Browsing by Author "Yan, W. M."

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An analytical solution for transport of oxygen in cathode gas diffusion layer of PEMFC
(2006-09-29)
Tsai, C. R.
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Chen, Falin
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Ruo, A. C.
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Chang, Min-Hsing
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Chu, Hsin-Sen
A two-dimensional theoretical model is developed in this study to simulate the transport phenomena of oxygen in cathode gas diffusion layer (GDL) of proton exchange membrane fuel cell (PEMFC). An analytical solution is then obtained accordingly to characterize the effects of GDL on cell performance. It is found that the concentration flux of oxygen across the GDL is primarily dominated by the thickness and porosity of GDL. For a thicker GDL, the diffusion resistance increases and thus lowers the cell performance especially under high current density condition. On the other hand, an increase of porosity will enhance the transport of oxygen and result in significant improvement of cell performance. The influences of system parameters including the temperature, channel height, inlet velocity, and inlet pressure on the diffusion of oxygen in GDL are also examined systematically. Results provide insights into the characteristics of oxygen diffusion in GDL and benefit the optimal design of PEMFC. (c) 2006 Elsevier B.V. All rights reserved.
Reactant gas transport and cell performance of proton exchange membrane fuel cells with tapered flow field design
(2006-07-14)
Liu, H. C.
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Yan, W. M.
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Soong, C. Y.
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Chen, Falin
;
Chu, H. S.
The objective of this work is to examine the reactant gas transport and the cell performance of a proton exchange membrane fuel cell (PEMFC) with a tapered flow channel design. It is expected that, with the reduction in the channel depth along the streamwise direction, the reactant fuel gas in the tapered channel can be accelerated as well as forced into the gas diffuser layer to enhance the electrochemical reaction and thus augment the cell performance. The effects of liquid water formation on the reactant gas transport are taken into account in the present study. Numerical predictions show that the cell performance can be enhanced with the fuel channel tapered, and the enhancement is more noticeable at a lower voltage. The results also reveal that the liquid water effect in general influences the cell performance and the effect becomes significant at lower voltages. (c) 2005 Elsevier B.V. All rights reserved.
Transient behavior of CO poisoning of the anode catalyst layer of a PEM fuel cell
(2006-09-22)
Chu, H. S.
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Wang, C. P.
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Liao, W. C.
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Yan, W. M.
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機械工程學系
A one-dimensional transient mathematical model is applied to simulate the carbon monoxide poisoning effect on the performance of a PEM fuel cell. Based on the CO kinetic model developed by Springer et al. [T.E. Springer, T. Rockward, T.A. Zawodzinski, S. Gottesfeld, J. Electrochem. Soc. 148 (2001) A11-A23], the transient behaviors of the CO poisoning process across the anode catalyst layer is investigated. The results show that the hydrogen coverage, OH, decreases with the time due to CO adsorption on the catalyst sites. A higher CO concentration results in fewer available catalyst sites for hydrogen electro-oxidation and a significant decrease in the response time to reach steady state, t(ss). Increasing the anode overpotential and the gas porosity would result in an increase in the current density, especially at low levels of CO concentration. (c) 2006 Elsevier B.V. All rights reserved.