Thermal Contact Resistance Measurements of Compressed PEFC Gas Diffusion Media

2016 ◽  
Vol 13 (4) ◽  
Author(s):  
Adam S. Hollinger ◽  
Stefan T. Thynell
Keyword(s):  
Fuel Cell ◽  
Contact Resistance ◽  
Pressure Range ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Gas Diffusion ◽  
Temperature Gradients ◽  
Polymer Electrolyte Fuel Cell ◽  
Carbon Paper ◽  
Carbon Cloth

Localized temperature gradients in a polymer electrolyte fuel cell (PEFC) are known to decrease the durability of the polymer membrane. The most important factor in controlling these temperature gradients is the thermal contact resistance at the interface of the gas diffusion layer (GDL) and the bipolar plate. Here, we present thermal contact resistance measurements of carbon paper and carbon cloth GDLs over a pressure range of 0.7–14.5 MPa. Contact resistances are highly dependent upon the clamping pressure applied to a fuel cell, and in the present work, contact resistances vary from 3.5 × 10−4 to 2.0 × 10−5 m2 K/W, decreasing nonlinearly over the pressure range for each material tested. The contact resistances of carbon cloth GDLs are two to four times higher than contact resistances of carbon paper GDLs throughout the range of pressures tested. The data presented here also show that the thermal resistance of the sample is negligible in comparison to the thermal contact resistance. Controlling temperature gradients in a fuel cell is desirable, and the measurements presented here can be used to more accurately predict temperature distribution in a polymer electrolyte fuel cell.

Thermal Contact Resistance Measurements of Gas Diffusion Layers in Polymer Electrolyte Fuel Cells

2015 ◽  
Author(s):  
Adam S. Hollinger ◽  
Stefan T. Thynell
Keyword(s):  
Fuel Cell ◽  
Contact Resistance ◽  
Polymer Electrolyte ◽  
Pressure Range ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cell ◽  
Gas Diffusion Layers ◽  
Diffusion Layers

Localized temperature gradients in a polymer electrolyte fuel cell are known to decrease the durability of the polymer membrane. The most important factor in controlling these temperature gradients is the thermal contact resistance at the interface of the gas diffusion layer and the bipolar plate. Here we present thermal contact resistance measurements of carbon paper and carbon cloth gas diffusion layers over a pressure range of 0.7–14.5 MPa. Contact resistances are highly dependent upon the clamping pressure applied to a fuel cell, and in the present work, contact resistances vary from 3.5E−4 to 2.0E−5 m2K/W, decreasing non-linearly over the pressure range for each material tested. The data presented here also shows that the thermal resistance of the sample is negligible in comparison to the thermal contact resistance. Thermal uniformity in a fuel cell is desirable, and the measurements presented here can be used to more accurately predict temperature distribution in a polymer electrolyte fuel cell.

scholarly journals Effect of Compression on the Effective Thermal Conductivity and Thermal Contact Resistance in PEM Fuel Cell Gas Diffusion Layers

2010 ◽  
Author(s):  
Ehsan Sadeghi ◽  
Ned Djilali ◽  
Majid Bahrami
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Fuel Cell ◽  
Contact Resistance ◽  
Effective Thermal Conductivity ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Pem Fuel Cell ◽  
Gas Diffusion ◽  
Analytical Models

Heat transfer through the gas diffusion layer (GDL) of a PEM fuel cell is a key process in the design and operation a PEM fuel cell. The analysis of this process requires determination of the effective thermal conductivity as well as the thermal contact resistance between the GDL and adjacent surfaces/layers. In the present study, a guarded-hot-plate apparatus has been designed and built to measure the effective thermal conductivity and thermal contact resistance in GDLs under vacuum and atmospheric pressure. Toray carbon papers with the porosity of 78% and different thicknesses are used in the experiments under a wide range of compressive loads. Moreover, novel analytical models are developed for the effective thermal conductivity and thermal contact resistance and compared against the present experimental data. Results show good agreements between the experimental data and the analytical models. It is observed that the thermal contact resistance is the dominant component of the total thermal resistance and neglecting this phenomenon may result in enormous errors.

scholarly journals Transport Parameter Correlations for Digitally Created PEFC Gas Diffusion Layers by Using OpenPNM

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1141
Author(s):  
Ángel Encalada-Dávila ◽  
Mayken Espinoza-Andaluz ◽  
Julio Barzola-Monteses ◽  
Shian Li ◽  
Martin Andersson
Keyword(s):  
Fuel Cell ◽  
Energy Conversion ◽  
Transport Phenomena ◽  
Electrical Energy ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cell ◽  
Carbon Paper ◽  
Transport Parameter ◽  
Transport Parameters ◽  
Depth Analysis

A polymer electrolyte fuel cell (PEFC) is an electrochemical device that converts chemical energy into electrical energy and heat. The energy conversion is simple; however, the multiphysics phenomena involved in the energy conversion process must be analyzed in detail. The gas diffusion layer (GDL) provides a diffusion media for reactant gases and gives mechanical support to the fuel cell. It is a complex medium whose properties impact the fuel cell’s efficiency. Therefore, an in-depth analysis is required to improve its mechanical and physical properties. In the current study, several transport phenomena through three-dimensional digitally created GDLs have been analyzed. Once the porous microstructure is generated and the transport phenomena are mimicked, transport parameters related to the fluid flow and mass diffusion are computed. The GDLs are approximated to the carbon paper represented as a grouped package of carbon fibers. Several correlations, based on the fiber diameter, to predict their transport properties are proposed. The digitally created GDLs and the transport phenomena have been modeled using the open-source library named Open Pore Network Modeling (OpenPNM). The proposed correlations show a good fit with the obtained data with an R-square of approximately 0.98.

In-Plane Microstructure of Gas Diffusion Layers With Different Properties for PEFC

2013 ◽  
Author(s):  
Mehdi Mortazavi ◽  
Kazuya Tajiri
Keyword(s):  
Contact Angle ◽  
Fuel Cell ◽  
Pore Diameter ◽  
Gas Transport ◽  
Gas Permeability ◽  
Transport Phenomena ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cell ◽  
Diameter Distribution ◽  
Carbon Paper

Gas diffusion layer (GDL) is undoubtedly one of the most complicated components used in a polymer electrolyte fuel cell (PEFC) in terms of liquid and gas transport phenomena. An appropriate fuel cell design seeks a fundamental study of this tortuous porous component. Currently, porosity and gas permeability have been known as some of the key parameters affecting liquid and gas transport through GDL. Although these are dominant parameters defining mass transport through porous layers, there are still many other factors affecting transport phenomena as well as overall cell performance. In this work, microstructural properties of Toray carbon papers with different thicknesses and for polytetrafluoroethylene (PTFE) treated and untreated cases have been studied based on scanning electron microscopy (SEM) image analysis. Water droplet contact angle as a dominant macroscale property as well as mean pore diameter, pore diameter distribution, and pore roundness distribution as important microscale properties have been studied. It was observed that the mean pore diameter of Toray carbon paper does not change with its thickness and PTFE content. Mean pore diameter for Toray carbon papers was calculated to be around 26μm regardless of their thicknesses and PTFE content. It was also observed that droplet contact angle on GDL surface does not vary with GDL thickness. The average contact angle for 10 wt.% PTFE treated GDLs of different thicknesses was measured about 150°. Finally, the heterogeneous in-plane PTFE distribution on the GDL surface was observed to have no effect on mean pore diameter of GDLs.

An X-Ray Tomography Based Lattice Boltzmann Simulation Study on Gas Diffusion Layers of Polymer Electrolyte Fuel Cells

2010 ◽  
Vol 7 (3) ◽  
Author(s):  
Pratap Rama ◽  
Yu Liu ◽  
Rui Chen ◽  
Hossein Ostadi ◽  
Kyle Jiang ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Lattice Boltzmann ◽  
Gas Diffusion ◽  
Transport Processes ◽  
Polymer Electrolyte Fuel Cell ◽  
Absolute Permeability ◽  
Carbon Paper ◽  
X Ray ◽  
Microscale Transport

This work reports a feasibility study into the combined full morphological reconstruction of fuel cell structures using X-ray computed micro- and nanotomography and lattice Boltzmann modeling to simulate fluid flow at pore scale in porous materials. This work provides a description of how the two techniques have been adapted to simulate gas movement through a carbon paper gas diffusion layer (GDL). The validation work demonstrates that the difference between the simulated and measured absolute permeability of air is 3%. The current study elucidates the potential to enable improvements in GDL design, material composition, and cell design to be realized through a greater understanding of the nano- and microscale transport processes occurring within the polymer electrolyte fuel cell.

In-Plane Microstructure of Gas Diffusion Layers With Different Properties for PEFC

2013 ◽  
Vol 11 (2) ◽  
Author(s):  
Mehdi Mortazavi ◽  
Kazuya Tajiri
Keyword(s):  
Contact Angle ◽  
Fuel Cell ◽  
Pore Diameter ◽  
Gas Transport ◽  
Gas Permeability ◽  
Transport Phenomena ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cell ◽  
Carbon Paper ◽  
The Mean

The gas diffusion layer (GDL) is undoubtedly one of the most complicated components used in a polymer electrolyte fuel cell (PEFC) in terms of liquid and gas transport phenomena. An appropriate fuel cell design seeks a fundamental study of this tortuous porous component. Currently, porosity and gas permeability have been known as some of the key parameters affecting liquid and gas transport through the GDL. Although these are dominant parameters defining mass transport through porous layers, there are still many other factors affecting the transport phenomena and overall cell performance. In this work, the microstructural properties of Toray carbon papers with different thicknesses and for polytetrafluoroethylene (PTFE) treated and untreated cases have been studied based on scanning electron microscopy (SEM) image analysis. The water droplet contact angle, as a dominant macroscale property, along with the mean pore diameter, pore diameter distribution, and pore roundness distribution, as important microscale properties, have been studied. It was observed that the mean pore diameter of Toray carbon paper does not change with its thickness and PTFE content. Mean pore diameter for Toray carbon papers was calculated to be around 26μm, regardless of their thicknesses and PTFE content. It was also observed that the droplet contact angle on the GDL surface does not vary with the GDL thickness. The average contact angle for the 10 wt. % PTFE treated GDLs of different thicknesses was measured at about 150 deg. Finally, the heterogeneous in-plane PTFE distribution on the GDL surface was observed to have no effect on the mean pore diameter of GDLs.

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