New Conceptual Gas Distributor With Mass Transfer Enhancing Function in Polymer Electrolyte Fuel Cells

2004 ◽  
Author(s):  
P. W. Li ◽  
S. P. Chen ◽  
M. K. Chyu
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Gas Flow ◽  
Flow Fields ◽  
Pem Fuel Cells ◽  
Polymer Electrolyte Fuel Cells ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Sharp Drop

A new conceptual structure of the gas distributors in polymer electrolyte fuel cells (PEFC) or proton exchange membrane (PEM) fuel cells is developed in this work. Basically, instead of partitioned channels and non-interrupted walls, the proposed new gas distributors make use of discretized elements as the current collector in the flow fields, which can help to enhance the mass transfer in the gas flow fields while maintaining the function of transmitting current out of the fuel cell. Experimental operation without external humidification of the reactant gases for single PEM fuel cells and cell stacks using conventional and the currently presented gas distributors were conducted for comparison and verification. It was found that the maximum operational cell current, beyond which there is a sharp drop of the cell voltage, could be significantly improved when using the currently proposed gas distributors and the same membrane-electrode-assembly (MEA) sheets. Correspondingly, the output electrical power can have at least 11 percent increment for the operation with free-convective airflow and around 50 percent increment for the operation with forced convective airflow.

Porous Materials as Fluid Distributors in Polymer Electrolyte Fuel Cells: A Computational Performance Analysis

2003 ◽  
Author(s):  
S. M. Senn ◽  
D. Poulikakos
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Reaction Rates ◽  
Flow Fields ◽  
Polymer Electrolyte Fuel Cells ◽  
Three Dimensions ◽  
Strong Argument ◽  
Computational Performance ◽  
The Impact

Commonly used ribbed flow-fields such as parallel and serpentine flow-fields in polymer electrolyte fuel cells (PEFC) exhibit limited mass transfer to the part of the diffusion and catalyst layer which is not covered by flow channels, leading to a considerably reduced reactant concentration and increased overpotential losses under the current collector shoulders. In this study, a novel concept is investigated, according to which the traditional ribbed flow delivery systems are replaced with permeable porous fluid distributors, which circumvent drawbacks such as those mentioned earlier. A complex mathematical model, including the conservation of mass, momentum, energy, species and electric current, using Butler-Volmer kinetics for electrochemical reaction rates, is numerically solved in three dimensions, to investigate the impact of different flow configurations on the performance of hydrogen fuel cells. It is found that cells with porous gas distributors generate substantially higher current densities and therefore are more advantageous with respect to mass transfer. Reduction in stack weight is another strong argument for using porous flow distributors in future applications.

scholarly journals Investigation of Nanographene Produced by In-Liquid Plasma for Development of Highly Durable Polymer Electrolyte Fuel Cells

2018 ◽  
Vol 4 (4) ◽  
pp. 65 ◽  
Author(s):  
Vladislav Gamaleev ◽  
Kengo Kajikawa ◽  
Keigo Takeda ◽  
Mineo Hiramatsu
Keyword(s):  
Power Generation ◽  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Amorphous Carbon ◽  
Carbon Nanostructures ◽  
Polymer Electrolyte Fuel Cells ◽  
Membrane Electrode ◽  
Catalytic Layer ◽  
Pt Nanoparticle ◽  
Durable Polymer

Recently, polymer electrolyte fuel cells (PEFCs) are attracting a lot of attention owing to their small size and relatively low working temperature (below 80 °C), which enables their usage in automobiles and household power generation. However, PEFCs have a problem with decreased output caused by corrosion of amorphous carbon, which is commonly used as a catalytic carrier. This problem could be solved by the usage of carbon nanostructures with a stronger crystal structure than amorphous carbon. In this work, nanographene supported by Pt nanoparticles was synthesized and examined for possible applications in the development of PEFCs with increased durability. Nanographene was synthesized by in-liquid plasma generated in ethanol using alternating current (AC) high voltage. A membrane electrode assembly (MEA) was constructed, where Pt nanoparticle-supported nanographene was used as the catalytic layer. Power generation characteristics of the MEA were evaluated and current density for the developed MEA was found to be approximately 240 mA/cm2. From the electrochemical evaluation, it was found that the durability of Pt nanoparticle-supported nanographene was about seven times higher than that of carbon black.

Fabrication and Performance Evaluation of Miniaturized Proton Exchange Membrane (PEM) Fuel Cells

2003 ◽  
Author(s):  
Tao Zhang ◽  
Pei-Wen Li ◽  
Qing-Ming Wang ◽  
Laura Schaefer ◽  
Minking K. Chyu
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Free Convection ◽  
Current Density ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Cathode Side ◽  
Ohmic Loss ◽  
Fuel Cell Performance

Two types of miniaturized PEM fuel cells are designed and characterized in comparison with a compact commercial fuel cell device in this paper. One has Nafion® membrane electrolyte sandwiched by two brass bipolar plates with micromachined meander-like gas channels. The cross-sectional area of the gas flow channel is approximately 250 by 250 (μm). The other uses the same Nafion® membrane and anode structure, but in stead of the brass plate, a thin stainless steel plate with perforated round holes is used at cathode side. The new cathode structure is expected to allow oxygen (air) being supplied by free-convection mass transfer. The characteristic curves of the fuel cell devices are measured. The activation loss and ohmic loss of the fuel cells have been estimated using empirical equations. Critical issues such as flow arrangement, water removing and air feeding modes concerning the fuel cell performance are investigated in this research. The experimental results demonstrate that the miniaturized fuel cell with free air convection mode is a simple and reliable way for fuel cell operation that could be employed in potential applications although the maximum achievable current density is less favorable due to limited mass transfer of oxygen (air). The relation between the fuel cell dimensions and the maximum achievable current density is also discussed with respect to free-convection mode of air feeding.

scholarly journals Computational Chemistry in Proton Exchange Membrane for Polymer Electrolyte Fuel Cells

MEMBRANE ◽  
2007 ◽  
Vol 32 (2) ◽  
pp. 89-94
Author(s):  
Michihisa Koyama ◽  
Kenji Sasaki ◽  
Hideyuki Tsuoi ◽  
Nozomu Hatakeyama ◽  
Akira Endou ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Computational Chemistry ◽  
Polymer Electrolyte ◽  
Proton Exchange Membrane ◽  
Polymer Electrolyte Fuel Cells ◽  
Proton Exchange ◽  
Exchange Membrane
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