benchmarking the fuel cell stack compression process · pdf filebenchmarking a fuel cell stack...
TRANSCRIPT
![Page 1: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/1.jpg)
Benchmarking a fuel cell stack compression process
Mussawar Ahmad, [email protected]
Academic Supervisors
Prof Robert Harrison, Automation Systems Group, Warwick University
Dr James Meredith, Sheffield University
Industrial Supervisors
Dr Axel Bindel, HSSMI
Dr Ben Todd, Managing Director, Horizon Fuel Cells UK
![Page 2: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/2.jpg)
• Background
• Compression• Importance
• Literature values
• Spring equivalent model
• Horizon fuel cell compression system performance
• Conclusion
• Proposed further work
Overview
![Page 3: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/3.jpg)
Background
• Supporting Horizon Fuel Cell UK with fuel cell manufacturing
• Developing assembly methods and processes
• Three critical assembly processes identified• Alignment
• Sealing
• Compression
![Page 4: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/4.jpg)
Assembly process criticalities
![Page 5: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/5.jpg)
1. Magnitude• GDL - Mass transport vs. ohmic losses
• Sealing
• Mechanical stresses
2. Homogeneity• Hotspots
Importance of Fuel Cell Compression
Cell Voltage (V)
Cell Current (A)
Excessive and insufficient compression
Ohmic losses Mass transport losses
Activation losses
![Page 6: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/6.jpg)
• GDL Compression ratio:
𝐺𝐷𝐿 𝑂𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠
𝑂𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝐺𝐷𝐿 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠
Literature compression ratios
• Trendline – coefficient of determination – 0.92
• Useful tool to help fuel cell researchers identify a ballpark figures for GDL compression
• Porosity and PTFE loading also do need to be considered
![Page 7: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/7.jpg)
Spring equivalent model
• Gaskets sit parallel to GDL• Effect gaskets have on GDL compression
can be estimated• Identify force required to reach
compression ratio
Ft = total forceAGDL = SA GDLEGDL = YM GDLAg = SA gasketEg = YM Gasket
CR = GDL compression ratioa = ratio of gasket thickness over GDL
thickness
• BUT, some fuel cells use incompressible gaskets…
• AND, how does this translate to stack?...
𝑙𝑔
![Page 8: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/8.jpg)
• Horizon Fuel Cells UK designed a fuel cell compression system
• Compression characteristics are tested
• Typical methodologies for compression characteristic assessment:• FE Modelling
• Piezoresistive arrays
• Pressure sensitive films
Fuel Cell Compression System
![Page 9: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/9.jpg)
Methodology
Cut compression film to size
Place a film between each cell
in 4 cell stack
Apply compressive force
Wait 1 minute to settle
Reapply forceWait 1 minute to
settleRemove filmsScan films
Use MATLAB code to assess
compression
Repeat at a range of compressive
forces
• MATLAB code converts grayscale scan of film to contour plot
• 3 colour contour to make data easier to visualise
• Local averaging carried out so non-useful data is lost
![Page 10: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/10.jpg)
Results and Discussion
10MPa 20MPa 30MPa
• Non-uniform compression• CoV through z-axis does not exceed 10%• Good symmetry through y-axis• Non-symmetry through x-axis• Could be due to:
• Compression system calibration• Component manufacturing tolerances• Stack/cell assembly tolerances
Applied Compression (MPa) 10 20 30
Mean compression experienced by films
(MPa) 1.90 3.06 4.33
Mean CoV(x-y) 0.34 0.18 0.27
CoV (z) 0.09 0.05 0.01
Average error (%) 8.28 11.02 16.17
GDL Compression Ratio (%) 88 79 70
![Page 11: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/11.jpg)
Conclusion
• Optimal fuel cell compression is important • Potential for cheap and easy maximisation of fuel cell
performance • Increase stack life
• BUT• Compression methods need to be optimised• Assembly processes need more rigour
• Methodology for fuel cell researchers:1. Estimate optimal CR based on literature values2. Use spring equivalent model to estimate required force 3. Use compression system to apply force
![Page 12: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/12.jpg)
• Develop in process QC for ensuring uniform compression at the required magnitude
• Develop methods for testing the alignment and sealing of fuel cells
• Design a fuel cell assembly layout which accommodates• Product variants
• Product traceability i.e. documentation of product birth history
• Volume scale up
Further Work
![Page 13: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/13.jpg)
Questions
Mussawar Ahmad, [email protected]
Academic Supervisors
Prof Robert Harrison, Automation Systems Group, Warwick University
Dr James Meredith, Sheffield University
Industrial Supervisors
Dr Axel Bindel, HSSMI
Dr Ben Todd, Managing Director, Horizon Fuel Cells UK
![Page 14: Benchmarking the fuel cell stack compression process · PDF fileBenchmarking a fuel cell stack compression process Mussawar Ahmad, WMG mussawar.ahmad@warwick.ac.uk Academic Supervisors](https://reader033.vdocument.in/reader033/viewer/2022042611/5aba62847f8b9a441d8b8ff9/html5/thumbnails/14.jpg)
References
Mason, T.J., et al., Effect of clamping pressure on ohmic resistance and compression of gas diffusion layers for polymer electrolyte fuel cells. Journal of Power Sources, 2012. 219: p. 52-59
Wen, C.-Y., Y.-S. Lin, and C.-H. Lu, Experimental study of clamping effects on the performances of a single proton exchange membrane fuel cell and a 10-cell stack. Journal of Power Sources, 2009. 192(2): p. 475-485
Lee, S.-J., C.-D. Hsu, and C.-H. Huang, Analyses of the fuel cell stack assembly pressure. Journal of Power Sources, 2005. 145(2): p. 353-361.
Lee, W.-k., et al., The effects of compression and gas diffusion layers on the performance of a PEM fuel cell. Journal of power sources, 1999. 84(1): p. 45-51.
Xing, X.Q., et al., Optimization of assembly clamping pressure on performance of proton-exchange membrane fuel cells. Journal of Power Sources, 2010. 195(1): p. 62-68.
Montanini, R., G. Squadrito, and G. Giacoppo, Measurement of the clamping pressure distribution in polymer electrolyte fuel cells using piezoresistive sensor arrays and digital image correlation techniques. Journal of Power Sources, 2011. 196(20): p. 8484-8493.
Gatto, I., et al., Influence of the bolt torque on PEFC performance with different gasket materials. International Journal of Hydrogen Energy, 2011. 36(20): p. 13043-13050
Lin, P., P. Zhou, and C.W. Wu, A high efficient assembly technique for large PEMFC stacks. Journal of Power Sources, 2009. 194(1): p. 381-390