Ratio

2.5 Inch Diameter Foil Bearing Performance vs Eccentricity ratio at 60 krpm

HN (mils) P (HP) KXX KXY KYX KYY

Power Loss

Stiffness

Min. Film Height

Film Pressure, Load and Stiffness With

Turbulence


Load PerformanceDynamic Characteristics

Foil Bearing for 100 MW Scale

‐5.00E+06

0.00E+00

5.00E+06

1.00E+07

1.50E+07

0 2,000 4,000 6,000 8,000 10,000

Stiffne

ss (lb/in)

Speed (rpm)

3150 lb Turbine Speed Dependent SCO2 Foil Bearing Stiffness

KXX KXY KYX KYY


Scalability of Foil Bearings from 1 to 100s MWe


20

KorolonTM 1350A coated foil after 50 thermal cycles and bend testing

YSZ coated foil fractured after thermal cycling and bend testing

Representative sets of thermal cycles for thin foils

Bend Testing After 815°CThermal Cycling

815°C

95°C

Korolon

YSZ

Copyright © 2011‐2018 MiTi®

MiTi Bomb Setup to Expose Korolon Coated Foils to SCO2 at >675oC and >80 Bar


Korolon Coated Bearing Foil Before & After Exposure to SCO2

Pretest Bend Posttest Bend


Post Exposure Tribological Test


MiTi Korolon™ Coated Foil Sample After Exposure to 650°C SCO2 and 500 Start/Stop Cycles


Measured High Temperature Foil Bearing Performance


Thermal Performance of Foil Bearing Gen IV


Bearing Len x Diam = 100 x 75 mm2

26

5+ Hour Elevated Temperature Test

Time (Minutes)0 50 100 150 200 250 300 350

Tem

pera

ture

(C)

0

200

400

600

800

1000

Spee

d (k

rpm

)

0

5

10

15

20

25

30

35

Bearing Chamber

Bearing Inboard

Speed

Bearing Free End

20269‐T16R3ABCD


High Temperature Foil Bearing


870°C

815°C

Bearing Housing and Foil Temperatures

Bearing Shell Temperatures Bearing Foil Temperatures


Foil Bearing Generations/Classes


Summary & Conclusions• s‐CO2 Turbomachinery is Compact and Operates at High‐Speed • High Temperature s‐CO2 Environment Restricts Use of Conventional Bearing Technologies and Lubricant Systems

• Compliant Foil Gas Bearings Are an Enabling Technology • Preliminary Testing Shows Korolon Coated 6th Generation Foil Bearings Have Capabilities to Meet Needs for s‐CO2 Systems From kW to 300 MW

• High Temperature Testing to 870°C• High Load Capacity• High Speed with Low Power Loss

• Further Verification and Demonstration of Korolon Coated Foil Bearing Performance and Durability in High Temperature s‐CO2 is Underway


Acknowledgements

• U. S. Department of Energy under Award No. DE‐SC0015811. • The authors particularly acknowledge the support of Mr. Brian K. Robinson at DOE.


Thank you!

Backup


Compressibility of s‐CO2

0.001

0.01

0.1

1

10

10 100 1000 10000 100000

Bearing Num

ber/Co

mpressibility

Ambient Pressure (psia)

Compressibility of Gas

Air_72F CO2_90F CO2_800F CO2_1200F

Threshold P Threshold‐L 7.9 MPa

~15 MPa

Incompressible

Compressible

Supercritical CO2

7.9 MPa


Λ 6 ⁄ ⁄

Bearing Requirements/Environment ‐ Scaling

Power Pressure Temperature Weight Speed(MW) (MPa) (°C) (kg) (rpm)1 7.8 ‐ 30 650 ‐ 750 1‐2 120,00010 7.8 ‐ 30 650 ‐ 750 100 50,000100 7.8 ‐ 30 650 ‐ 750 1500 10,000300 7.8 ‐ 30 650 ‐ 750 >5,000 5,400


MITI Oil‐Free Bearings and Seals


Thrust Foil Bearing

15‐250 mm

80 psi / 650°C

Foil Face Seal

25‐1300 mm

>80 psid / 650°C

Foil RadialSeal

20‐250 mm

>100 psid / 870°C

6‐150 mm

100 psi / 870°C

Journal FoilBearing

Startup/Shutdown Cycles0 50000 100000 150000 200000

Coe

ffici

ent o

f Fric

tion

0.0

0.1

0.2

0.3

0.4

0.5

Run

ning

Coe

ffici

ent o

f Fric

tion

0.000

0.005

0.010

0.015

0.020

0.025

Korolon Coated Foil Bearing Life Test

38

Friction During Shutdown


Friction During Operation

technology readiness of 5th and 6th generation compliant-v002

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