Effects of operating parameters on transport phenomena and cell performance of PEM fuel cells with conventional and contracted flow field designs

In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

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Effect of Vibration on the Liquid Water Transport of PEM Fuel Cells

Volume 6: Emerging Technologies: Alternative Energy Systems; Energy Systems: Analysis, Thermodynamics and Sustainability ◽

10.1115/imece2009-12062 ◽

2009 ◽

Author(s):

Luis Breziner ◽

Peter Strahs ◽

Parsaoran Hutapea

Keyword(s):

Fuel Cells ◽

Fuel Cell ◽

Water Transport ◽

Liquid Water ◽

Pem Fuel Cells ◽

Gas Diffusion ◽

Cell Performance ◽

Sinusoidal Vibration ◽

Fuel Cell Performance ◽

Liquid Water Transport

The objective of this research is to analyze the effects of vibration on the performance of hydrogen PEM fuel cells. It has been reported that if the liquid water transport across the gas diffusion layer (GDL) changes, so does the overall cell performance. Since many fuel cells operate under a vibrating environment –as in the case of automotive applications, this may influence the liquid water concentration across the GDL at different current densities, affecting the overall fuel cell performance. The problem was developed in two main steps. First, the basis for an analytical model was established using current models for water transport in porous media. Then, a series of experiments were carried, monitoring the performance of the fuel cell for different parameters of oscillation. For sinusoidal vibration at 10, 20 and 50Hz (2 g of magnitude), a decrease in the fuel cell performance by 2.2%, 1.1% and 1.3% was recorded when compared to operation at no vibration respectively. For 5 g of magnitude, the fuel cell reported a drop of 5.8% at 50 Hz, whereas at 20 Hz the performance increased by 1.3%. Although more extensive experimentation is needed to identify a relationship between magnitude and frequency of vibration affecting the performance of the fuel cell as well as a throughout examination of the liquid water formation in the cathode, this study shows that sinusoidal vibration, overall, affects the performance of PEM fuel cells.

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Innovative Flow-Field Combination Design on Direct Methanol Fuel Cell Performance

Journal of Fuel Cell Science and Technology ◽

10.1115/1.2744056 ◽

2006 ◽

Vol 4 (3) ◽

pp. 365-368 ◽

Cited By ~ 8

Author(s):

Guo-Bin Jung ◽

Ay Su ◽

Cheng-Hsin Tu ◽

Fang-Bor Weng ◽

Shih-Hung Chan

Keyword(s):

Fuel Cells ◽

Flow Field ◽

Direct Methanol Fuel Cells ◽

Flow Fields ◽

Cell Performance ◽

Fuel Cell Performance ◽

Serpentine Flow Field ◽

Structure Of Flow ◽

Direct Methanol ◽

Stable Performance

The flow-field design of direct methanol fuel cells (DMFCs) is an important subject about DMFC performance. Flow fields play an important role in the ability to transport fuel and drive out the products (H2O,CO2). In general, most fuel cells utilize the same structure of flow field for both anode and cathode. The popular flow fields used for DMFCs are parallel and grid designs. Nevertheless, the characteristics of reactants and products are entirely different in anode and cathode of DMFCs. Therefore, the influences of flow fields design on cell performance were investigated based on the same logic with respect to the catalyst used for cathode and anode nonsymmetrically. To get a better and more stable performance of DMFCs, three flow fields (parallel, grid, and serpentine) utilized with different combinations were studied in this research. As a consequence, by using parallel flow field in the anode side and serpentine flow-field in the cathode, the highest power output was obtained.

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Flow-Field Designs of Bipolar Plates in PEM Fuel Cells: Theory and Applications

Fuel Cells ◽

10.1002/fuce.201200074 ◽

2012 ◽

Vol 12 (6) ◽

pp. 989-1003 ◽

Cited By ~ 49

Author(s):

J. Wang ◽

H. Wang

Keyword(s):

Fuel Cells ◽

Flow Field ◽

Pem Fuel Cells ◽

Bipolar Plates

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