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

ResultsTransient behaviour:

Results

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

Thank you!Thank you!

www.fuelcells.bham.ac.uk

Any questions?Any questions?