Katie S. HoweCentre for Hydrogen and Fuel Cell Research
SOFC Research group
www.fuelcells.bham.ac.ukwww.hydrogen-wm-scratch.info
Dynamic Performance of Micro-Tubular Fuel Cells
Overview Starting Point
– Fuel cells– Status of dynamic performance
research Experimental Work Results Conclusions Next Steps
Starting Point: Fuel Cells Change
electrochemical energy into useful electricity
Like a battery, but not limited by how much fuel they can hold
Starting Point: Fuel Cells
mSOFCs– Tubular– Better thermal
shock resistance
– Fewer issues with sealing
Starting Point: Research Status Load-following capability is vital for most
real-world applications
In the literature: Many papers on steady-state performance Some modelling work on dynamic
behaviour [1-3]
...but hardly any experimental results
[1] Nehter, P., 2006, Journal of Power Sources, 157(1), pp. 325-334.[2] Ota, T., Koyama, M., Wen, C. J., Yamada, Y., and Takahashi, H., 2003, Journal of Power Sources, 118(1-2), pp. 430-439.[3] Serincan, M. F., Pasaogullari, U., and Sammes, N. M., 2009, Journal of Power Sources, 194(2), pp. 864-872.
Starting Point: Research Status Thermal transport time dominates dynamics[4]
Readjustment time independent of step size[5]
Undershooting of voltage when current rises[5]
– Size of undershoot related to step size
[4] Bhattacharyya, D., and Rengaswamy, R., 2009, "A Review of Solid Oxide Fuel Cell (SOFC) Dynamic Models," Ind. Eng. Chem. Res., 48(13), pp. 6068-6086[5] Achenbach, E., 1995, "Response of a solid oxide fuel cell to load change," Journal of Power Sources, 57(1-2), pp. 105-109.
Experimental Work - Method Single cells made to in-house techniques[6]
– Operated at 750C– Fuel: 20ml/minute of pure hydrogen
SolartronTM analytical 1400 Cell Test System–Apply sets of square pulses of current
Paper submitted[7] with precise details[6] Dhir, A., 2008, "Improved Microtubular Solid Oxide Fuel Cells," PhD Thesis, University of Birmingham, [7] Howe, K. S.; Kendall, K., Transient Performance of Micro-tubular Solid Oxide Fuel Cells. Journal of Fuel Cell Science and Technology 2010, .Paper Accepted – awaiting editorial changes
Conclusions Short re-adjustment time of <0.5s is
independent of step size– Agreement with models in the literature
No under-shooting of voltage on the change– Suggests thermal transport is better than
expected in these tubes
Next Steps Combination of cells into small stacks
– Higher powers– Dynamic performance testing of stacks
Effects of changing to a hydrocarbon fuel on transient performance
Acknowledgements
With thanks to...
My supervisors: Kevin Kendall and Stephen Decent
My sponsors: RCUK and EADS Innovation Works