Flow Distribution Uniformity Evaluation in kWRange Direct Methanol Fuel Cell StackYuta Nakano DOI: 10.1615/IHTC15.fcl.009078 SCHLÜSSELWÖRTER: Fuel cell, Energy conversion and storage, DMFC, Pressure drop, Flow distribution. AbstraktThis paper describes evaluation of flow distribution uniformity in DMFC stack. The DMFC stack has 70 cells with different manifold crosssection area of 500mm2 or 1500mm2. Two flow patterns of Uconfiguration and Zconfiguration are used. Bipolar plate active area is 180cm2 with 30 serpentine channels. Channel is 400mmlong with crosssection area of 0.6875mm2. We performed flow network analysis of DMFC by using manifold flow model combined with cell channel flow. Cell channel flow is modeled by HagenPoiseuille equation. Manifold flow is modeled by mechanical energy conservation equation. Different flow rates are considered 180L/min or 360L/min. Case.1: Uconfiguration, 180L/min, 500mm2, Case.2: Uconfiguration, 360L/min, 500mm2, Case.3: Zconfiguration, 360L/min, 500mm2, Case.4: Uconfiguration, 360L/min, 1500mm2. As flow rate increased from 180L/min to 360L/min, turbulent flow effect in manifold increases. Pressure drop in manifold of case.2 is about 3.8 times larger than that of case.1. As a result, serious nonuniform flow distribution happens in case.2. In comparison between Zconfiguration and Uconfiguration, pressure drop in manifold of case.3 is lower than that of case.2. Zconfiguration is more desirable than Uconfiguration. As manifold crosssection area increasing to 1500mm2 in case.4, pressure drop in manifold of case.4 becomes about oneeighth of that of case.2, which results in more uniform flow distribution. In summary, large pressure drop in manifold is caused by turbulent flow resulting in more serious nonuniform flow distribution in Uconfiguration. Zconfiguration helps to reduce pressure drop in manifold and nonuniform flow distribution for each cell. Manifold crosssection area also has significant effect on flow distribution uniformity. 

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