The Impact of an MPL on Water Management of an Operating PEMFC Using Synchrotron X-Ray Radiography

2012 ◽  
Author(s):  
J. Lee ◽  
J. Hinebaugh ◽  
A. Bazylak
Keyword(s):  
Water Management ◽  
Current Density ◽  
Polymer Electrolyte Membrane ◽  
Gas Diffusion ◽  
Carbon Paper ◽  
Stoichiometric Ratio ◽  
Operation Performance ◽  
X Ray ◽  
Electrolyte Membrane ◽  
The Impact

High quality through-plane images of an operating polymer electrolyte membrane fuel cell (PEMFC) were visualized by employing synchrotron X-ray radiography to quantify liquid water in gas diffusion layers (GDL). Two types of GDLs, Toray carbon paper with and without micro-porous layers (MPLs), were employed and imaged during the operation. Performance data and x-ray images of these GDLs are compared to determine the impact of an MPL on water management. At low current density (<0.4A/cm2) under high stoichiometric ratio, the MPL has little overall effect, but may behave as a diffusion barrier for reactants. At higher current density (0.6A/cm2) and under low stoichiometric ratios, the MPL is observed to significantly affect the water management of the PEMFC and is credited for increased cell performance.

Synchrotron X-Ray Investigation of Membrane Water Distribution in Polymer Electrolyte Membrane Fuel Cell Applications

2017 ◽  
Author(s):  
Rupak Banerjee ◽  
Chuzhang Han ◽  
Nan Ge ◽  
Aimy Bazylak
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Diffusion Layer ◽  
Current Density ◽  
Water Distribution ◽  
Polymer Electrolyte Membrane ◽  
Gas Diffusion ◽  
Cell Performance ◽  
X Ray ◽  
Electrolyte Membrane

Water management is a critical component of extracting optimum performance and efficiency from polymer electrolyte membrane (PEM) fuel cells. During fuel cell operation, a balance needs to be maintained between excess water blocking the reactant pathways through the gas diffusion layer, and the requirement for membrane hydration. The ionic conductivity through the membrane depends strongly on the hydration of the membrane. The reactant gases in a PEM fuel cell are supplied through a humidification system to maintain appropriate levels of hydration in the membrane. The removal of the anode humidifier would significantly reduce the balance of plant costs and reduce the volume required for the fuel cell in an automotive setting. However, removing the anode humidification system could have adverse effects on membrane hydration and on fuel cell performance. In this study, the anode humidification was varied and the cell performance and the membrane resistance were monitored. Synchrotron X-ray radiography was conducted simultaneously to visualize the water distribution in the membrane, the gas diffusion layer, and the associated interfaces. It was observed that the anode humidification had a strong impact on the performance of the fuel cell, with the dry condition leading to voltage instability at a current density below 1.0 A/cm2. The membrane water content was observed to decrease with increases in operating current density.

Effect of Channel Geometry on Two-Phase Flow Structure in Fuel Cell Gas Channels

2011 ◽  
Author(s):  
Cody D. Rath ◽  
Satish G. Kandlikar
Keyword(s):  
Water Management ◽  
Fuel Cell ◽  
High Efficiency ◽  
Polymer Electrolyte Membrane ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Ex Situ ◽  
Two Phase ◽  
Electrolyte Membrane ◽  
Excess Water

Water management issues continue to be a major concern for the performance of polymer electrolyte membrane (PEM) fuel cells. Maintaining the optimal amount of hydration can ensure that the cell is operating properly and with high efficiency. There are several components that can affect water management, however one area that has received increased attention is the interface between the gas diffusion layer (GDL) and the gas reactant channels where excess water has a tendency to build up and block reactant gasses. One key parameter that can affect this build up is the geometry of the microchannels. The work presented here proposes an optimal trapezoidal geometry which will aid in the removal of excess water in the gas channels. The Concus-Finn condition is applied to the channel surfaces and GDL to ensure the water will be drawn away from GDL surface and wicked to the top corner of the channel. An ex situ setup is designed to establish the validity of the Concus-Finn application. Once validated, this condition is then used to design optimal channel geometries for water removal in a PEM fuel cell gas channel.

In-Situ Measurement in Through-Plane Direction in PEMFC

2009 ◽  
Author(s):  
Kohei Ito ◽  
Sangkun Lee ◽  
Atsushi Yamamoto ◽  
Masaaki Hirano ◽  
Hidetaka Muramatsu ◽  
...  
Keyword(s):  
Water Management ◽  
Sensor Array ◽  
Polymer Electrolyte Membrane ◽  
Cell Voltage ◽  
Gas Diffusion ◽  
Cross Sectional ◽  
Electrolyte Membrane ◽  
Water Behavior ◽  
Plane Direction

Water management is a large issue for putting PEMFC to practical use. Appropriate water management enables us to suppress the drying in PEM (Polymer Electrolyte Membrane) and the flooding in GDL (Gas Diffusion Layer), which degrade the performance of PEMFC. Against the background of importance for the water management, we challenged to develop the measurement method to grasp the water behavior in PEMFC. Especially, we focused on through-plane direction measurement, because the through-plane direction in cell has major role for the transport of mass, heat and electric charge in the cell. We developed the three methods to measure the water in cell directly or indirectly: cross sectional cell: micro NMR-sensor array: micro thermocouple array. These three methods successively captured the distribution of the liquid water in GDL, the water content in PEM and the temperature in cell. The data obtained help us to give the possible mechanism of how the water in cell impacted the cell voltage.

Visualization of GDL Deformation by Freezing of Water Using X-Ray Radiography

2010 ◽  
Author(s):  
Jongrok Kim ◽  
Junho Je ◽  
Massoud Kaviany ◽  
Sang Young Son ◽  
Moo Hwan Kim
Keyword(s):  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Chemical Reactions ◽  
Diffusion Layer ◽  
Power Output ◽  
Operating Temperature ◽  
Polymer Electrolyte Membrane ◽  
Gas Diffusion ◽  
X Ray ◽  
Electrolyte Membrane

During operation of Polymer Electrolyte Membrane Fuel Cells (PEMFCs), electro-chemical reactions generate water, which exists as a liquid because of the PEFMC’s low operating temperature. The water remains in the PEFMC after it is turned off. During the winter this water can freeze; associated increase in its volume deforms the gas diffusion layer (GDL). The deformed GDL reduces the cell’s power output and durability. In this investigation, X-ray microscopy was used demonstrate that water freezing changed the geometry of GDL by water freezing.

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