Polymer Electrolyte Fuel Cells With Porous Materials as Fluid Distributors and Comparisons With Traditional Channeled Systems

2004 ◽  
Vol 126 (3) ◽  
pp. 410-418 ◽  
Author(s):  
S. M. Senn ◽  
D. Poulikakos
Keyword(s):  
Fuel Cells ◽  
Polymer Electrolyte Fuel Cells ◽  
Three Dimensions ◽  
Porous Flow ◽  
Higher Power ◽  
Current Densities ◽  
Flow Configurations ◽  
Novel Concept ◽  
The Impact ◽  
Power Densities

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 a number of known performance hindering drawbacks. A thorough single-phase model, including the conservation of mass, momentum, energy, species, and electric current, using Butler-Volmer kinetics, 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. Another advantage of porous flow distributors is the potential for higher power densities and reduced stack weight.

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.

Platinum-Free Catalysts for Alkaline Polymer Electrolyte Fuel Cells

2014 ◽  
Vol 775-776 ◽  
pp. 512-516 ◽  
Author(s):  
Elen Leal da Silva ◽  
P.S. Correa ◽  
F. de Oliveira ◽  
A. El Sheikh ◽  
C. Radtke ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Electroless Deposition ◽  
Reduction Method ◽  
Polymer Electrolyte Fuel Cells ◽  
Synthesis Methods ◽  
Acidic Media ◽  
Ni Catalysts ◽  
Current Densities ◽  
Alkaline Polymer Electrolyte

Platinum is known as the best catalyst for fuel cells reactions, because it presents the best catalytic activity and stability, mainly in acidic media. However, due to the high cost of platinum and its lower availability, the development of platinum-free catalysts for Alkaline Polymer Electrolyte Fuel Cells has been proposed. This work aims to compare catalysts characteristics obtained from two different synthesis methods. Ni catalysts were obtained by the impregnation/reduction method and by electroless deposition. The morphology of the electro-catalysts obtained were characterized by SEM-EDS and the electrochemical behavior was evaluated by Cyclic Voltammetry. And the composition of the catalysts obtained by the impregnation/reduction method was analyzed by Rutherford Backscattering Spectroscopy. The results obtained showed that the catalyst elaborated by the impregnation/reduction method developed higher current densities values than the catalyst elaborated by electroless deposition.

scholarly journals Stacking efficiency of terrestrial Plant-Microbial Fuel Cells growing Ocimum basilicum and Origanum vulgare

2020 ◽  
Vol 181 ◽  
pp. 01004
Author(s):  
Kristopher Ray S. Pamintuan ◽  
Arnie Jantzen G. Ancheta ◽  
Shaina Marie T. Robles
Keyword(s):  
Fuel Cells ◽  
Microbial Fuel Cells ◽  
Ocimum Basilicum ◽  
Origanum Vulgare ◽  
Apparent Loss ◽  
Higher Power ◽  
In Series ◽  
Harvesting Process ◽  
Power Densities ◽  
Viable Method

Plant-Microbial Fuel Cells (PMFCs) are an emerging type of renewable energy that generates an electric current through the consumption of rhizodeposits by exoelectrogenic bacteria that lives in the rhizosphere of the plant. Since the plant is not harmed by the energy-harvesting process, PMFC technology has the potential to simultaneously produce food (biomass) and generate electricity. As of now, power densities of PMFCs have remained low and commercialization is not yet possible. To achieve higher power densities, the stacking behaviour of PMFCs needs to be studied. In this study, several cells growing Ocimum basilicum (basil) and Origanum vulgare (oregano) were constructed and evaluated. Upon stacking, it was shown that the constructed PMFCs did indeed behave like batteries, where the voltage of cells connected in series are additive, and that the voltage of cells connected in parallel are constant. The actual values of voltage of stacked cells are similar to the expected value (α=0.05). Cumulative stacking tests revealed that there is no apparent loss in voltage upon stacking up to 9 cells growing O. basilicum. Further computation of power and power densities have proven that stacking is a viable method of amplifying electricity generation in PMFCs, as both increased with increasing number of cells connected in series.

An empirical examination of firm financial performance along dimensions of supply chain resilience

2017 ◽  
Vol 40 (3) ◽  
pp. 254-269 ◽  
Author(s):  
Xun Li ◽  
Qun Wu ◽  
Clyde W. Holsapple ◽  
Thomas Goldsby
Keyword(s):  
Supply Chain ◽  
Financial Performance ◽  
Three Dimensions ◽  
Empirical Examination ◽  
Content Type ◽  
Supply Chain Resilience ◽  
Critical Dimensions ◽  
Firm Financial Performance ◽  
Supply Chain Agility ◽  
The Impact

Purpose This paper aims to investigate the impact of three critical dimensions of supply chain resilience, supply chain preparedness, supply chain alertness and supply chain agility, all aimed at increasing a firm’s financial outcomes. In a turbulent environment, firms require resilience in their supply chains to prepare for potential changes, detect changes and respond to actual changes, thus providing superior value. Design/methodology/approach Using survey data from 77 firms, this study develops scales for preparedness, alertness and agility. It then tests their hypothesized relationships with a firm’s financial performance. Findings The results reveal that the three dimensions of supply chain resilience (i.e. preparedness, alertness and agility) significantly impact a firm’s financial performance. It is also found that supply chain preparedness, as a proactive resilience capability, has a greater influence on a firm’s financial performance than the reactive capabilities including alertness and agility, suggesting that firms should pay more attention to proactive approaches for building supply chain resilience. Originality/value First, this study develops a comparatively comprehensive definition for supply chain resilience and explores its dimensionality. Second, this study provides empirically validated instruments for the dimensions of supply chain resilience. Third, this study is one of the first to provide empirical evidence for direct impact of supply chain resilience dimensions on a firm’s financial performance.

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