Operating Condition Optimization of PEMFC via Visualization Technique

2013 ◽  
Vol 393 ◽  
pp. 787-792 ◽  
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.

Measurement of Liquid Water Accumulation in a Proton Exchange Membrane Fuel Cell With Dead-Ended Anode

2008 ◽  
Author(s):  
Jason B. Siegel ◽  
Denise A. McKay ◽  
Anna G. Stefanopoulou
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Voltage Drop ◽  
Cell Voltage ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Neutron Imaging ◽  
Water Dynamics ◽  
Water Flooding ◽  
Carbon Cloth

The operation and accumulation of liquid water within the cell structure of a polymer electrolyte membrane fuel cell (PEMFC) with a dead-ended anode is observed using neutron imaging. The measurements are performed on a single cell with 53 square centimeter active area, Nafion 111-IP membrane and carbon cloth Gas Diffusion Layer (GDL). Even though dry hydrogen is supplied to the anode via pressure regulation, accumulation of liquid water in the anode gas distribution channels was observed for all current densities up to 566 mA cm−2 and 100% cathode humidification. The accumulation of liquid water in the anode channels is followed by a significant voltage drop even if there is no buildup of water in the cathode channels. Anode purges and cathode surges are also used as a diagnostic tool for differentiating between anode and cathode water flooding. The rate of accumulation of anode liquid water, and its impact on the rate of cell voltage drop is shown for a range of temperature, current density, cathode relative humidity and air stoichiometric conditions. Neutron imaging of the water while operating the fuel cell under dead-ended anode conditions offers the opportunity to observe water dynamics and measured cell voltage during large and repreatable transients.

Analysis of Pressure Drop and Water Flooding of Two-Phase Flow Along Channels for a PEM Fuel Cell System

2009 ◽  
Author(s):  
Jinglin He ◽  
Song-Yul Choe ◽  
Chang-Ouk Hong
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Relative Humidity ◽  
Liquid Water ◽  
Water Distribution ◽  
Gas Flow ◽  
Pem Fuel Cell ◽  
Cell System ◽  
Water Flooding ◽  
Two Phase

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.

The Effects of Feeding Configurations to Water Flooding and General Performance of a Proton Exchange Membrane Fuel Cell

2005 ◽  
Author(s):  
A. B. Mahmud Hasan ◽  
S. M. Guo ◽  
S. V. Ekkad
Keyword(s):  
Fuel Cell ◽  
Power Density ◽  
Current Density ◽  
Proton Exchange Membrane ◽  
Cell Voltage ◽  
Bipolar Plate ◽  
Proton Exchange ◽  
Water Flooding ◽  
Cathode Side ◽  
Exchange Membrane

The performance of a Proton Exchange Membrane Fuel Cell (PEMFC) using different feeding configurations has been studied. Three bipolar plates, namely serpentine, straight channel and interdigitated designs, were arranged in different combinations for the PEMFC anode and cathode sides. Nine combinations in total were tested under different flow rates, working temperatures and loadings. The cell voltage versus current density and the cell power density versus current density curves were obtained. After operating the PEMFC under high current densities, the cell was split and the water flooding in the feeding channels was visually inspected. Experimental results showed that for different feeding configurations, interdigitated bipolar plate in anode side and serpentine bipolar plate in cathode side had the best performance in terms of cell voltage-current density curve, power density output rate, percentage of flooded area in the feeding channels, the pattern of flooding and the fuel utilization rate.

Liquid water flooding in a proton exchange membrane fuel cell cathode with an interdigitated design

2011 ◽  
Vol 35 (15) ◽  
pp. 1292-1311 ◽  
Author(s):  
Simo Kang ◽  
Biao Zhou ◽  
Chin-Hsiang Cheng ◽  
Huan-Ruei Shiu ◽  
Chun-I Lee
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Water Flooding ◽  
Fuel Cell Cathode ◽  
Exchange Membrane ◽  
Cell Cathode

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

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.

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

2010 ◽  
Vol 7 (6) ◽  
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.

Neutron Imaging of Water Accumulation in the Active Area and Channel-to-Manifold Transitions of a PEMFC

2013 ◽  
Author(s):  
Xuan Liu ◽  
Thomas A. Trabold ◽  
Jeffrey J. Gagliardo ◽  
David L. Jacobson ◽  
Daniel S. Hussey
Keyword(s):  
Fuel Cell ◽  
Current Density ◽  
Liquid Water ◽  
Driving Force ◽  
Cell Voltage ◽  
Neutron Imaging ◽  
Active Area ◽  
Water Volume ◽  
Imaging Method ◽  
Water Accumulation

Management of liquid water formed by the electrochemical fuel cell reaction is a key factor in PEMFC performance and durability. For practical stack applications, an important consideration is the transport of liquid water at the transition between the ends of the bipolar plate channels and the manifolds, where excess reactant flows from all the individual cells are combined and directed to the stack exhaust. In this region, gas-phase momentum can be very low, especially on the anode, where there is little driving force to remove liquid water that may accumulate as a result of geometrical or surface energy variations, or due to relatively low temperatures that exist outside of the fuel cell active area. This study seeks to characterize the water accumulated within the active area and at the channel-to-manifold transition regions at both the anode and cathode outlets, as a function of cell operating temperature and current density. The neutron imaging method was applied to directly measure the water volumes within the transition regions, and provide a comparison to simultaneously measured water volume within the cell active area. Transition-region water was found to be weakly dependent on current density, suggesting that once water forms in this area, little driving force exists to extract it entirely by means of gas momentum. Moreover, it was found that the active area water volume is strongly dependent on cell temperature, and temperature variation of as little as 0.5 °C can produce a significant change in water accumulation which is reflected in the cell voltage.

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

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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