Gas flow rate distributions in parallel minichannels for polymer electrolyte membrane fuel cells: Experiments and theoretical analysis

2010 ◽  
Vol 195 (10) ◽  
pp. 3231-3239 ◽  
Author(s):  
Lifeng Zhang ◽  
Hsiaotao T. Bi ◽  
David P. Wilkinson ◽  
Jürgen Stumper ◽  
Haijiang Wang
Author(s):  
A. Chukwujekwu Okafor ◽  
Hector-Martins Mogbo

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.


Author(s):  
Anthony C. Okafor ◽  
Hector-Martins C. Mogbo

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.


Author(s):  
Khaled Alhussan

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.


Author(s):  
Xiongbiao Wan ◽  
Zhigang Zhan ◽  
panxing Jiang ◽  
Yuan Yu ◽  
Chenglong Wang ◽  
...  

Abstract The efficient, fast, and reliable cold start of polymer electrolyte membrane fuel cells is one of the major challenges for their commercialization. In this paper a segmented single cell is used to simulate the end plate effects of the stack and to investigate how the effects work. The results demonstrate that the end cells in the stack have the lowest performance, the reasons for which include the lowest temperature of the cells themselves, and probably also ice blocking in part an area inside the MEA, or in the channels, or in both together. In order to mitigate or even eliminate the influence of ice formation in the end cells, the temperature of the end plates should be increased to -10℃ or above when liquid water is generated. A high inlet gas flow rate facilitates the discharge of supercooled water and is conducive to successful cold start.


2010 ◽  
Vol 195 (15) ◽  
pp. 4622-4627 ◽  
Author(s):  
Tommy T.H. Cheng ◽  
Nengyou Jia ◽  
Vesna Colbow ◽  
Silvia Wessel ◽  
Monica Dutta

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