Direct liquid fuel cells represent an interesting alternative to conventional hydrogen fuel cell technology. A novel analytical method for the monitoring of direct liquid fuel cells is presented. Employing a combination of chronoamperometric, gravimetric and Raman spectroscopic measurements this method allows a straightforward determination of the Faradaic efficiency of a fuel cell. This method was applied in a proof of concept study analysing the operational behaviour of a direct methanol fuel cell. A very low Faradaic efficiency was found for the fuel cell under study. This was attributed to loss of methanol from the fuel mixture due to methanol crossover, stripping of methanol by carbon dioxide as well as evaporation. It is known from the literature that a fuel change from methanol towards higher alcohols and other hydrocarbons can help to mitigate the effects of these loss processes. However, the behaviour of such alternative fuels and their mixtures in an operating fuel cell and hence the performance of the fuel cell depends at least in part on the intermolecular interactions present in those fuel mixtures. Therefore, the intermolecular interactions in binary and ternary mixtures of potential candidates for alternative fuels were investigated in the main part of this thesis. Studies on the intermolecular interactions in binary mixtures of acetone with ethanol and 1-butanol showed a tendency for self association of both compounds albeit in different concentration ranges. It was further found that the alkyl chain length of the alcohols did not have a significant effect on the intermolecular interactions in the binary and ternary mixtures. Further, the behaviour of the ternary mixture was found to closely resemble the effects found in the individual binary mixtures. Finally, binary mixtures of dimethyl sulfoxide (DMSO) and different alcohols did not show self association. It was rather found that alcohol molecules inserted into chains of DMSO molecules eventually leading to the formation of alcohol-DMSO dimers.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:655664 |
| Date | January 2014 |
| Creators | Zehentbauer, Florian |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=225964 |
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