Correlation of In Situ and Ex Situ Measurements of Water Permeation Through Nafion NRE211 Proton Exchange Membranes | Zendy

Makoto Adachi | Zendy; Titichai Navessin | Zendy; Zhong Xie | Zendy; Barbara J. Frisken | Zendy; Steven Holdcroft | Zendy

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Correlation of In Situ and Ex Situ Measurements of Water Permeation Through Nafion NRE211 Proton Exchange Membranes

Author(s) -

Makoto Adachi,

Titichai Navessin,

Zhong Xie,

Barbara J. Frisken,

Steven Holdcroft

Publication year - 2009

Publication title -

journal of the electrochemical society

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 1.258

H-Index - 271

eISSN - 1945-7111

pISSN - 0013-4651

DOI - 10.1149/1.3116922

Subject(s) - permeation , membrane , water vapor , water transport , nafion , chemistry , proton exchange membrane fuel cell , analytical chemistry (journal) , relative humidity , chemical engineering , chromatography , electrode , electrochemistry , water flow , environmental engineering , thermodynamics , organic chemistry , biochemistry , physics , engineering

Water permeability at 70°C is determined for Nafion NRE211 membrane exposed to either liquid or vapor phases of water. Chemical potential gradients of water across the membrane are controlled through use of differential humidity (38―100% RH) in the case of water vapor and hydraulic pressure (0―1.2 atm) in the case of liquid water. Accordingly, three types of water permeation are defined: vapor-vapor permeation, liquid-vapor permeation (LVP), and liquid-liquid permeation. The difference in chemical potentials across the membrane, and more significantly, the flux of water, is largest when the membrane is exposed to liquid on one side and vapor on the other (i.e., LVP conditions). Polarization curves and net water fluxes are reported for NRE211-based MEAs at 70°C under two different operating conditions. Water permeability measurements obtained ex situ are compared to fuel cell water balance measurements obtained in situ. It is found that the magnitude of back-transport of water during fuel cell operation can be explained only by considering that the membrane is exposed to liquid on one side and vapor on the other (i.e., LVP conditions). Thus, LVP water transport is largely responsible for regulating water balance within the operating membrane electrode assembly.

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