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Measurement of spatially resolved impedance spectroscopy with local perturbation

 
: Zamel, N.; Bhattarai, A.; Gerteisen, D.

:

Fuel Cells 13 (2013), No.5, pp.910-916
ISSN: 1615-6846
ISSN: 1615-6854
English
Journal Article
Fraunhofer ISE ()
Energietechnik; Wasserstoff- und Brennstoffzellentechnologie; Brennstoffzellensysteme; Cells; Impendance Spectroscopy; Spatially Resolved Measurement

Abstract
The characteristics of the measured total impedance spectra of polymer electrolyte membrane fuel cells are often not representative of the performance of the cell. This is due in part mainly to two reasons; total impedance measurements are not representative of local phenomena and perturbation of the cell around the steady-state polarization can result in oscillations of the gas concentrations downstream the flow channels that can affect the trend of the local spectrum. In this study, we overcome these two challenges by measuring the spectra of a segmented cell using local excitation of the segments. With these capabilities, we experimentally investigate the explanation given in works found in literature in regards to the oxygen oscillation in the channel and its effect on the spectra of locally perturbed segments. We further investigate the characteristics of the low frequency arc, measuring for the first time a loop in the spectrum around the transition frequency betw een the high and low frequency arcs. The characteristics of the spectra are investigated by varying the flow properties with a focus on the effect of air stoichiometry.

: http://publica.fraunhofer.de/documents/N-254761.html