| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2006: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Polymer electrolyte fuel cells (PEFCs) are noticed as an energy conversion system with high efficiency and little environmental contamination. In this research project, it was attempted to use bio-ethanol as fuel for PEFC. Bio-ethanol is a liquid including ethanol obtained by fermentation of saccharide using yeast. In addition, it was attempted to improve the performance of bio-fuel cells, which generate electricity through the metabolizing process of microorganisms such as yeast which is harmless for the human body.
The liquid flow in the anode flow passage of a flat-type direct ethanol PEFC (DEFC) was numerically analyzed by an original thermo-fluid analysis code (GTT code) and also the flow velocity distribution was measured by particle image velocimetry (PIV). Furthermore, the visualization experiment with dye and the liquid constituent analysis by liquid chromatography were carried out. It was confirmed that bi-products which deteriorated the catalytic reaction were accumulated at
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a stagnation point.
A suitable shape of a DEFC flow channel with excellent exhaust ability of by-products and low pressure loss was devised. For reducing the pressure loss by suppressing flow stagnation in the channel, the shape of 180 deg, sharp bend was optimized by numerical flow analysis with a genetic algorithm (GA). As a result, a shape with 33% less pressure loss has been found. Furthermore, the reactive resistance in the originally developed cylindrical PEFC "Power Tube"was measured by an AC impedance meter. It has been found that the reaction resistance when ethanol is used as fuel is much higher than that when hydrogen is used.
The performance of a bio-fuel cell using yeast and sucrose aqueous solution was improved. As a result, one cell having six current collectors (each area is 20 cm2) for each of the anode and cathode has achieved approximately 10 mW at the maximum output power. For practical use, a bio-fuel cell having a bioreactor, in which the solution including yeast in the anode was immobilized, was developed. In this bioreactor, the aqueous solution of sucrose used as fuel was circulated autonomously by the pressure of carbon dioxide gas without a pump, although the generation performance decreased slightly. Furthermore, the proliferative process of immobilized microorganisms was three-dimensionally analyzed by the GTT code, and it has been shown that the proliferative process can be predicted. Less
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