Three-dimensional effects of liquid water flooding in the cathode of a PEM fuel cell

The flow in gas flow channels of an operating polymer electrolyte membrane (PEM) fuel cell has a two-phase characteristic that includes air, water vapor and liquid water and significantly affects the water flooding, pressure distribution along the channels, and subsequently the performance of the cell and system. Presence of liquid water in channels prevents transport of the reactants to the catalysts and increases the pressure difference between the inlet and outlet of channels, which leads to high parasitic power of pumps used in air and fuel supply systems. We propose a model that enables prediction of pressure drop and liquid water distribution along channels and analysis of water flooding in an operating fuel cell. The model was developed based on a gas-liquid two-phase separated flow that considers the variations of gas pressure, mass flow rate, relative humidity, viscosity, void fraction, and density along the channels on both sides. Effects of operating parameters that include stoichoimetric ratio, relative humidity, and inlet pressure on the pressure drop and water flooding along the channels were analyzed.

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Effect of Hydrophobicity in Cathode Porous Media on PEM Fuel Cell Performance

ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer, Volume 2 ◽

10.1115/mnhmt2009-18438 ◽

2009 ◽

Author(s):

Lijun Yang ◽

Wenan Li ◽

Xiaoze Du ◽

Yongping Yang

Keyword(s):

Fuel Cell ◽

Flow Field ◽

Water Content ◽

Liquid Water ◽

Pem Fuel Cell ◽

Liquid Water Content ◽

Contact Angles ◽

Water Flooding ◽

Water Transportation ◽

Overall Performance

The water management is a key issue for the performance of a polymer electrolyte membrane (PEM) fuel cell. Materials of the fuel cell would affect the water transportation in the flow field thus influence the overall performance of a fuel cell. Three dimensional single-channel, counter-flow model was built to analyze the performance of PEM fuel cell. Different surface contact angles were set to the liquid water droplets in the catalyst layers (CL) and gas diffusion layers (GDL) to present the different wetting property characterizations of the materials. Assuming that the contact angles range from 75° to 150°, the liquid water content and distribution in the cathode GDL were investigated in details. Numerical analysis showed that the hydrophobicity of the structure affects water transportation in the fuel cell significantly. Hydrophobic materials could lower the rate of water saturation in the flow field thus prevent the water flooding in the cathode side. When the surface contact angel of cathode CL and GDL was set to 135°, the liquid water content is least in the GDL. I-V polarization curves of the fuel cell with different materials were also developed to analyze the overall performance. As a result, proper hydrophobic material would lower the rate of cathode water flooding in PEM and benefit the performance of PEM fuel cell.

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Effect of Hydrophobicity in Cathode Porous Media on PEM Fuel Cell Performance

Journal of Fuel Cell Science and Technology ◽

10.1115/1.4001051 ◽

2010 ◽

Vol 7 (6) ◽

Cited By ~ 2

Author(s):

Lijun Yang ◽

Wenan Li ◽

Xiaoze Du ◽

Yongping Yang

Keyword(s):

Fuel Cell ◽

Flow Field ◽

Water Content ◽

Liquid Water ◽

Pem Fuel Cell ◽

Liquid Water Content ◽

Contact Angles ◽

Water Flooding ◽

Water Transportation ◽

Overall Performance

Water management is a key issue for the performance of a polymer electrolyte membrane (PEM) fuel cell. Materials of the fuel cell would affect the water transportation in the flow field, thus influence, the overall performance of the fuel cell. A three dimensional, single-channel, counterflow model was built to analyze the performance of the PEM fuel cell. Different surface contact angles were set to the liquid water droplets in the catalyst layers (CLs) and gas diffusion layers (GDLs) to present the different wetting property characterizations of the materials. Assuming that the contact angle ranges from 75 deg to 150 deg, the liquid water content and distribution in the cathode GDL were investigated in details. Numerical analysis showed that the hydrophobicity of the structure affects the water transportation in the fuel cell significantly. Hydrophobic materials could lower the rate of water saturation in the flow field, thus preventing the water flooding in the cathode side. When the surface contact angles of the cathode CL and GDL were set to 135 deg, the liquid water content is least in the GDL. I-V polarization curves of the fuel cell with different materials were also developed to analyze the overall performance. As a result, proper hydrophobic material would lower the rate of cathode water flooding in PEM and benefit the performance of PEM fuel cell.

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Effect of Porosity Gradient in Gas Diffusion Layer on Cell Performance With Thin-Film Agglomerate Model in Cathode Catalyst Layer of a PEM Fuel Cell

ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2011-54838 ◽

2011 ◽

Author(s):

Chun-I Lee ◽

Shiqah-Ping Jung ◽

Kan-Lin Hsueh ◽

Chi-Chang Chen ◽

Wen-Chen Chang

Keyword(s):

Thin Film ◽

Fuel Cell ◽

Diffusion Layer ◽

Liquid Water ◽

Water Saturation ◽

Catalyst Layer ◽

Gas Diffusion Layer ◽

Pem Fuel Cell ◽

Gas Diffusion ◽

Water Flooding

A one-dimensional, steady-state, two-phase, isothermal numerical simulations were performed to investigate the effect on cell performance of a PEM fuel cell under non-uniform porosity of gas diffusion layer. In the simulation, the non-uniform porosity of gas diffusion layer was taken into account to analyze the transport phenomena of water flooding and mass transport in the gas diffusion layer. The porosity of the gas diffusion layer is treated as a linear function. Furthermore, the structure of the catalyst layer is considered to be a cylindrical thin-film agglomerate. Regarding the distribution analysis of liquid water saturation, oxygen concentration and water concentration depend on the porosity of gas diffusion layer. In the simulation, the εCG and εGC represent the porosity of the interfaces between the channel and gas diffusion layer and the gas diffusion layer and the catalyst layer, respectively. The simulation results indicate that when the (εCG, εGC) = (0.8, 0.4), higher liquid water saturation appears in the gas diffusion layer and the catalyst layer. On the contrary, when the (εCG, εGC) = (0.4, 0.4), lower liquid water saturation appears. Once the liquid water produced by the electrochemical reaction and condensate of vapor water may accumulate in the open pores of the gas diffusion layer and reduced the oxygen transport to the catalyst sites. This research attempts to use a thin-film agglomerate model, which analyze the significant transport phenomena of water flooding and mass transport under linear porosity gradient of gas diffusion layer in the cathode of a PEM fuel cell.

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Three-dimensional simulation of a PEM fuel cell with experimentally measured through-plane gas effective diffusivity considering Knudsen diffusion and the liquid water effect in porous electrodes

Electrochimica Acta ◽

10.1016/j.electacta.2019.06.120 ◽

2019 ◽

Vol 318 ◽

pp. 770-782 ◽

Cited By ~ 10

Author(s):

Yulin Wang ◽

Shixue Wang ◽

Shengchun Liu ◽

Hua Li ◽

Kai Zhu

Keyword(s):

Fuel Cell ◽

Liquid Water ◽

Knudsen Diffusion ◽

Three Dimensional ◽

Effective Diffusivity ◽

Pem Fuel Cell ◽

Porous Electrodes ◽

Water Effect ◽

Dimensional Simulation

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3-D Model of Proton Exchange Membrane Fuel Cells

10.1115/imece2000-1365 ◽

2000 ◽

Author(s):

Tianhong Zhou ◽

Hongtan Liu

Keyword(s):

Fuel Cell ◽

Proton Exchange Membrane ◽

Three Dimensional ◽

Flow Characteristics ◽

Pem Fuel Cell ◽

Proton Exchange ◽

Three Dimensional Model ◽

Chemical Reaction Kinetics ◽

Fuel Cell Performance ◽

D Model

Abstract A comprehensive three-dimensional model for a proton exchanger membrane (PEM) fuel cell is developed to evaluate the effects of various design and operating parameters on fuel cell performance. The geometrical model includes two distinct flow channels separated by the membrane and electrode assembly (MEA). This model is developed by coupling the governing equations for reactant mass transport and chemical reaction kinetics. To facilitate the numerical solution, the full PEM fuel cell was divided into three coupled domains according to the flow characteristics. The 3-D model has been applied to study species transport, heat transfer, and current density distributions within a fuel cell. The predicated polarization behavior is shown to compare well with experimental data from the literature. The modeling results demonstrate good potential for this computational model to be used in operation simulation as well as design optimization.

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Operating Condition Optimization of PEMFC via Visualization Technique

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.393.787 ◽

2013 ◽

Vol 393 ◽

pp. 787-792 ◽

Cited By ~ 1

Author(s):

Khairul Imran Sainan ◽

Wan Ahmad Najmi Wan Mohamed ◽

Firdaus Mohamad ◽

Norhisyam Jenal

Keyword(s):

Fuel Cell ◽

Liquid Water ◽

Cell Voltage ◽

Water Flooding ◽

Root Cause ◽

Condition Optimization ◽

Dry Conditions ◽

Voltage Performance ◽

Stable Voltage ◽

Membrane Dehydration

Fuel cell water management has two conflicting requirements; too less water causing membrane dehydration and too much water causing liquid water flooding. Both phenomena resulting in significantly instability voltage performance because of imbalance water presence. Therefore, it is vital to analyze and understand the root cause of the problem hence a 96cm2 transparent fuel cell was analyzed experimentally. The fuel cell allows clear visualization of flow channels, thus making it practical to analyze the transportation of reactants and products behavior. The experimental analyses were conducted under different reactant flow rate and inlet humidification variations. Highest cell performance was obtained under both reactant inlets humidification with largest air flow rates. On the other hand, when fuel and air in dry conditions, relatively lower cell voltage was obtained. Meanwhile, stable voltage was obtained under anode humidified and cathode non-humidified conditions with correct air to fuel ratio. Images of liquid water and voltage behavior are presented graphically corresponding to the changes in performance.

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