Polymer electrolyte fuel cells, which have been developed for mobile equipment, are mainly direct methanol fuel cells (DMFC). From the standpoint of safety to a human body, it is desirable to use ethanol as fuel. In order to improve the performance of direct ethanol fuel cells (DEFC), it is necessary to investigate the fuel flow pattern in the anode flow channel with many sharp turn corners in the fuel cell, and to improve the channel shape. So, in this study, the velocity distribution of the water flow in a micro-channel was numerically analyzed using the authors' GTT code and the calculated results were verified by the velocity measurement with a line LDV system. For reducing the pressure loss in consideration of the suppression of flow stagnation in the channel, it was attempted to optimize the sharp turn corner shape by three-dimensional numerical flow analysis with a genetic algorithm (GA) and a shape with less pressure loss was found.

Experiments of micro-flow control and micropump conducted by applying electric fields on the flow through a porous membrane have clarified that only NaCl solution in water is effective for the control of micro-flow among the liquids examined but KCl solution and a colloidal dispersion of polystyrene latex particles in water as well as NaCl solution are good as working fluids for the micropump. Although the applied voltages are less than 10 V, performance of the present micropump is found belonging to the highest class in the past methods. Effects of electro-osmosis, electrophoresis and absorption were discussed about whether or not they may become causes of the present phenomena and it is concluded that absorption is most possible as a cause. The colloidal dispersion of polystyrene latex particles is thought to be a good working liquid, because it provides the flow rate proportional to the applied voltage without generating any bubble of by-product.

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