, D.
, Duewer, D.
, Spernjak, D.
, Weber, A.
, Mukundan, R.
, Fairweather, J.
, Brosha, E.
, Davey, J.
, Spendelow, J.
and Borup, R.
(2021),
Accurate measurement of the through-plane water content of proton-exchange membranes using neutron radiography, Journal of Physical Chemistry B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=911111
(Accessed January 19, 2025)
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Accurate measurement of the through-plane water content of proton-exchange membranes using neutron radiography
Published
Author(s)
, , Dusan Spernjak, Adam Weber, Rangachary Mukundan, Joseph Fairweather, Eric Brosha, John Davey, Jacob Spendelow, Rodney Borup
Abstract
The water sorption of proton-exchange membranes (PEMs) was measured in situ using high-resolution neutron imaging in small-scale fuel-cell test sections. A detailed characterization of the measurement uncertainties and corrections associated with the technique is presented. The developed image-processing procedure resolved a previously reported discrepancy between the measured and predicted membrane water content. With high-resolution neutron-imaging detectors, the water distributions across N1140 and N117 Nafion membranes are resolved in vapor-sorption experiments and during fuel-cell and hydrogen-pump operation. The measured in situ water content of a restricted membrane at 80 °C is shown to agree with ex situ gravimetric measurements of free-swelling membranes over a water activity range of 0.5 to 1.0 including at liquid equilibration. Schroeder's paradox was verified by in situ water-content measurements which go from a high value at supersaturated or liquid conditions to a lower one with fully saturated vapor. At open circuit and during fuel-cell operation, the measured water content indicates that the membrane is operating between the vapor- and liquid-equilibrated states.Citation
Journal of Physical Chemistry B
Pub Type
Journals
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Keywords
nafion, neutron radiography, proton exchange membrane fuel cell, Schroeder's paradox, water sorption
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Created April 21, 2021, Updated May 3, 2021