Solid Oxide Fuel Cell System Development and R&D Needs · Solid Oxide Fuel Cell System Development and R&D Needs Nguyen Minh SECA Core Technology Program Planning Workshop February

Solid Oxide Fuel Cell SystemDevelopment and R&D Needs

Nguyen Minh

SECA Core Technology Program Planning WorkshopFebruary 14-15, 2001

Atlanta, GA

0102 seca core.ppt- 2

Turbo-Compressor(E&S, Automotive Products)

SimplifiedSimplified SOFC System & ComponentsSOFC System & Components

High-T Heat Exchangers(E&S, TPS)

Valves(E&S, HBC)

Controllers(E&S, HBC)

Blowers(E&S)

Sensors(E&S, HBC)

Thermal Management

AirManagementAir

FuelProcessorFuel

ProcessExhaust

Solid OxideFuel Cell Stack

DC Power

AnodeExit

CathodeExit

CathodeInlet

AnodeInlet

SOFCStack (E&S, HTC)

SOFCFuel Cell (E&S, HTC)

CPOX Fuel Processor(HTC)

Gas TurbineP

ower

Turbine Inlet

Microturbine(TPS)


Solid Oxide Fuel Cell Battery ChargerSolid Oxide Fuel Cell Battery Charger

Anode Fin

AlloyInterconnect

Cathode Fin

Single Cell

Fuel Passage

OxidantPassage

FuelPassage


500500--W SOFC Battery Charger W SOFC Battery Charger -- CharacteristicsCharacteristics

• Targets– Weight = 7 kg– Voltage = 28 VDC– Operation on logistic fuels (JP and diesel)– Portable

• Key technologies– Reduced-temperature solid oxide fuel cell (SOFC) for power

generation– Catalytic partial oxidation (CPOX) for processing logistic fuels


System Design MethodologySystem Design Methodology

• Propose Conceptual Design• Assume Components• Model System

• Design Components• System Analysis• Trade Studies

• Compare to Requirements•Identify Gaps

Conceptual SystemDefinition

Technology Gaps

System Definition

TechnologyDevelopment

System Requirements Technology Base


Fuel Cell Assembly Weight OptimizationFuel Cell Assembly Weight Optimization

• 500 Watt; 28 Vdc Output• Hydrogen Utilization: 0.8• Inclusion of Manifolds• Inclusion of Insulation of Exposed Surface Areas (Tsurface

140°F)


363.2°F 1362°F

193.3°F 1382°F

1562 - 363.21562 - 193.3

= .875ε HOT=

AirAir--toto--Air Heat Exchanger RequirementsAir Heat Exchanger Requirements

• High Temperature Effectiveness Impose Counter Flow Design


Air to Air Heat Exchanger PerformanceAir to Air Heat Exchanger Performance

• Alloy Construction• Fin: 16R-.125-1/8 (0)-.004

Hot Air InCold Air

Out

Hot Air Out

Cold AirIn

3

2.5

2

1.5

1

0.5

00.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9

Cell Voltage, V

Asse

mbl

y W

eigh

t, KG


System Performance CharacteristicsSystem Performance Characteristics

• Hydrogen Utilization: 0.8


Fuel Cell Performance CharacteristicsFuel Cell Performance Characteristics

• Cell Voltage

• Hydrogen Utilization

• Fuel Flow, lb/hr

• Air Flow, lb/hr

• Gross Power, W

• System Efficiency, %

Cross Flow

0.65

0.84

0.361

40.7

584.9

25.07

Radial Flow

0.65

0.84

0.361

43.3

587.3

24.91


CPOX Performance MetricsCPOX Performance Metrics

• Duration: 700 hours to date

• Thermal Cycles: 10

• Sulfur Tolerance: 1000 ppmdibenzothiophene in JP-8

• Yield: 70-80% of LHV in JP-8

• Duration: 700 hours to date

• Thermal Cycles: 10

• Sulfur Tolerance: 1000 ppmdibenzothiophene in JP-8

• Yield: 70-80% of LHV in JP-8

0%

20%

40%

60%

80%

100%

0 40 80 120 160 200 240 280 320

Perc

ent Y

ield

%

Time (Hours)

H2

COThermal Cycle


SOFC Stack MetricsSOFC Stack Metrics

• 10 cm x 10 cm footprint• 800°C operation in hydrogen and air at ambient pressure• Power:

– 1.1 kW at 0.7 V / cell– 1.4 kW at peak power

• Power density: – 0.42 W/cm2 at 0.7 V/cell– 0.6 W / cm² at peak power– 0.7 kW / kg, 0.7 kW / L at peak power– 0.53 kW / kg, 0.53 kW / L at 0.7 V/cell

• 10 cm x 10 cm footprint• 800°C operation in hydrogen and air at ambient pressure• Power:

– 1.1 kW at 0.7 V / cell– 1.4 kW at peak power

• Power density: – 0.42 W/cm2 at 0.7 V/cell– 0.6 W / cm² at peak power– 0.7 kW / kg, 0.7 kW / L at peak power– 0.53 kW / kg, 0.53 kW / L at 0.7 V/cell

30 Ce ll Sta ck , 4"x4" Footprint 800°C

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

0 .000 0.100 0.200 0.300 0.400 0.500 0.600 0.700Curr ent Density (A/cm ²)

Volta

ge (V

)

0

200

400

600

800

1000

1200

Pow

er (W

)

Stack V oltagePow er


Thermal Cycling Thermal Cycling

• Multiple thermal cycles without significant performance degradation

• Minimal change in open circuit voltage and voltage under load between cycles

• Multiple thermal cycles without significant performance degradation

• Minimal change in open circuit voltage and voltage under load between cycles

SOFC stacks are being engineered for thermal cycling capabilitySOFC stacks are being engineered for thermal cycling capability

Stack 28 Performance at 800oC in H2

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 100 200 300 400 500 600 700 800

Time-on-Stream (h)

Volta

ge (V

)

Cell 1 VCell 2 V

529 mA/cm21 slpm H237.5% FU

Performance at 800°C in H2


CPOX/SOFC Integration CPOX/SOFC Integration -- Key Parameters Key Parameters

• Start-up and shut-down procedures• Range of operating parameters• Pressure drop• Thermal management• Transient characteristics


Integrated CPOXIntegrated CPOX--SOFC OperationSOFC Operation

Air

FuelCPOX Reformate SOFC

CPOXOutput

17.3% H221.0% CO0.7% CO211.0% H2O50.0% N2

InputJP-8Air

Demonstration of multicell SOFC operation on JP-8 syngasDemonstration of multicell SOFC operation on JP-8 syngas

Module Operating on CPOX Productat 800°C

00.20.40.60.8

1

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Current Density [A/cm²]

Volta

ge (V

)

0.000

0.050

0.100

0.150

0.200

Pow

er D

ensi

ty

[W/c

m²]

V PD


50 W Demonstration Unit50 W Demonstration Unit

• Demonstration of key component integration– Integration of system

components, especially CPOX fuel processor and SOFC stack

• Self contained operation– Startup– Thermal integration– Propane fuel

• Demonstration of key component integration– Integration of system

components, especially CPOX fuel processor and SOFC stack

• Self contained operation– Startup– Thermal integration– Propane fuel


Operational Mode Inputs

Com

man

d flo

w

System-level control

Subsystem

Subsystem

Subsystem

Control System Functions Control System Functions -- drives integrationdrives integration

• Coordinate subsystems for shared resources and efficient operation

• Regulate yet be responsive over a wide operating range– Flow / Composition – Temperature– Pressure– Power

• Provide safe system operation through built-in test

• Perform process and component health monitoring for improved life cycle

• Provides user interface and automated system operation– Startup/ Shutdown– Scheduled operation– Status indicators/alarms


Control Development ApproachControl Development Approach

• Develop dynamic system models and design control through simulation.

• Rapid prototyping capabilities allows quick evaluation of controls designed in simulation.

• Advanced control and sensing techniques can be investigated through simulation trade studies and prototyping. The most promising approaches implemented in product.

PlantSensors

Feedback

Feedforward

Estimation

Controls

Rapid Prototyping


SOFC System SOFC System -- R&D NeedsR&D Needs

• System Analysis and Modeling• System Thermal Management including

– Thermal cycling– Startup

• Fuels and Fuel Impurities• Controls/Sensors• Power Electronics


System Analysis and Modeling R&D NeedsSystem Analysis and Modeling R&D Needs

• System Steady-State Models– Component models– System performance

• Dynamic System Models– Component models– Transient performance

• SOFC Design and Performance Analysis– Thermal– Stress– Performance


Thermal Management R&D NeedsThermal Management R&D Needs

• Heat Exchanger and Insulation– Low-cost high-temperature alloys/composites– Oxidation resistant coating for low grade metals– Low-cost insulation materials/methods

• Thermal Cycling– Models to predict thermal cyclability of SOFC stacks– Modifications of material coefficient of thermal expansion

• Startup– Methods to minimize startup times– Thermal shock resistant materials/components


Fuels and Fuel Impurities R&D NeedsFuels and Fuel Impurities R&D Needs

• Influence of Fuels on SOFC and Fuel Processor Operation– Performance– Fuel flexibility

• Impurity Effects– Performance degradation– Tolerance level– Life

• Methods to Remove Sulfur from Hot Gases


Advanced Sensing Advanced Sensing and and

Control SolutionsControl Solutions

Systems Technologies Systems Technologies for Improved for Improved

Performance & CostPerformance & Cost

Control & Sensing R&D NeedsControl & Sensing R&D Needs

• Advanced sensing and control technology -improved performance/cost– Advanced control and optimization technologies– Integrated embedded system implementations – Fuel composition and carbon monoxide (CO) sensors

• Advanced modeling for control development and information processing - address critical control challenges at component and system levels– System-subsystem-component dynamic modeling for

control development– Bridging sensing and control: information-from-data

technologies for control, safety, & system health

• Advance sensor development - address critical sensing challenges– Advanced sensing technologies for high temperature,

flow and composition sensing


Power Electronics R&D NeedsPower Electronics R&D Needs

• Fuel Cell/Power Inverter Interface– Interface impedance calculation method for maximizing

efficiency of fuel cell systems

• Power Conversion Architecture– Modeling and analysis of various architectures of power

conversion systems (PCS)

– Optimization of PCS architectures for various applications

Documents

Solid Oxide Fuel Cell System Development and R&D Needs · Solid Oxide Fuel Cell System Development and R&D Needs Nguyen Minh SECA Core Technology Program Planning Workshop February