Typical Proton Exchange Membrane Research Articles

Pressure losses in laminar flow through serpentine channels in fuel cell stacks

The pressure losses in the flow distributor plate of the fuel cell depend on the Reynolds number and geometric parameters of the small flow channels. Very little information has been published on the loss coefficients for laminar flow. This study reports a numerical simulation of laminar flow though single sharp and curved bends, 180° bends and serpentine channels of typical fuel cell configurations. The effect of the geometric parameters and Reynolds number on the flow pattern and the pressure loss characteristics is investigated. A three-regime correlation is developed for the excess bend loss coefficient as a function of Reynolds number, aspect ratios, curvature ratios and spacer lengths between the channels. These have been applied to calculate the pressure drop in typical proton-exchange membrane fuel cell configurations to bring out the interplay among the important geometric parameters.

Investigation of PEM type direct hydrazine fuel cell

Hydrazine was examined as a fuel in a direct-liquid-fueled fuel cell employing proton exchange membrane (PEM) for the electrolyte. Hydrazine showed better performance than methanol in the direct fuel cell; the cell using hydrazine gave voltage twice as high as that using methanol in the low-current density region. The I– V characteristics were drastically changed depending on the surface area of the anode catalyst. Compositions of the exhaust materials from each electrode were analyzed in order to investigate the reaction that occurred at the electrodes. The analysis revealed that the catalytic decomposition reaction of hydrazine proceeded further than the electro-oxidation reaction on the anode side using a high specific surface area catalyst. The crossover of hydrazine and ammonia through the PEM was confirmed and the reduction of the hydrazine crossover is important in developing further high performance.

Recent progress in performance improvement of the proton exchange membrane fuel cell (PEMFC)

Research activities to improve the performance of the low platinum loading hydrogen–air proton exchange membrane fuel cell (PEMFC) operating at atmospheric pressure are described. Pore-forming additives, new types of proton exchange membranes, and higher activity platinum-on-carbon electrocatalysts have been used in low platinum loading gas diffusion electrodes (GDEs) and Membrane–electrode assemblies (MEAs) developed at this center. A method for the fabrication of an integrated GDE and light weight gas flow-field is described. As a result, a three-fold improvement in PEMFC performance at the same platinum loading has been achieved.

Proton-conducting membrane composed of sulfonated polystyrene microspheres, poly(vinylpyrrolidone) and poly(vinylidene fluoride)

A new type of proton exchange membrane (PEM) consisting of polystyrene sulfonic acid (PSSA) latexes, polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP) has been prepared. The PEM can attain 10 −2 S/cm of the proton conductivity at room temperature, which is greater than what Nafion®-117 offers. An investigation into the morphology and thermal behaviour of the resulting tri-component matrixes has been carried out. The results propose the possibility that PSSA–PVP and PVDF–PVP are the two types of Lewis acid–base pairs existing in the matrixes. The acid–base interactions play a role in facilitating proton transport as well as maintaining dimensional stability of the membrane in hydrated state.

Pocket-size PEMs

A recent study by Joan Ogden at Princeton University’s Center for Energy and Environmental Studies tabulated a range of published estimates for the manufacturing costs of mass-produced auto fuel cell systems. The banded-structure membrane fuel cell, from Fraunhofer ISE, draws off voltage at the endplates through an integrated series connection that ties together individual cells. The typical proton exchange membrane (PEM), fuel cell consists of a series of stacked individual cells, with each cell composed of a flow field plate and a membrane electrode assembly. An air breather PEM fuel cell from DCH Technology distributes hydrogen to the flow fields through a central sleeve, while air at atmospheric pressure comes in through the sides. One of the benefits of Manhattan Scientifics’ circuit board approach is the ability of an electrode to act as a ‘preferential molecular filter’. Fraunhofer Institute scientists have been at work on a banded-structure membrane fuel cell. This device holds five-unit cells on a single plate connected as a series circuit.