Two-phase flow model of the cathode of PEM fuel cells using interdigitated flow fields

AIChE Journal ◽  
2000 ◽  
Vol 46 (10) ◽  
pp. 2053-2064 ◽  
Author(s):  
Wensheng He ◽  
Jung S. Yi ◽  
Trung Van Nguyen
Keyword(s):  
Fuel Cells ◽  
Flow Model ◽  
Two Phase Flow ◽  
Flow Fields ◽  
Pem Fuel Cells ◽  
Phase Flow ◽  
Two Phase

The Role of Channel Plurality in Two-Phase Flow Instabilities in PEM Cathode Channels

2011 ◽  
Author(s):  
Nicholas Siefert ◽  
Colin O’Shea ◽  
Shawn Litster
Keyword(s):  
Fuel Cells ◽  
Two Phase Flow ◽  
Pem Fuel Cells ◽  
Flow Instabilities ◽  
Active Area ◽  
Phase Flow ◽  
Constant Number ◽  
Two Phase ◽  
Voltage Loss ◽  
Dimensional Parameters

Water management is a critical issue in the development of proton exchange membrane (PEM) fuel cells with robust operation. Liquid water can accumulate and flood the gas delivery microchannels and the porous electrodes within PEM fuel cells and deteriorate performance. Since the liquid distribution fluctuates in time for two-phase flow, the rate of oxygen transport to the cathode catalyst layer also fluctuates, resulting in unstable power density and efficiency. In previous research into measuring the voltage loss and voltage fluctuation due to two-phase flow instabilities in the cathode channels of PEM fuel cells, we investigated the effect of the number of parallel channels covering the active area by studying flow fields with varying numbers of parallel channels (4 to 25) while keeping the active area constant at 5 cm2. The resulting voltage loss and fluctuation measurements were expressed as functions of two non-dimensional parameters: channel plurality and the air flow stoichiometric ratio. Channel plurality is a flow field design parameter that defines the number of channels per unit of active area, which is non-dimensionalized by the cross-sectional area of the channels. In this paper, we expand upon our prior studies by studying cathode flow field designs of varying active area, from 5 cm2 to 25 cm2, with a constant number of 25 channels. By increasing the active area with a constant number of channels, we are reducing the channel plurality value. The new results are mapped back to the non-dimensional parameters to extract empirical scaling rules for voltage loss and fluctuation. Furthermore, we compare this data to our prior work with constant active area and identify the significance of the fuel cell size in the scaling relationships. Finally, a refined scaling is presented for generalizing the results for fuel cells having different active area and number of channels.

Two-Dimensional Simulations of Gas-Liquid Two-Phase Flow in Mini channels of PEM Fuel Cell Flow Field

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Wei Du ◽  
Lifeng Zhang ◽  
Xiaotao T Bi ◽  
David Wilkinson ◽  
Jürgen Stumper ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Strong Dependence ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Contact Angles ◽  
Phase Flow ◽  
Two Phase ◽  
Mini Channels

Effective water management is one of the key strategies for improving the performance and durability of PEM fuel cells. Phenomena such as membrane dehydration, catalyst layer flooding and two-phase flow in flow-channels are all determined by the distribution and movement of water during cell operation. In this study, gas-liquid flow in mini-channels relevant to fuel cells was numerically studied using a CFD two-phase flow model in combination with a volume of fluid (VOF) method. The results show that the surface wettability of the channel wall can greatly affect the flow pattern, especially when the channel walls and the gas diffusion layer (GDL) surface possess different contact angles. When the channel walls are more hydrophobic, more water is accumulated on the GDL. An increase in the surface tension results in a slight increase of slug frequency and a slight decrease in slug length. The onset of slugging along the channel is determined by the gas-liquid mixture velocity, gas-to-liquid flow ratio and the way water is introduced into the gas flow channel. Furthermore, the calculated pressure drop fluctuations show a strong dependence on the channel liquid content and the slug length.

Numerical study of two-phase flow patterns in the gas channel of PEM fuel cells with tapered flow field design

2014 ◽  
Vol 39 (5) ◽  
pp. 2261-2273 ◽  
Author(s):  
Erasmo Mancusi ◽  
Éliton Fontana ◽  
Antônio Augusto Ulson de Souza ◽  
Selene M.A. Guelli Ulson de Souza
Keyword(s):  
Fuel Cells ◽  
Flow Field ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Pem Fuel Cells ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Gas Channel ◽  
Flow Field Design
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