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SUMMARYIn this study, we present a rigorous mathematical model, to treat prediction and analysis of proton exchange membrane fuel cells gas concentration and current density distribution in mass transfer area and chemical reaction area performed in 3-D geometry. The model is based on the solution of the conservation equations of mass, momentum, species, and electric current in a fully integrated finite-volume solver using the CFDRC commercial code. The influences of fuel cell performance with two kinds of flow channel pattern design are studied. The gas concentration of the straight flow pattern appears excessively nonuniform, resulting in a local concentration polarization. On the other hand, the gas concentration is well distributed for the serpentine flow pattern, creating a better mass transfer phenomena. The performance curves (polarization curves) are also well correlated with experimental data.

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This study investigates the evaporation of sessile drop comprising ethanol and water mixture on horizontal poly methyl methacrylate surface. The contact angle (h) and contact radius (R) of ethanolwater mixture drop are recorded with time, considering the impacts of presence of ethanol. With excess ethanol, the drop evaporation is principally controlled by a phase in which both the contact angle and contact radius are falling. A diffusional model assuming linear relation between contact radius and time is proposed as h ¼ eR -3 +cR -1 , where e and c denote fitting coefficients. This model correlates with the experimental data.

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