3. ๏ฝ Membrane electrode assembly (MEA)
๏ฝ Gaskets and End plates
๏ฝ Bipolar Plates
6/11/2014 7:27 PM 3
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jรผlich
GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
4. ๏ฝ Distribution of gases,
๏ฝ Prevention of gas leakage,
๏ฝ Separation of the fuel and oxygen/air,
๏ฝ Collection of electrical current produced
๏ฝ Chemical, mechanical and thermal stability
46/11/2014 7:27 PM
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jรผlich
GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
5. 5
Nr. Requirement Target Unit
1 Electrical resistivity ห 0.01 ฮฉ cm
2 Corrosion resistance ห 16 ยตA/cmยฒ
3 Thermal conductivity ห 10 W/mK
4 Compression strength 42 bar
5 Density (Weight/Volume) ห 5 g/cm3
6 Costs ห 0.0045 US$/cmยฒ
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 Jรผlich 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
7. 1. Analysis of Electrical properties of three different
Bipolar plate materials
โฆ 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
76/11/2014 7:27 PM
9. ๏ฝ Resistance depends on:
I. The type of material
II. The length
III. The thickness
IV. The temperature
๏ฝ For a given material at
constant temperature
6/11/2014 7:27 PM 9
3. Mc Tavish, J.P.: Foundation Electrical Engineering; Prentice Hall International (UK) Ltd. (1996); ISBN: 0-13-309931-8
๐น โผ
๐
๐จ
10. ๏ฝ Constant of resistivity (ฯ) takes into account the
type of material:
๐น = ๐
๐
๐จ
๏ฝ Conductivity (ฯ ) reciprocal of resistivity
๐ฎ =
๐
๐น[๐ด]
= ๐บ ๐ฎ = ๐
๐จ
๐
106/11/2014 7:27 PM
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
11. ๏ฝ Pure Graphite 6
โฆ Electrical conductivity
โฆ Thermal conductivity
โฆ sophisticated & costly
processing
โฆ unsuitable for reasons of
stability
1. Electro graphite
2. Carbon โ carbon composite
3. Sheet Metal
4. Flexible graphite foil
5. Graphite polymer composite 6
6/11/2014 7:27 PM 11
๏ฝ Proportion between graphite
and polymer 1:
โฆ 75% - 80% of graphite
โฆ 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
Jรผlich 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 โ 46
12. ๏ฝ Compression molding
๏ฝ Injection molding
๏ฝ Two-component
injection molding
๏ฝ Preform molding
๏ฝ Advantages
โฆ Automated production,
โฆ Short cycle time and
โฆ Accurate size
๏ฝ Disadvantages
โฆ Excessive mold wear
โฆ Limited size of thickness
ratio and
โฆ Could affect conductivity
6/11/2014 7:27 PM 12
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 โ 46
13. ๏ฝ Bulk resistance
โฆ Ohmic resistance of the
component or material
๏ฝ Contact resistance
โฆ Resistance at the interface of
two different surfaces in contact
with each other
๏ฝ Total resistance:
โฆ Contact resistance + bulk
resistance of the individual
components
6/11/2014 7:27 PM 13
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
๐น ๐๐๐ = ๐น ๐/๐ + ๐น ๐/๐ + ๐น ๐ + ๐น ๐ + ๐น ๐
15. 25mm
38mm
2.1mm
Thirty samples made from
three different materials
each in equal number
156/11/2014 7:27 PM
Two different configurations were designed:
โข in-plane and
โข through-plane
16. ๏ฝ Two different orientations:
1. in the injection direction
2. perpendicular to the injection direction
6/11/2014 7:27 PM 16
Parameter Value Unit
Current flow area of
injection direction
orientation
0.525 ๐๐2
Current flow area of
perpendicular to injection
direction orientation
0.798 ๐๐2
Electrical Current 0.85 A
21. ๏ฝ Pressure distribution
analysis
๏ฝ Parameters
6/11/2014 7:27 PM 21
Parameter Value Unit
Reference measurement
area (45mm*45mm)
20.25 ๐๐2
Sample measurement area
(38mm*25mm)
9.50 ๐๐2
Current 1.00 A
22. ๏ฝ Determination of total force โF2โ
and pressure from a 5.13kg mass
6/11/2014 7:27 PM 22
๐น2 = ๐น0 + ๐ โ ๐ โ ๐
๐น2 = 410๐ + 32 โ 5,13๐๐ โ
9.81๐
๐ 2
= 2,020.41๐
๐ =
๐น
๐ด
=
2,020.41๐
0.00095๐2
= 2126747.37๐๐ = 21.27๐๐๐
๐1 = ๐2
๐น1 โ ๐ฅ + ๐ฆ = ๐น2 โ ๐ฅ
๐ =
๐น2
๐น1
=
๐ฅ+๐ฆ
๐ฅ
=
484๐๐
15๐๐
= 32.26
๏ฝ Ratio of the output force
to the input force (i)
32. 1. A change from 70% graphite to 80% graphite
increases all conductivities measured by a factor of
7 approximately
โฆ 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 โ 2.5
โฆ Due to the reduction of contact resistance
326/11/2014 7:27 PM
34. 1. Bendzulla, Anne: Von der Komponente zum
Stack: Entwicklung und Auslegung von HT-PEFC-
Stacks der 5 kW-Klassen; Forschungszentrum
Jรผlich 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. 356/11/2014 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 โ 46