Numerical Simulation of a Fluidic Oscillator for Water Removal Enhancement in PEM Fuel Cell

2008 ◽  
Author(s):  
S. H. Tseng ◽  
Y. T. Yang ◽  
J. Allen ◽  
S. L. Yang
Keyword(s):  
Fuel Cell ◽  
Gas Flow ◽  
Water Drop ◽  
Polymer Electrolyte Membrane ◽  
Water Removal ◽  
Acoustic Vibrations ◽  
Flow Rates ◽  
Fluidic Oscillator ◽  
Electrolyte Membrane ◽  
Low Temperature Fuel Cells

The fluidic oscillator is one solution to the problems of water management of the Polymer Electrolyte Membrane Fuel Cell (PEMFC). In low temperature fuel cells such as the PEMFC, liquid water is produced as a byproduct. At low gas flow rates, the water produced has a tendency to plug the reactant supply channels. When the channels are plugged, reactant supply to the catalyst sites is prohibited and results in fuel cell failure. One proposed method of removing a water drop is to oscillate the drop near its natural frequency in order to free it from the substrate. A variety of methods for oscillating the drop are available including mechanical vibrations, acoustic vibrations and flow pulsations. It is the latter method, i.e., use of the fluidic oscillator that is investigated in this study. The purpose of this paper is to use the experimental and numerical techniques to study and simulate a fluidic oscillator so that detail of flow physics inside the oscillator can be realized. Method on how to use the flow field solution to determine the oscillator response frequency is also described. Numerically results of oscillator frequency will be compared with the available experimental data.

Effects of Gas Flow Rate and Catalyst Loading on Polymer Electrolyte Membrane (PEM) Fuel Cell Performance and Degradation

2010 ◽  
Author(s):  
A. Chukwujekwu Okafor ◽  
Hector-Martins Mogbo
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Gas Flow ◽  
Open Circuit Voltage ◽  
Polymer Electrolyte Membrane ◽  
Open Circuit ◽  
Catalyst Loading ◽  
Gas Flow Rate ◽  
Flow Rates ◽  
Electrolyte Membrane

In this paper, the effects of gas flow rates, and catalyst loading on polymer electrolyte membrane fuel cell (PEMFC) performance was investigated using a 50cm2 active area fuel cell fixture with serpentine flow field channels machined into poco graphite blocks. Membrane Electrode Assemblies (MEAs) with catalyst and gas flow rates at two levels each (0.5mg/cm2, 1mg/cm2; 0.3L/min, 0.5L/min respectively) were tested at 60°C without humidification. The cell performance was analyzed by taking AC Impedance, TAFEL plot, open circuit voltage, and area specific resistance measurements. It was observed that MEAs with lower gas flow rate had lesser cell resistance compared to MEAs with a higher gas flow rate. TAFEL plot shows the highest exchange current density value of −2.05 mAcm2 for MEA with 0.5mg/cm2 catalyst loading operated at reactant gas flow rate of 0.3L/min signifying it had the least activation loss and fastest reaction rate. Open circuit voltage curve shows a higher output voltage and lesser voltage decay rate for MEAs tested at higher gas flow rates.

Investigation of the Effects of Catalyst Loading and Gas Flow Rate on Polymer Electrolyte Membrane (PEM) Fuel Cell Performance and Degradation

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Anthony C. Okafor ◽  
Hector-Martins C. Mogbo
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Gas Flow ◽  
Open Circuit Voltage ◽  
Polymer Electrolyte Membrane ◽  
Open Circuit ◽  
Catalyst Loading ◽  
Gas Flow Rate ◽  
Flow Rates ◽  
Electrolyte Membrane

In this paper, the effects of gas flow rates and catalyst loading on polymer electrolyte membrane fuel cell (PEMFC) performance was investigated using a 50 cm2active area fuel cell fixture with serpentine flow field channels machined into poco graphite blocks. Membrane electrode assemblies (MEAs) with catalyst and gas flow rates at two levels each (0.5 mg/cm2, 1 mg/cm2; 0.3 l/min, 0.5 l/min, respectively) were tested at 60 °C without humidification. The cell performance was analyzed by taking ac impedance, Tafel plot, open circuit voltage, and area specific resistance measurements. It was observed that MEAs with lower gas flow rate had lesser cell resistance compared to MEAs with a higher gas flow rate. Tafel plot shows the highest exchange current density value of 10−2.05 mA cm2 for MEA with 0.5 mg/cm2 catalyst loading tested at reactant gas flow rate of 0.3 l/min signifying it had the least activation loss and fastest reaction rate. Open circuit voltage-time curve shows a higher output voltage and lesser voltage decay rate for MEAs tested at higher gas flow rates.

A Novel Design of Polymer Electrolyte Membrane Fuel Cell

2007 ◽  
Author(s):  
Khaled Alhussan
Keyword(s):  
Numerical Modeling ◽  
Porous Media ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Liquid Water ◽  
Potential Field ◽  
Gas Flow ◽  
Polymer Electrolyte Membrane ◽  
Electrolyte Membrane

A fuel cell is an energy conversion device that converts the chemical energy of fuel into electrical energy. Fuel cells operate continuously if they are provided with the reactant gases, not like batteries. Fuel cells can provide power in wide range. Fuel cells are environmentally friendly; the by-product of hydrogen/oxygen fuel cell is water and heat. This paper will show a numerical modeling for this spiral design of high pressurized Polymer Electrolyte Membrane fuel cell. Numerical modeling requires understanding the physical principles of fuel cells, fluid flow, heat transfer, mass transfer in porous media, electrochemical reactions, multiphase flow with phase change, transport of current and potential field in porous media and solid conducting regions, and water transport across the polymer membrane; and this will result in optimal design process. This paper will show fuel cell models that are used in this analysis. Such as; electrochemical model: predicts local current density, voltage distributions. Potential field model: predicts current and voltage in porous and solid conducting regions. Multiphase mixture model: predicts liquid water and gas flow in the porous diffusion layers. Thin film multiphase model: tracks liquid water flow in gas flow passages. The numerical results of the theoretical modeling are shown in this paper. This paper shows the contour plots of mole fraction of H2O, H2, and O2. Results in this research include the species concentration of H2O, H2, and O2. This research also shows the plot of mass concentration of H2O, H2 and O2.

The Performance of Large-Scale PEM Fuel Cell With Interdigitated Flow Channels

2006 ◽  
Author(s):  
H. R. Shiu ◽  
C. T. Chang ◽  
Y. Y. Yan ◽  
Falin Chen
Keyword(s):  
Fuel Cell ◽  
Flow Field ◽  
Large Scale ◽  
Gas Flow ◽  
Polymer Electrolyte Membrane ◽  
Pem Fuel Cell ◽  
Flow Channel ◽  
Operating Conditions ◽  
Electrolyte Membrane ◽  
Interdigitated Flow Field

A large-scale polymer electrolyte membrane fuel cell (PEMFC) with novel interdigitated (or discontinuous) flow channel has been investigated experimentally. Interdigitated channel geometry has the advantages of effective water removal and higher reaction efficiency through forcing gas transport in the diffusion layer. In this study, multiple-Z type flow pattern has been adopted on the interdigitated channels. The active area of flow channel plate is 256 cm2 (16 cm × 16 cm). The channel width and depth are 1 mm and 0.8 mm respectively. The rib width is 1 mm. The performance of single PEM fuel cell with an interdigitated flow field is studied with appropriated operating conditions. The results demonstrated that the multiple-Z interdigitated flow channel has better performance compared with the conventional Z type by presented in the form of Current-Voltage (I-V) polarization curves. The pressure drop loss of multiple-Z interdigitated flow field increases about one time with the conventional one. The experimental results under the effects of gas humidification temperature and reactant gas flow rate, etc. have been comprehensively discussed in this work.

Heat and Mass Transport Analysis of Polymer Electrolyte Membrane Fuel Cell With Bipolar Plates

2009 ◽  
Author(s):  
Pavan Kumar Konnepati ◽  
Pradip Majumdar
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Current Density ◽  
Gas Flow ◽  
Polymer Electrolyte Membrane ◽  
Pem Fuel Cell ◽  
Bipolar Plate ◽  
Gas Diffusion ◽  
Limiting Current ◽  
Electrolyte Membrane

Fuel cells convert chemical energy of fuels into electricity directly. Their higher efficiency and low emissions made them prime candidates for next generation power requirements. The Polymer Electrolyte Membrane (PEM) fuel cell has gained attention of both transportation and stationary power generation industries. In this study a three-dimensional computational model for the simulation of Polymer Electrolyte Membrane (PEM) fuel cell unit cell is developed to understand the complex internal mechanisms, and evaluate the effects of bipolar plate designs on the cell performance. The model includes combined heat and mass transfer processes due to convection and diffusion in the gas flow channels of bi-polar plates as well in the gas diffusion layers of the electrodes, and associated electrochemical reactions in a tri-layer PEM fuel cell. Simulation is carried out with straight parallel channels for operating current density in the range from 0.5–1.5 A/cm2 showed significant insight details of PEM fuel cell in terms of distribution of reactant gases, and heat and water transport across the cell. A significantly high variation in gas concentration across the electrode–membrane interfaces and along the channel length is noticed, requiring higher stoichiometric ratios to increase the limiting current density.

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