Mass Transfer Enhancement for Improving the Performance of Polymer Electrolyte Fuel Cells

Volume 3 ◽  
2004 ◽  
Author(s):  
P. W. Li ◽  
U. Uysal ◽  
M. K. Chyu
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Electrical Power ◽  
Cell Voltage ◽  
Polymer Electrolyte Fuel Cells ◽  
Transfer Enhancement ◽  
Mass Transfer Enhancement ◽  
Novel Structure ◽  
Conventional Structure

The significance of mass transfer enhancement in polymer electrolyte fuel cells (PEFC) is presented and studied in this work based on experimental investigation. A novel structure of reactant gas distributors in PEFC is proposed for mass transfer enhancement purpose. For the PEFC with novel gas distributors, it is found that the large drop of the cell voltage, generally caused by a weak mass diffusion, is postponed to occur at relatively higher current density even though the same or less amount of air is fed when comparing to a PEFC with gas distributors in conventional structure. As a result, the maximum obtained electrical power in a PEFC and a PEFC stack both are dramatically improved under both free convective and forced convective airflow conditions.

Transients of Polymer Electrolyte Fuel Cell and Hydrogen Tank

2009 ◽  
Author(s):  
Yun Wang ◽  
Xiaoguang Yang
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Dynamic Models ◽  
Cell Voltage ◽  
Polymer Electrolyte Fuel Cells ◽  
Dynamic Responses ◽  
Polymer Electrolyte Fuel Cell ◽  
Electrochemical Double Layer ◽  
The One

This paper seeks to develop 3D dynamic models for polymer electrolyte fuel cells (PEFCs) and hydrogen tanks, respectively. The dynamic model of PEFCs consists of multiple layers of a single PEFC and couples the various dynamic mechanisms in fuel cells, such as electrochemical double-layer discharging/charging, species transport, heat transfer, and membrane water uptake. The one of hydrogen tanks includes a 3D description of the hydride kinetics coupled with mass/heat transport in the hydrogen tank. Transient of fuel cell during step change in current is simulated. Dynamic responses of the cell voltage and heat generation rate are discussed. Hydrogen absorption process in the tank is considered. Temperature, reaction rate and heat rejection in the fuel tank are presented. Efforts are also made to discuss the coupling of these two systems in practice and associated issues.

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.

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.

Mass transfer enhancement of a spiral-like interconnector for planar solid oxide fuel cells

2015 ◽  
Vol 160 ◽  
pp. 954-964 ◽  
Author(s):  
Min Yan ◽  
Pei Fu ◽  
Xiang Li ◽  
Min Zeng ◽  
Qiuwang Wang
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Transfer Enhancement ◽  
Mass Transfer Enhancement
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