Department News
Study for the Characteristics of the Gas Diffusion Layers and Their Effects on P
Seminar Date
2004-06-23
Author
임아주
Date
2004-06-23
Views
1774
1. 제 목
Study for the Characteristics of the Gas Diffusion Layers and Their Effects on PEMFC Performance
2. 연 사
Woo-Kum Lee
Research Assistant Proffessor
Department of Chemical Engineering College of Engineering and Information Technology
3. 일 시 : 2004년 7월 1일 목요일 오후 4시
4. 장 소 : 301동 1512호 세미나실
5. 내 용
The proton exchange membrane fuel cell (PEMFC) is regarded as highly attractive for mobile and residential applcations due to high power density, high efficiency, and low temperature operation. The PEMFC use a gas diffusion layer(GDL) to distribute reactants to anode and cathode at areas that are orthogonal to the bulk flow but parallel to the membrane. This distribution is necessary because most flow field designs use ribs that separate the flow channels to provide lectrical contact between the current collectors and electrodes. Thus, the electrical conductivity of these layers may affect the transport of electrons in the cell. Also, the permeability of the gas diffusion layer may affect the mass transport in reaction areas. The mass transfer limitation depends on the permeability of the GDL that is generally compressible and may have hydrophobic/hydrophilic characteristics, which influence fuel cell performance by affecting the degree of hydration of the membrane, the formation of liquid water, and the water transport across the membrane. The objectives of study are to measure fundamental properties of gas diffusion layers(GDL) and to characterize the performance of these GDL during operation in a PEMFC.
One focus of the study is to investigate the effect of the compression that results when a cell is assembled. That is, the thickness and the porosity of commercially available GDL can change depending on the thickness of the gasket and the degree to which the gasket is compressed as the cells are clamped together. After cell assembled, a lower porosity would increase the gas phase mass transfer resistance. On the other hand, higher compression may increase the overall electron conductivity of the GDL, improve the contact resistance in the cell, and hence, minimize some of the electrical resistance losses inside the cell. Another focus in the study is to apply techniques for measuring contact angles on porous media and determine how these techniques might be used to quantify the hydrophobic/hydrophilic nature of each GDL. In the experiment, the Water/Mercury Intrusion Porosimeter(Porous Materials Inc.) was employed to measure the hydrophobic and hydrophilic pores in the sample. The instrument measured pore volume and pore diameter of samples using water and mercury as intrusion liquids.
6. 문 의 : 기계항공공학부 민 경 덕 교수 (880-7108)
Study for the Characteristics of the Gas Diffusion Layers and Their Effects on PEMFC Performance
2. 연 사
Woo-Kum Lee
Research Assistant Proffessor
Department of Chemical Engineering College of Engineering and Information Technology
3. 일 시 : 2004년 7월 1일 목요일 오후 4시
4. 장 소 : 301동 1512호 세미나실
5. 내 용
The proton exchange membrane fuel cell (PEMFC) is regarded as highly attractive for mobile and residential applcations due to high power density, high efficiency, and low temperature operation. The PEMFC use a gas diffusion layer(GDL) to distribute reactants to anode and cathode at areas that are orthogonal to the bulk flow but parallel to the membrane. This distribution is necessary because most flow field designs use ribs that separate the flow channels to provide lectrical contact between the current collectors and electrodes. Thus, the electrical conductivity of these layers may affect the transport of electrons in the cell. Also, the permeability of the gas diffusion layer may affect the mass transport in reaction areas. The mass transfer limitation depends on the permeability of the GDL that is generally compressible and may have hydrophobic/hydrophilic characteristics, which influence fuel cell performance by affecting the degree of hydration of the membrane, the formation of liquid water, and the water transport across the membrane. The objectives of study are to measure fundamental properties of gas diffusion layers(GDL) and to characterize the performance of these GDL during operation in a PEMFC.
One focus of the study is to investigate the effect of the compression that results when a cell is assembled. That is, the thickness and the porosity of commercially available GDL can change depending on the thickness of the gasket and the degree to which the gasket is compressed as the cells are clamped together. After cell assembled, a lower porosity would increase the gas phase mass transfer resistance. On the other hand, higher compression may increase the overall electron conductivity of the GDL, improve the contact resistance in the cell, and hence, minimize some of the electrical resistance losses inside the cell. Another focus in the study is to apply techniques for measuring contact angles on porous media and determine how these techniques might be used to quantify the hydrophobic/hydrophilic nature of each GDL. In the experiment, the Water/Mercury Intrusion Porosimeter(Porous Materials Inc.) was employed to measure the hydrophobic and hydrophilic pores in the sample. The instrument measured pore volume and pore diameter of samples using water and mercury as intrusion liquids.
6. 문 의 : 기계항공공학부 민 경 덕 교수 (880-7108)
