An Introduction to Solid Oxide Fuel Cell Research at CUED

1
An Introduction to Solid Oxide Fuel CellResearch
at CUED
By Ben Haberman
2
Introduction

• The fuel cell
• The Rolls-Royce design
• Results
• Conclusions
• Any Questions?

3
The Fuel Cell
Air flow
Fuel flow
Porous Anode
Electr- olyte
Porous Cathode
H2O
O2-
O2-
H2
O
O2
2H
2e-
2e-
Load
4
Reversible Operation
In open circuit conditions
5
Realistic Operation
6
The Rolls Royce Design
Fuel cells
60 mm
Air flow
Ceramic module
150 mm
Fuel flow
7
The Fuel Cell Components
100 H2O
5 Fuel cell bundles
Air flow
810C 700 Nl/min
950C
Fuel flow 865C
7Nl/min of 100 H2
8
A Hybrid System Replacing Combustion Chamber
Load
Combustor
Fuel cells
Fuel inlet
Remaining fuel and air
Pressure vessel
Exhaust
Air inlet
Turbine
Generator
Compressor
9
What Do We Want to Know?

• Electrical power and heat generation
• Gas conditions at surfaces of electrolyte
• Fuel utilisation

10
Code Development

• Original code
• 3D Compressible flow solver by Prof. Denton
• Explicit time-marching method for Transonic flows
• New gas channel code
• Include all relevant physical phenomena
• Very stiff equations - simplified preconditioning
  method
• Porous code
• Time marching as before
• New model Cylindrical Pore Interpolation Model
  (CPIM)

11
Results Model Description

• Cannot model complete bundle
• Can look at infinite array
• Only need 2 modules
• Appropriate periodic bcs

12
Boundary Conditions

• Air Inlet
• Temperature 865C
• Pressure 7 bar
• Composition 21O2, 79N2
• Flow rate 70 Nl/min per air channel
• Fuel Inlet
• Variable Temperature 865-900C
• Composition 45H2, 21H2O, 10CO2, 24CO
• Flow rate 1 Nl/min per fuel channel
• Fuel cells
• Fixed current density 3000Am-2

13
Model Control Volume
Fuel cells
Fuel outlet
Fuel inlet
Surrounding repeating unit

• Over 3 million grid cells
• Simulation required 3 months computer time

14
Hydrogen
XH2
z / mm
20
Fuel outlet
16
12
Fuel cells
8
4
0
Fuel inlet
x / mm
0
20
40
60
80
100
120
140
15
Carbon Monoxide
XCO
z / mm
20
16
12
8
4
0
x / mm
0
20
40
60
80
100
120
140
16
Temperature
z / mm
Temperature (C)
893 891 889 887 885 883 881 879 877 875
20
16
12
8
4
0
x / mm
0
20
40
60
80
100
120
140
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Summary of Results

• Fuel consumption
• 12 of H2 and 7 of CO used
• Without shift reaction 14.5 of H2 used
• Shift reaction produces
• 12 of H2 near fuel inlet
• 20 of H2 near fuel outlet
• Net temperature rise
• 40C along air channels
• 0C along fuel channels

18
Operating Voltage
y / mm
Voltage (V)
6
4
2
0
x / mm
0
30
60
90
120
150
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Conclusions

• Each module produces 12.5 W of power
• Component efficiency 59
• Rolls-Royce design is very good
• High gas flow rates
• Bundle geometry
• Further simulations required
• Whole bundle
• Experimental validation

20
Thank You for Listening

• Any Questions ?