Cabrera Cano, Enrique May 2014 Assignment Project M.Sc. Energy Systems, FH Aachen
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Introduction
Objectives
Theoretical Background
Experimental Settings ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Results ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Conclusions
Appendix
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Membrane electrode assembly (MEA)
Gaskets and End plates
Bipolar Plates
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1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jülich GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
Distribution of gases,
Prevention of gas leakage,
Separation of the fuel and oxygen/air,
Collection of electrical current produced
Chemical, mechanical and thermal stability
4 6/11/2014 7:27 PM
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jülich GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
5
Nr. Requirement Target Unit
1 Electrical resistivity ˂ 0.01 Ω cm
2 Corrosion resistance ˂ 16 µA/cm²
3 Thermal conductivity ˃ 10 W/mK
4 Compression strength 42 bar
5 Density (Weight/Volume) ˂ 5 g/cm3
6 Costs ˂ 0.0045 US$/cm²
6/11/2014 7:27 PM
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jülich GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
2. Methta, Vial; Smith, Joyce: Review and analysis of PEM fuel cell design and manufacturing; Journal of Power Sources 114 (2003) 32-53
Introduction
Objectives
Theoretical Background
Experimental Settings ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Results ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Conclusions
Appendix
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1. Analysis of Electrical properties of three different Bipolar plate materials
◦ 70%, 75%, 80% weight percentage of graphite, rest of polypropylene
2. Influence of the manufacturing process on the measured material
3. Influence of applied pressure on the total resistance
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Introduction
Objectives
Theoretical Background
Experimental Settings ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Results ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Conclusions
Appendix
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Resistance depends on:
I. The type of material
II. The length
III. The thickness
IV. The temperature
For a given material at constant temperature
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3. Mc Tavish, J.P.: Foundation Electrical Engineering; Prentice Hall International (UK) Ltd. (1996); ISBN: 0-13-309931-8
𝑹 ∼𝒍
𝑨
Constant of resistivity (ρ) takes into account the type of material:
𝑹 = 𝝆𝒍
𝑨
Conductivity (σ ) reciprocal of resistivity
𝑮 =𝟏
𝑹[𝜴]= 𝑺 𝑮 = 𝝈
𝑨
𝒍
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3. Mc Tavish, J.P.: Foundation Electrical Engineering; Prentice Hall International (UK) Ltd. (1996); ISBN: 0-13-309931-8 4. Maxfield, Clive: Electrical Engineering, Elsevier Inc.,United States of America (2008); ISBN: 978-1-85617-528-9
Pure Graphite 6 ◦ Electrical conductivity
◦ Thermal conductivity
◦ sophisticated & costly processing
◦ unsuitable for reasons of stability
1. Electro graphite 2. Carbon – carbon composite 3. Sheet Metal 4. Flexible graphite foil 5. Graphite polymer composite 6
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Proportion between graphite and polymer 1: ◦ 75% - 80% of graphite
◦ Balance: electrical conductivity and mechanical stability
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jülich GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
6. Middelman, E.;Kout, W.; Vogelaar, B.;Lenssen, J.; de Waal, E.: Bipolar plates for PEM fuel cells; Journal of Power Sources 118 (2003) 44 – 46
Compression molding
Injection molding
Two-component injection molding
Preform molding
Advantages ◦ Automated production,
◦ Short cycle time and
◦ Accurate size
Disadvantages
◦ Excessive mold wear
◦ Limited size of thickness ratio and
◦ Could affect conductivity
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6. Middelman, E.;Kout, W.; Vogelaar, B.;Lenssen, J.; de Waal, E.: Bipolar plates for PEM fuel cells; Journal of Power Sources 118 (2003) 44 – 46
Bulk resistance ◦ Ohmic resistance of the
component or material
Contact resistance ◦ Resistance at the interface of
two different surfaces in contact with each other
Total resistance: ◦ Contact resistance + bulk
resistance of the individual components
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5. Prakash, C. Ghosh; Dey Tapobrata; Singdeo, Debanand: Contact resistance between bipolar plate and gas diffusion layer in high temperature polymer electrolyte fuel cells; International Journal of Hydrogen Energy 39 (2014) 987-995
𝑹𝐓𝐎𝐓 = 𝑹𝟏/𝟐 + 𝑹𝟐/𝟑 + 𝑹𝟑 + 𝑹𝟐 + 𝑹𝟏
Introduction
Objectives
Theoretical Background
Experimental Settings ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Results ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Conclusions
Appendix
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25mm
38mm
2.1mm
Thirty samples made from three different materials each in equal number
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Two different configurations were designed: • in-plane and
• through-plane
Two different orientations: 1. in the injection direction
2. perpendicular to the injection direction
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Parameter Value Unit
Current flow area of
injection direction
orientation
0.525
𝑐𝑚2
Current flow area of
perpendicular to injection
direction orientation
0.798
𝑐𝑚2
Electrical Current 0.85 A
Sample
Multimiter
Multimiter
Power supply
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V R
I
ΔX=2cm
I
a
b
c
I
1 2 3
a = 6.25 mm
b= 12.5 mm
c= 18.75 mm
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ΔX=2cm
I
a
b
c
I
4 5 6
a = 9.50 mm
b= 19.00 mm
c= 28.50 mm
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Voltage measurement
Current measurement
Beam
Weight
Power supply
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Pressure distribution analysis
Parameters
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Parameter Value Unit
Reference measurement
area (45mm*45mm)
20.25 𝑐𝑚2
Sample measurement area
(38mm*25mm)
9.50 𝑐𝑚2
Current 1.00 A
Determination of total force ‘F2’ and pressure from a 5.13kg mass
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𝐹2 = 𝐹0 + 𝑖 ∗ 𝑚 ∗ 𝑔
𝐹2 = 410𝑁 + 32 ∗ 5,13𝑘𝑔 ∗9.81𝑚
𝑠2= 2,020.41𝑁
𝑃 =𝐹
𝐴=
2,020.41𝑁
0.00095𝑚2= 2126747.37𝑃𝑎 = 21.27𝑏𝑎𝑟
𝑀1 = 𝑀2
𝐹1 ∗ 𝑥 + 𝑦 = 𝐹2 ∗ 𝑥
𝑖 =𝐹2
𝐹1=
𝑥+𝑦
𝑥=
484𝑚𝑚
15𝑚𝑚= 32.26
Ratio of the output force to the input force (i)
𝑅𝑇𝑂𝑇 = 𝑅𝐶𝑃/𝑆𝐹 + 𝑅𝑆𝐹 + 𝑅𝑆𝐹/𝐺𝐷𝐿 + 𝑅𝐺𝐷𝐿 +𝑅𝐺𝐷𝐿/𝑆 +𝑅𝑆 +𝑅𝐺𝐷𝐿/𝑆 +𝑅𝐺𝐷𝐿 +𝑅𝑆𝐹/𝐺𝐷𝐿 +𝑅𝑆𝐹 +𝑅𝐶𝑃/𝑆𝐹
𝑅𝑇𝑂𝑇 = 2𝑅𝐶𝑃/𝑆𝐹 + 2𝑅𝑆𝐹 + 2𝑅𝑆𝐹/𝐺𝐷𝐿 + 2𝑅𝐺𝐷𝐿 +2𝑅𝐺𝐷𝐿/𝑆 +𝑅𝑆
As 𝑅𝐺𝐷𝐿 ≈ 0, it is negligible and hence,
𝑅𝑇𝑂𝑇 = 2𝑅𝐶𝑃/𝑆𝐹 + 2𝑅𝑆𝐹 + 2𝑅𝑆𝐹/𝐺𝐷𝐿 +2𝑅𝐺𝐷𝐿/𝑆 +𝑅𝑆
The following total resistance was determined:
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For the reference measurement, the total resistance was determined:
𝑅𝑇𝑂𝑇,𝑅𝑒𝑓. = 𝑅𝐶𝑃/𝑆𝐹 + 𝑅𝑆𝐹 + 𝑅𝑆𝐹/𝐺𝐷𝐿 + 𝑅𝐺𝐷𝐿 +𝑅𝑆𝐹/𝐺𝐷𝐿 +𝑅𝑆𝐹 +𝑅𝐶𝑃/𝑆𝐹
𝑅𝑇𝑂𝑇,𝑅𝑒𝑓. = 2𝑅𝐶𝑃/𝑆𝐹 + 2𝑅𝑆𝐹 + 2𝑅𝑆𝐹/𝐺𝐷𝐿 + 𝑅𝐺𝐷𝐿
As 𝑅𝐺𝐷𝐿 ≈ 0, it is negligible and hence,
𝑅𝑇𝑂𝑇,𝑅𝑒𝑓. = 2𝑅𝐶𝑃/𝑆𝐹 + 2𝑅𝑆𝐹 + 2𝑅𝑆𝐹/𝐺𝐷𝐿
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𝑅𝑇𝑂𝑇 − 𝑅𝑇𝑂𝑇,𝑅𝑒𝑓. = 2𝑅𝐶𝑃/𝑆𝐹 + 2𝑅𝑆𝐹 + 2𝑅𝑆𝐹/𝐺𝐷𝐿 +2𝑅𝐺𝐷𝐿/𝑆 +𝑅𝑆 − (2𝑅𝐶𝑃/𝑆𝐹 + 2𝑅𝑆𝐹 + 2𝑅𝑆𝐹/𝐺𝐷𝐿)
𝑅𝑇𝑂𝑇 − 𝑅𝑇𝑂𝑇,𝑅𝑒𝑓. = 2𝑅𝐺𝐷𝐿/𝑆 + 𝑅𝑆
Sample resistance:
Introduction
Objectives
Theoretical Background
Experimental Settings ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Results ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Conclusions
Appendix
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0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
30% PP 25% PP 20% PP
In p
lan
e R
esis
tivi
ty /
Ωcm
Material
Perpendicular to injectiondirection
Injection Direction
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0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
30% PP 25% PP 20% PP
In p
lan
e C
on
du
ctiv
ity
/ S/
cm
Material
Perpendicular to injection direction
Injection Direction
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Introduction
Objectives
Theoretical Background
Experimental Settings ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Results ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Conclusions
Appendix
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0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
70% graphite-30%PP 75% graphite-25%PP 80% graphite-20%PP
Thro
ugh
-pla
ne
Re
sist
ivit
y /
Ωcm
Materials
4,32
6,44
13,07
21,27
30,02
38,26
[bar]
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0.0000
0.0500
0.1000
0.1500
0.2000
0.2500
0.3000
0.3500
0.4000
70% graphite-30%PP 75% graphite-25%PP 80% graphite-20%PP
Thro
ugh
-pla
ne
Co
nd
uct
ivit
y /
S/cm
Materials
4,32
6,44
13,07
21,27
30,02
38,26
[bar]
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Introduction
Objectives
Theoretical Background
Experimental Settings ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Results ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Conclusions
Appendix
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1. A change from 70% graphite to 80% graphite increases all conductivities measured by a factor of 7 approximately
◦ The mechanical properties were not analyzed in this measurement
2. The injection direction orientation shows 18 to 29% higher electrical conductivity than the perpendicular to injection direction orientation
3. An increase of pressure from 4.32 bar to 38.26 bar shows an improvement on the total conductivity by a factor of 2.2 – 2.5
◦ Due to the reduction of contact resistance
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33 6/11/2014 7:27 PM
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jülich GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
2. Methta, Vial; Smith, Joyce: Review and analysis of PEM fuel cell design and manufacturing; Journal of Power Sources 114 (2003) 32-53
3. Mc Tavish, J.P.: Foundation Electrical Engineering; Prentice Hall International (UK) Ltd. (1996); ISBN: 0-13-309931-8
6/11/2014 7:27 PM 34
35 6/11/2014 7:27 PM
4. Maxfield, Clive: Electrical Engineering, Elsevier Inc.,United States of America (2008); ISBN: 978-1-85617-528-9
5. Prakash, C. Ghosh; Dey Tapobrata; Singdeo, Debanand: Contact resistance between bipolar plate and gas diffusion layer in high temperature polymer electrolyte fuel cells; International Journal of Hydrogen Energy 39 (2014) 987-995
6. Middelman, E.;Kout, W.; Vogelaar, B.;Lenssen, J.; de Waal, E.: Bipolar plates for PEM fuel cells; Journal of Power Sources 118 (2003) 44 – 46
Introduction
Objectives
Theoretical Background
Experimental Settings ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Results ◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
Conclusions
Appendix
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Nr. Name Weights (kg)
Total Weight
(kg)
Force
“F2” (N)
Pressure Reference
Measurement (bar)
Pressure at
sample surface
(bar)
1. 0 0 0 410.00 2.02 4.32
2. 1 0.643 0.643 611.85 3.02 6.44
3. 2 2.648 2.648 1241.26 6.13 13.07
4. 4 5.13 5.13 2020.41 9.98 21.27
5. 4+2 5.13+2.648 7.778 2851.67 14.08 30.02
6. 4+3 5.13+5.143 10.273 3634.90 17.95 38.26
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Injection Direction Perpendicular to injection direction
Material / Data
Resistivity
(Ωcm)
St.
Dev.
Conductivi
ty (S/cm)
St.
Dev.
Resistivit
y (Ωcm)
St.
Dev.
Conductivi
ty (S/cm)
St.
Dev.
70% graphite-
30%PP 0.901 0.121 1.134 0.188 1.168 0.176 0.880 0.162
75% graphite-
25%PP 0.299 0.040 3.404 0.481 0.385 0.052 2.647 0.388
80% graphite-
20%PP 0.130 0.013 7.742 0.751 0.155 0.022 6.579 0.974
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Material 70% graphite-30%PP 75% graphite-25%PP 80% graphite-20%PP
Pressure
(Bar)/Data
Resistivity
(Ωcm) St. Dev.
Resistivity
(Ωcm) St. Dev.
Resistivity
(Ωcm) St. Dev.
4.32 55.18 18.73 30.53 4.64 8.3623 1.3562
6.44 48.10 16.72 26.50 4.27 7.1594 1.0763
13.07 36.21 13.05 19.13 3.10 5.1281 0.6734
21.27 29.93 10.48 15.01 2.21 4.1027 0.5338
30.02 26.91 9.30 13.14 1.84 3.5917 0.4168
38.26 25.04 8.71 12.08 1.65 3.3262 0.3812
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Material 70% graphite-30%PP 75% graphite-25%PP 80% graphite-20%PP
Pressure
(Bar)/Data Conductivity (S/cm)
St.
Dev.
Conductivity
(S/cm) St. Dev.
Conductivity
(S/cm)
St.
Dev.
4.32 0.0194 0.0042 0.0335 0.0053 0.1229 0.0217
6.44 0.0224 0.0050 0.0387 0.0063 0.1429 0.0228
13.07 0.0299 0.0070 0.0536 0.0084 0.1983 0.0265
21.27 0.0360 0.0084 0.0680 0.0096 0.2480 0.0347
30.02 0.0400 0.0092 0.0775 0.0104 0.2826 0.0383
38.26 0.0430 0.0098 0.0842 0.0111 0.3045 0.0357
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