dynamic water management studies by means of perforated … · 2014. 11. 17. · schmallenberg st....
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Dynamic Water Management Studies by means of Perforated GDLs and In-situ ESEM Observations
Robert Alink, Dietmar Gerteisen, Christian Sadeler, Christopher Hebling
Fraunhofer Institute for Solar Energy Systems ISE Freiburg, Germany
Diagnostic Tools for Fuel Cell Technologies 24.06.2009, Trondheim
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Overview
Test scope: Examination of the water transportproperties of laser perforated of gas diffusion layers
In-situ single cell experiments and stack experiments
Ex-situ visualizing of water transport in untreated and perforated GDLs in ESEM
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
The Fraunhofer Society58 Institutes - 12 600 Employees – 1.2 Bio € Budget7 Alliances
MikroelectronicsProduction TechnologyInformation and Communication TechnologyMaterials, DevicesLife Sciences
Surface Technology and Photonics
Defense and Security Research
Itzehoe
BerlinGolm
Magdeburg
Hannover
Braunschweig
Bremen
OberhausenDortmund
Duisburg
AachenEuskirchen
SchmallenbergSt. Augustin
IlmenauJena
Dresden
Chemnitz
Würzburg
Erlangen
Pfinztal
DarmstadtKaiserslauternSt. Ingbert
SaarbrückenKarlsruhe
Stuttgart
Freiburg
Freising
Rostock
Teltow
CottbusHalleSchkopau
Paderborn
Nürnberg
Efringen-Kirchen
MünchenHolzkirchen
Leipzig
Itzehoe
BerlinGolm
Magdeburg
Hannover
Braunschweig
Bremen
OberhausenDortmund
Duisburg
AachenEuskirchen
SchmallenbergSt. Augustin
IlmenauJena
Dresden
Chemnitz
Würzburg
Erlangen
Pfinztal
DarmstadtKaiserslauternSt. Ingbert
SaarbrückenKarlsruhe
Stuttgart
Freiburg
Freising
Rostock
Teltow
CottbusHalleSchkopau
Paderborn
Nürnberg
Efringen-Kirchen
MünchenHolzkirchen
Leipzig
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
DevelopmentComponents
Products, PrototypesSystems, Processes
Fraunhofer ISEResearch & Development, Services
ServicesConsulting, Tests
MonitoringQuality Assurance
ResearchMaterialsModellingMethods
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Development of fuel cell systems, stacks and autonomously controlled systems
Characterizing and modelling single cells, stacks and systems
Control and safety technology
Fuel Cell Systems
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
As consequence:water hinders oxygen
diffusion
How can perforation of GDLs help to enhance theperformance?
Water is generated in thecatalyst layer
Water flows throughsmall cavities
Small filled cavitiesmerge to larger cavities
Void space gets filled byliquid water
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
How can perforation of GDLs help to enhance theperformance?
Pressure needed forthrough-plane transportof liquid water is higherthan that for in-planetransport
Water transport channels(WTCs) support thethrough-plane transport
Decrased saturation and increased oxygen
diffusivity
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Investigation of singlecell with an active area of1 cm2
Cathode GDL „under thechannel“ was perforatedby laser treatment
Holes have a diameter of 80 μm and a gap distance of 1 mm
Investigation of single cell
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
forward
backward
* without anode polarization
different operatingconditions
sweep rate 10 mV/s
Dynamic polarisation curves @
show hysteresis effect
Enhancing liquid water transport by laser perforation of a GDL in a PEM fuel cellJournal of Power Sources, Vol 177, Issue 2, 1 March 2008, P 348-354D. Gerteisen, T. Heilmann, C. Ziegler
In-situ characterising of GDL water transport properties
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Potential sweepmeasured with non-modified GDL
Improving the liquid water transport in the GDL
Enhancing liquid water transport by laser perforation of a GDL in a PEM fuel cellJournal of Power Sources, Vol 177, Issue 2, 1 March 2008, P 348-354D. Gerteisen, T. Heilmann, C. Ziegler
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Improving the liquid water transport in the GDL
Potential sweepmeasured with non-modified GDL
Hysteresis knee due to flooding effects
Enhancing liquid water transport by laser perforation of a GDL in a PEM fuel cellJournal of Power Sources, Vol 177, Issue 2, 1 March 2008, P 348-354D. Gerteisen, T. Heilmann, C. Ziegler
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Improving the liquid water transport in the GDL
Enhancing liquid water transport by laser perforation of a GDL in a PEM fuel cellJournal of Power Sources, Vol 177, Issue 2, 1 March 2008, P 348-354D. Gerteisen, T. Heilmann, C. Ziegler
Potential sweepmeasured with non-modified GDL
Hysteresis knee due to flooding effects
Perforated GDL showslowered pore flooding
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Improving the liquid water transport in the GDL
Enhancing liquid water transport by laser perforation of a GDL in a PEM fuel cellJournal of Power Sources, Vol 177, Issue 2, 1 March 2008, P 348-354D. Gerteisen, T. Heilmann, C. Ziegler
Chronoamperometriy
700 400 mV
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Performance improvement ~15%
Improving the liquid water transport in the GDL
Enhancing liquid water transport by laser perforation of a GDL in a PEM fuel cellJournal of Power Sources, Vol 177, Issue 2, 1 March 2008, P 348-354D. Gerteisen, T. Heilmann, C. Ziegler
Chronoamperometriy
700 400 mV
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Improving the liquid water transport in the GDL
Enhancing liquid water transport by laser perforation of a GDL in a PEM fuel cellJournal of Power Sources, Vol 177, Issue 2, 1 March 2008, P 348-354D. Gerteisen, T. Heilmann, C. Ziegler
Chronoamperometriy
600 300 mV
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Performance improvement ~20%
Improving the liquid water transport in the GDL
Enhancing liquid water transport by laser perforation of a GDL in a PEM fuel cellJournal of Power Sources, Vol 177, Issue 2, 1 March 2008, P 348-354D. Gerteisen, T. Heilmann, C. Ziegler
Chronoamperometriy
600 300 mV
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Investigation of fuel cell stack
Air cooled stack
6 cells
Active area of 6 x 31 cm2
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Cell stability at 0.71 A/cm2
Stability test at 0.71 A/cm2 and 63 °C
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Cell stability at 0.71 A/cm2
Stability test at 0.71 A/cm2 and 63 °C
Voltages of outer cellstend to collaps due to flooding
Higher overallperformance
3 times less purging steps
Increased stabilityand performance
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Polarisation curve
Higher Voltage at constant current
Less variation of singlecell-voltage
Increased stabilityand performance
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Chronovoltametry
Increased stabilityand performance
Higher Voltage afterswitching to highercurrent
Lower temperature dueto lower mass transportlosses
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Examination of degradation by freezing water in ESEM
ESEM working in watervapor athomsphere
All 3 phases of waterpossible by adjustingtemperature and pressure
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
bef
ore
Freeze / thaw cycling of GDLs
Examination of degradation by freezing water in ESEM
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
bef
ore
10 x freeze / thaw
afte
r
Freeze / thaw cycling of GDLs
Examination of degradation by freezing water in ESEM
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
bef
ore
10 x freeze / thaw 10 x freeze / thaw
afte
r
Freeze / thaw cycling of GDLs
Freeze / thaw cycling of MEAs
Examination of degradation by freezing water in ESEM
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
bef
ore
10 x freeze / thaw 10 x freeze / thaw 10 x wet / dry
afte
r
Freeze / thaw cycling of GDLs
Freeze / thaw cycling of MEAs
Wet / dry cycling of MEAs as reference
Examination of degradation by freezing water in ESEM
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Liquid water examination in ESEM
ESEM working in watervapor athomsphere
All 3 phases of waterpossible by adjustingtemperature and pressure
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Ex-situ visualization of liquid water breakthrough in ESEM
Water is „sucked“through a porousmembrane and the GDL
Visulization of waterbreakthrough near theGDL surface
800 Pa absolute
1x105 Pa absolute
E-beam
GDL
water
GDLGDL
porous membrane
ESEM
800 Pa
1 °C
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within an untreated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Transportation of water within a perforated GDL
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DIAGNOSTIC TOOLS FOR FUEL CELL TECHNOLOGIES 2009
Summary
Single cell experimentsconsistant with stackexperiments
Significant increase in cellperformance and stabilityachieved
New method found to visualize water transportin GDLs in ESEM