Effects of Contact Angle Variation of the Gas Flow Channel Walls on Liquid Water Removal in PEMFC

2015 ◽  
Keyword(s):  
Contact Angle ◽  
Liquid Water ◽  
Gas Flow ◽  
Flow Channel ◽  
Water Removal ◽  
Angle Variation

Experimental Studies of Liquid Water Droplet Growth and Instability at the Gas Diffusion Layer/Gas Flow Channel Interface

2005 ◽  
Author(s):  
Michael A. Hickner ◽  
Ken S. Chen
Keyword(s):  
Contact Angle ◽  
Diffusion Layer ◽  
Liquid Water ◽  
Water Droplet ◽  
Gas Flow ◽  
Contact Angle Hysteresis ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Flow Channel ◽  
Water Droplets

Experimental investigations were carried out to visualize the dynamic behavior (contact angle hysteresis and droplet shape) of liquid water droplets on carbon paper gas diffusion layers that are typically employed in proton exchange membrane fuel cells (PEMFCs). The experimental technique mimicks the generation of liquid water and formation of droplets in an air shear flow at the gas diffusion layer – gas flow channel interface of a simulated PEMFC cathode. Images obtained of growing liquid water droplets yield information on the contact angle hysteresis and droplet height, which were subsequently used to map droplet “instability” diagrams. These instability diagrams provide quantitative guidance on liquid water droplet removal at the gas diffusion layer/gas flow channel interface under the conditions of interest. The experimentally mapped droplet diagrams are compared with those predicted using a simplified model based on a macroscopic force balance and reasonably good agreement is obtained.

Experimental Investigation of the Water Impact on Performance of Proton Exchange Membrane Fuel Cells (PEMFC) With Porous and Non-Porous Flow Channels

2012 ◽  
Author(s):  
P. Karthikeyan ◽  
H. Calvin Li ◽  
G. Lipscomb ◽  
S. Neelakrishnan ◽  
J. G. Abby ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Liquid Water ◽  
Proton Exchange Membrane ◽  
Removal Rate ◽  
Gas Diffusion ◽  
Flow Channel ◽  
Proton Exchange ◽  
Water Removal ◽  
Flow Channels ◽  
Exchange Membrane

The most critical aspect of fuel cell water management is the delicate balance of membrane hydration and avoiding cathode flooding. Liquid water accumulation in the interfacial contact area between the flow channel landing and gas diffusion layer (GDL) can dramatically impact steady and transient performance of proton exchange membrane fuel cells (PEMFCs). In this concern, a porous landing could facilitate water removal in the cathode flow channel and significantly improve PEMFCs performance. In this work, an attempt has been made to fabricate the porous interdigitated cathode flow channels from a porous carbon sheet. Performance measurements have been made with nominally identical PEMFCs using non-porous (serpentine and interdigitated) and porous (interdigitated) cathode flow channels. PEMFCs with porous interdigitated flow channels had 48% greater power output than PEMFCs with non-porous interdigitated flow channels at high current densities. For the non-porous interdigitated flow channel, significant performance loss appears to arise from greatly reduced oxygen transport rates when the water generation rate exceeds the water removal rate, however for the porous interdigitated flow channel, the design removes the accumulated liquid water from the landing area through the capillarity of its porous structure and eliminates the stagnant regions under the landing, thereby reducing liquid flooding in the interface between landing and GDL area.

Macroscopic Modeling of Two-Phase Flow Transport Inside Polymer Electrolyte Fuel Cells

2010 ◽  
Author(s):  
Masakazu Yoneda ◽  
Masato Takimoto
Keyword(s):  
Polymer Electrolyte ◽  
Liquid Water ◽  
Velocity Ratio ◽  
Gas Diffusion ◽  
Flow Channel ◽  
Polymer Electrolyte Fuel Cell ◽  
Limiting Current ◽  
Electrochemical Kinetics ◽  
Water Removal ◽  
Two Phase

It is very important to understand the transport phenomena under various operating and structural conditions to achieve the high performance of Polymer Electrolyte Fuel Cell (PEFC). In this study, the effect of liquid water removal inside flow channel on the performance of a large-sized cell was investigated. To calculate the performance of a cell or stack, we developed a simulation tool with macroscopic models of MEA characteristics such as electrochemical kinetics, catalyst utilization, limiting current density, and two-phase transport inside the gas diffusion layer (GDL) and the flow channel. At first, we investigated the effect of wall contact angle and cross-section of flow channel on the liquid water removal by the Moving Particle Semi-implicit method and calculated the velocity ratio (liquid water velocity for gas velocity) inside the flow channel including the effect of mesoscopic structure of GDL. Applying this correlation to the two-phase model of the macroscopic PEFC simulation, we confirmed that the performance in the case of hydrophilic and shallow-shaped channel is much better in other case under low utilization operation.

Study of Water Droplet Removal on Etched-Metal Surfaces for Proton Exchange Membrane Fuel Cell Flow Channel

2016 ◽  
Vol 13 (1) ◽  
Author(s):  
S. Shimpalee ◽  
V. Lilavivat
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Stainless Steel ◽  
Fuel Cell ◽  
Liquid Water ◽  
Water Droplet ◽  
Proton Exchange Membrane ◽  
Flow Channel ◽  
Proton Exchange ◽  
Exchange Membrane

Within a proton exchange membrane fuel cell (PEMFC), the transport route of liquid water begins at the cathode catalyst layer, and then progresses into the gas diffusion layer (GDL) where it then goes into the flow channel. At times, significant accumulation of liquid droplets can be seen on either side of the membrane on the surface of the flow channel. In this work, liquid water and the flow dynamics within the transport channel were examined experimentally, with the channel acting as an optical window. Ex situ interpretations of the liquid water and flow patterns inside the channel were established. Liquid water droplet movements were analyzed by considering the change of the contact angle with different flow rates. Also, various surface roughness of stainless steel was used to determine the relationships between flow rate and the contact angles. When liquid water is found within the gas channels of PEMFCs, the channels' characteristic changes become more dominant and it becomes more of a necessity to monitor the effects. Physical motion of water droplets in the flow channels of PEMFCs is important. The surface roughness properties were used to describe the contact angle and the droplet removal force on the stainless steel flow channel.

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