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TERI Information Digest on Energy and Environment
Year : 2002, Volume : 1, Issue : 1
First page : ( 47) Last page : ( 48)
Print ISSN : 0972-6721.

Direct energy conversion

 


[106]Evaluation of a sol-gel derived nafion/silica hybrid membrane for polymer electrolyte membrane fuel cell applications
Miyake N, Wainright JS, and Savinell RF. 2001Sol-gel derived Nafion/silica hybrid-membranes were investigated as a potential polymer electrolyte for direct methanol fuel cell applications. Methanol uptake and methanol permeability were measured in liquid and vapor phase as a function of temperature, methanol vapor activity, and silica content. Decreased methanol uptake from liquid methanol was observed in the hybrid membranes with silica contents of 10 and 21 wt%. The hybrid membrane with silica content of »20 wt% showed a significant lower methanol permeation rate when immersed in a liquid methanol-water mixture at 25 ºC and 80 ºC. Methanol uptake from the vapour phase by the hybrid membranes appear similar to that of unmodified Nafion. Methanol diffusion coefficients, as determined from sorption experiments, significantly lower in the hybrid membranes than in unmodified Nafion. However, in direct permeation experiments, significantly lower methanol vapor permeability was seen only in the hybrid membranes with silica content of »20 wt%. Based on these results, Nafion/silica hybrid membranes with high silica content have potential as electrolytes for direct methanol fuel cells operating either on liquid or vapour-feed fuels.
(10 figures, 23 references)
Journal of The Electrochemical Society148(8):A905-A909
Ernest B. Yeager Center for Electrochemical Sciences and the Department of Chemical Engineering,
Case Western Reserve University, Cleveland, Ohio 44106–7217, USA
<miyake.nc@om.asahi-kasei.co.jp>

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[107]A solid oxide fuel cell using an exothermic reaction as the heat source
Hibino T, Hashimoto A, Inoue T, Tokuno J, Yoshida S, Sano M. 2001Performance of a single-chamber solid oxide fuel cell was evaluated using a 0.15 mm thick SDC (Sm-doped ceria) electrolyte together with a 30 wt% SDC-Ni anode and a Sm0. 5Sr0. 5CoO3 cathode at heating temperatures below 500 °C in a flowing mixture of butane and air. A large quantity of reaction heat, which was evolved by the partial oxidation of butane by oxygen at the anode, caused a temperature rise of more than 100 ºC at the anode, followed by thermal conduction to the cathode through the electrolyte. Simultaneously, the cell generated a large electromotive force of ca 900 mV between the two electrodes. The resulting peak power density reached 245, 180, 105, and 38 m W/cm2 at heating temperatures of 450, 400, 350, and 300 ºC, respectively. The comparison of the butane fuel with the other hydrocarbon fuels showed that the fuel cell performance became enhanced, especially at reducing temperatures, as the carbon number of the hydrocarbon increased, and the chain structure was branched.
(10 figures, 3 tables, 34 references)
Journal of The Electrochemical Society148(6):A544-A549
National Industrial Research Institute of Nagoya,
Nagoya 462 8510, Japan

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