reference29 - 2334 J. Electrochem. Soc., Vol. 138, No. 8,...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 2334 J. Electrochem. Soc., Vol. 138, No. 8, August 1991 The Electrochemical Society, Inc. 5. U n io n C arbide Corporation, C arbon P roducts Division (now A M O CO P e r f o r m a n c e Products), Technical In- form ation Bulletins 465-223,465-225, 465-246. 6. P. Wagner, J. Am. Ceramic Soc., 55, 214 (1971). 7. O. M. Baycura, IEEE Trans. Indust., 5, 208 (1968). 8. K. K inoshita and S. C. Leach, This Journal, 129, 1993 (1982). 9. "C h em ical E ngineers H a n d b o o k ," 5th ed., R. H. P erry and C. H. Chilton, McGraw-Hill, N e w Y ork (1973). 10. W. L. I n g m a n s o n et aI., TAPPI, 42, 840 (1959). Polymer Electrolyte Fuel Cell Model T. E. Springer,* T. A. Zawodzinski,* and S. Gottesfeld* Los Alamos National Laboratory, Los Alamos, New Mexico 87545 A B S T R A C T We present here an isotherm al, one-dim ensional, steady-state m o d el for a co m p lete p o ly m e r electrolyte fuel cell (PEFC) w ith a 117 Nation | m e m b ra n e . In this m o d e l w e e m p lo y w ater diffusion coefficients electro-osm otic drag coeffi- cients, w ater sorption isotherm s, and m e m b r a n e conductivities, all m easured in our laboratory as functions of m e m b r a n e w ater content. T he m o d e l pre.dicts a net-w ater-per-proton flux ratio of 0.2 H20/H § u n d er typical operating conditions, w h ich is m u c h less than the m e a s u re d electro-osm otic drag coefficient for a fully hydrated m em b ran e. It also predicts an increase in m e m b r a n e resistance w ith increased current density and dem onstrates the great advantage of a th in n e r m em - brane in alleviating this resistance problem . B oth of these predictions w ere verified ex p erim en tally u n d e r certain condi- tions. F u el cells e m p lo y in g hydrated Nation or other hydrated perfluorinated io n o m eric m aterials as the electrolyte are prom ising candidates for electric vehicle applications (1). T he p o ly m e r electrolyte provides r o o m te m p e ra tu re start- up, elim ination o f m a n y corrosion problem s, and the po- tential for low resistance losses. Resistive losses w ithin the fuel cell result, in part, from the decrease of m e m b r a n e protonic c o n d u c tiv ity follow ing partial dehydration of the m em b ran e. On the other hand, cathode flooding problem s are caused w h e n too m u c h w ater is in the system. Clearly, w ater m a n a g e m e n t w ithin the fuel cell involves w alking a tightrope b e tw e e n the two extrem es. Spatial variations of w ater content w ithin the polym eric electrolyte of a current~carrying fuel cell result from the electro-osm otic dragging of w ater w ith proton transport from anode to cathode, the p ro d u ctio n of w ater by the oxy- gen red u ctio n reaction at the cathode, hum idification con- ditions of the inlet gas streams, and "back-diffusion" of w ater from cathode to anode, w h ic h lessens the concentra- tion gradient....
View Full Document

This note was uploaded on 10/28/2010 for the course EE 89 taught by Professor Asgarian during the Fall '10 term at Amirkabir University of Technology.

Page1 / 9

reference29 - 2334 J. Electrochem. Soc., Vol. 138, No. 8,...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online