scholarly journals Pore-Scale Investigation of Coupled Two-Phase and Reactive Transport in the Cathode Electrode of Proton Exchange Membrane Fuel Cells

2022 ◽  
Author(s):  
Shengjie Ye ◽  
Yuze Hou ◽  
Xing Li ◽  
Kui Jiao ◽  
Qing Du
Keyword(s):  
Fuel Cells ◽  
Liquid Water ◽  
Reactive Transport ◽  
Proton Exchange Membrane ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Two Phase ◽  
Cathode Electrode ◽  
And Performance ◽  
Exchange Membrane

AbstractA three-dimensional multicomponent multiphase lattice Boltzmann model (LBM) is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells. The gas diffusion layer (GDL) and microporous layer (MPL) are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved, and the catalyst layer is simplified as a superthin layer to address the electrochemical reaction, which provides a clear description of the flooding effect on mass transport and performance. Different kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and performance under the flooding condition. The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under flooding. The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores. Moreover, the MPL helps in the uniform distribution of oxygen for an efficient in-plane transport capacity. Crack and perforation structures can accelerate the water transport in the assembly. The systematic perforation design yields the best performance under flooding by separating the transport of liquid water and oxygen.

Design Concepts for Directed Exit Flow in Micro Fuel Cells

2004 ◽  
Author(s):  
Wei Shi ◽  
Sang-Joon Lee
Keyword(s):  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Design Concepts ◽  
New Concepts ◽  
And Performance ◽  
Electronic Load ◽  
Exchange Membrane

Miniature and micro fuel cells continue to advance as promising alternatives for efficient and portable electric power. This paper presents a study of experimental modifications to the exit flow configuration of microchannels used in small proton-exchange-membrane fuel cells. New concepts for exit geometry are presented, which promote effective water removal and provide reactant back-pressure in an efficient and self-contained manner. Cell assembly is designed such that reactants must necessarily flow laterally through the gas diffusion electrodes near the exit, rather than simply pass over the free backside surfaces of these electrodes. Multiple prototypes were produced using microfabrication techniques with channel sizes of 100 and 200 microns, and performance was tested using a hydrogen-air test station with programmable electronic load. One of the new concepts in particular showed a marked improvement from 28 mW/cm2 peak power density under baseline conditions to 37 mW/cm2 for the modified design under similar operating conditions. The design offers an opportunity for higher performance in miniature fuel cells with low gas consumption and no additional cost.

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.

scholarly journals Pore-Scale Modeling of Air–Water Two Phase Flow and Oxygen Transport in Gas Diffusion Layer of Proton Exchange Membrane Fuel Cell

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3812
Author(s):  
Chongbo Zhou ◽  
Lingyi Guo ◽  
Li Chen ◽  
Xin Tian ◽  
Tiefeng He ◽  
...  
Keyword(s):  
Liquid Water ◽  
Reactive Transport ◽  
Proton Exchange Membrane ◽  
Water Saturation ◽  
Gas Diffusion ◽  
Transport Processes ◽  
Proton Exchange ◽  
Scale Model ◽  
Pore Scale ◽  
Two Phase

Understanding multiphase flow and gas transport occurring in electrodes is crucial for improving the performance of proton exchange membrane fuel cells. In the present study, a pore-scale model using the lattice Boltzmann method (LBM) was proposed to study the coupled processes of air–water two-phase flow and oxygen reactive transport processes in porous structures of the gas diffusion layer (GDL) and in fractures of the microscopic porous layer (MPL). Three-dimensional pore-scale numerical results show that the liquid water generation rate is gradually reduced as the oxygen consumption reaction proceeds, and the liquid water saturation in the GDL increases, thus the constant velocity inlet or pressure inlet condition cannot be maintained while the results showed that at t = 1,200,000 iterations after 2900 h running time, the local saturation at the GDL/MPL was about 0.7, and the maximum value was about 0.83, while the total saturation was 0.35. The current density reduced from 2.39 to 0.46 A cm-2. Effects of fracture number were also investigated, and the results showed that for the fracture numbers of 8, 12, 16, and 24, the breakthrough point number was 4, 3, 3, and 2, respectively. As the fracture number increased, the number of the water breakthrough points at the GDL/GC interface decreased, the liquid water saturation inside the GDL increased, the GDL/MPL interface was more seriously covered, and the current density decreased. The pore-scale model for the coupled multiphase reactive transport processes is helpful for understanding the mechanisms inside the porous electrodes of PEMFC.

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