Garcia Sanchez, Daniel und Garcia Salaberri, Pablo Angel und Boillat, Pierre und Vera, Marcos und Friedrich, K. Andreas (2017) Neutron Imaging and Modelling of Autonomous Hydration-Dehydration Cycles in PEFCs Operated with Saturated Anode and Dry Cathode Feed. 7th International Conference on Fundamentals & Development of Fuel Cells, 2017-01-31 - 2017-02-02, Stuttgart, Germany.
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Kurzfassung
In this work, the current fluctuations arising in Polymer Electrolyte Fuel Cells (PEFCs) operated with wet anode and dry cathode feed (RH_a^in≈100%, RH_c^in≈5%) due to the cyclic hydration/dehydration of the membrane are examined. The analysis combines liquid water distributions obtained by neutron imaging experiments and predictions of a 3D two-phase non-isothermal model. The neutron visualizations show that the nonlinear dynamics stem from the periodic shedding of water droplets at the anode inlet chamber. As shown in Figure 1, two well-differentiated processes can be distinguished in analogy to ignition and extinction phenomena in combustion. A fast autocatalytic increase of the current (decrease of HFR) in about 20 s that goes hand-in-hand with the transport of liquid water along the anode channel (ignition), followed by a slower decrease of the current (increase of HFR) in 200 s as the accumulated water is flushed out of the cell (extinction). This challenging scenario is modeled by introducing or not introducing a steady flux of liquid water at the vapor-saturated anode inlet. As can be seen in Figure 2, the low- and high-performance states of the hydration-dehydration cycles are properly captured by the model. The low-performance state is achieved when no liquid water is assumed to enter at the anode inlet, leading to a high ionic resistance and a fairly inhomogeneous current distribution. The membrane dry-out is stronger near the cathode inlet, and decays along the cathode channel due to the membrane humidification by the anode stream. By contrast, the high-performance state is reached when a flux of liquid water is introduced at the anode inlet. The water input humidifies the cell and offsets the membrane dry-out caused by the cathode stream, leading to a low ionic resistance and a homogeneous current distribution. Two important conclusions are obtained from the work: i) liquid water injected into the anode channel is an efficient means for membrane humidification, even in the presence of a dry cathode feed, without incurring in high mass-transport losses; ii) the oscillatory hydration-dehydration regime is a useful operating scenario to study membrane resistance in durability tests.
elib-URL des Eintrags: | https://elib.dlr.de/118259/ | ||||||||||||||||||||||||
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Dokumentart: | Konferenzbeitrag (Vortrag) | ||||||||||||||||||||||||
Titel: | Neutron Imaging and Modelling of Autonomous Hydration-Dehydration Cycles in PEFCs Operated with Saturated Anode and Dry Cathode Feed | ||||||||||||||||||||||||
Autoren: |
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Datum: | 2 Februar 2017 | ||||||||||||||||||||||||
Referierte Publikation: | Nein | ||||||||||||||||||||||||
Open Access: | Nein | ||||||||||||||||||||||||
Gold Open Access: | Nein | ||||||||||||||||||||||||
In SCOPUS: | Nein | ||||||||||||||||||||||||
In ISI Web of Science: | Nein | ||||||||||||||||||||||||
Status: | veröffentlicht | ||||||||||||||||||||||||
Stichwörter: | PEFC, water management, neutron imaging, modeling, membrane, hydration-dehydration | ||||||||||||||||||||||||
Veranstaltungstitel: | 7th International Conference on Fundamentals & Development of Fuel Cells | ||||||||||||||||||||||||
Veranstaltungsort: | Stuttgart, Germany | ||||||||||||||||||||||||
Veranstaltungsart: | internationale Konferenz | ||||||||||||||||||||||||
Veranstaltungsbeginn: | 31 Januar 2017 | ||||||||||||||||||||||||
Veranstaltungsende: | 2 Februar 2017 | ||||||||||||||||||||||||
Veranstalter : | DLR | ||||||||||||||||||||||||
HGF - Forschungsbereich: | Energie | ||||||||||||||||||||||||
HGF - Programm: | Speicher und vernetzte Infrastrukturen | ||||||||||||||||||||||||
HGF - Programmthema: | Brennstoffzellen | ||||||||||||||||||||||||
DLR - Schwerpunkt: | Energie | ||||||||||||||||||||||||
DLR - Forschungsgebiet: | E SP - Energiespeicher | ||||||||||||||||||||||||
DLR - Teilgebiet (Projekt, Vorhaben): | E - Elektrochemische Prozesse (Brennstoffzellen) (alt) | ||||||||||||||||||||||||
Standort: | Stuttgart | ||||||||||||||||||||||||
Institute & Einrichtungen: | Institut für Technische Thermodynamik > Elektrochemische Energietechnik | ||||||||||||||||||||||||
Hinterlegt von: | Garcia Sanchez, Dr Daniel | ||||||||||||||||||||||||
Hinterlegt am: | 16 Jan 2018 15:37 | ||||||||||||||||||||||||
Letzte Änderung: | 24 Apr 2024 20:22 |
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