scholarly journals Evaporative Liquid Water Removal from Diffusion Media of PEFC

2009 ◽  
Keyword(s):  
Liquid Water ◽  
Water Removal ◽  
Diffusion Media

Predicting Liquid Water Saturation Through Differently Structured Cathode Gas Diffusion Media of a Proton Exchange Membrane Fuel Cell

2012 ◽  
Vol 9 (2) ◽  
Author(s):  
N. Akhtar ◽  
P. J. A. M. Kerkhof
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Proton Exchange Membrane ◽  
Water Saturation ◽  
Catalyst Layer ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Diffusion Media ◽  
Exchange Membrane

The role of gas diffusion media with differently structured properties have been examined with emphasis on the liquid water saturation within the cathode of a proton exchange membrane fuel cell (PEMFC). The cathode electrode consists of a gas diffusion layer (GDL), a micro-porous layer and a catalyst layer (CL). The liquid water saturation profiles have been calculated for varying structural and physical properties, i.e., porosity, permeability, thickness and contact angle for each of these layers. It has been observed that each layer has its own role in determining the liquid water saturation within the CL. Among all the layers, the GDL is the most influential layer that governs the transport phenomena within the PEMFC cathode. Besides, the thickness of the CL also affects the liquid water saturation and it should be carefully controlled.

Effect of the Micro-Porous Layer-Gas Diffusion Layer Interface on Water Transport in Polymer Electrolyte Fuel Cells

2009 ◽  
Author(s):  
Joshua Preston ◽  
Richard Fu ◽  
Xiaoyu Zhang ◽  
Ugur Pasaogullari
Keyword(s):  
Polymer Electrolyte ◽  
Cross Section ◽  
Porous Layer ◽  
Diffusion Layer ◽  
Liquid Water ◽  
Water Saturation ◽  
Numerical Models ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Diffusion Media

An investigation of the liquid water saturation across the cross-section of an operating polymer electrolyte fuel cell is performed to analyze the saturation discontinuity predicted by numerical models. Numerical models have predicted a discontinuity in the liquid water saturation at the interface of the micro-porous layer and the coarser macroporous region of the gas diffusion layer. High-resolution through plane neutron radiography is used to acquire the water content distribution across the thickness of the gas-diffusion layer and study the effects of the interface. The measured liquid water profiles indicate no obvious discontinuity in the liquid water saturation across the cross-section of the bi-layer gas diffusion layer when large areas are averaged spatially. Evidence of the discontinuity is found when small spatial averaging is used in certain locations. Other locations show no evidence of the discontinuity. Scanning electron microscopy is used to examine the microstructure of two types of the bi-layer diffusion media. The images show that the approximation of the interface as a sudden, distinct feature may not be appropriate. The results suggest that a model that considers the existence of an interfacial region in the diffusion media may be appropriate, in which the properties vary continuously.

Effect of Operating Temperature on the Water Removal in a Polymer Electrolyte Fuel Cell

2008 ◽  
Author(s):  
Wanyuan Shi ◽  
Nobuyuki Oshima ◽  
L. Kumar Saha ◽  
Eru Kurihara
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Liquid Water ◽  
Water Saturation ◽  
Operating Temperature ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cell ◽  
Water Removal ◽  
Operation Temperature ◽  
Increasing Temperature

In order to investigate the effect of operation temperature on the liquid water removal in the polymer electrolyte fuel cell, a one-dimensional steady state mathematical model was developed for the cathode gas diffusion layer (GDL). Numerical results indicate that liquid water saturation significantly increases with increases in the operating temperature of the fuel cell because the capillary pressure in the hydrophobic GDL decreases with increasing temperature. An elevated operating temperature has an undesirable influence on the removal of liquid water inside the GDL. A reported peculiar phenomenon in which the flooding of the fuel cell under a high operating temperature and an over-saturated environment is more serious in a GDL combined with a micro-porous layer (MPL) than in a GDL without an MPL (Lim and Wang, Electrochimica Acta, 49, pp. 4149–4156, 2004) is explained based on the present analysis.

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.

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