PEMFC on line diagnosis via acoustic emission measurements B. - - PowerPoint PPT Presentation

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PEMFC on line diagnosis via acoustic emission measurements

• B. Legros, P.-X. Thivel*, Y Bultel, R.P. Nogueira

Laboratory of electrochemistry and physico-chemistry of materials and interfaces (LEPMI) Science and engineering of materials and process (SIMAP)

* Ass. Prof : University Joseph Fourier, Grenoble, France.

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Diagnosis, state of health ? Acoustic emission Nafion membrane dehydration Fuel cell (one cell of 25 cm2)

Conclusions

Future research activities within diagnostic tools for fuel

cell technologies PEMFC on line diagnosis via acoustic emission measurements

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Diagnosis, state of health ?

Process Inlet Oulet Measures (sensors) Control Corrective or preventive actions Detection of the failures Identification

PEMFC on line diagnosis via acoustic emission measurements

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• Development of diagnosis strategies

◆ Reliability ◆ Durability

• “Monitoring” in real-time and “in situ” of fuel cell under operation
• Fuel cell

H2 in O2in O2out+ H2O H2 out External circuit I Anode H2 → 2 H+ + 2 e- Cathode ½ O2 + 2 H+ + 2 e-→ H2O

H2 + ½ O2 → H2O

PEMFC on line diagnosis via acoustic emission measurements

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Acoustic emission

AE energy release within a material in the form of a transient elastic waves.

EA : 20 – 1200 kHZ Piezoelectric sensor R15 or WD Preamplifier tunable 2/4/6 Acquisition, storage and analysis (PCI-2 AEWin, Noesis)

PEMFC on line diagnosis via acoustic emission measurements

AE a promising tool to non destructive analysis of the fuel cell ?

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• Number of events
• For each event :
• amplitude
• rise time
• duration of the event
• number of counts

Characteristic signal of phenomena or failure

Acoustic emission PEMFC on line diagnosis via acoustic emission measurements

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Monitoring in real-time and “in situ”

Two studied scales:

• Nafion membrane dehydration,
• Fuel cell (one cell of 25 cm2).

PEMFC on line diagnosis via acoustic emission measurements

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Nafion : polymeric matrix where SO3 groups form ionic clusters, connected to each other by channels. Structure very different according to the degree from hydration

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10%w

Nafion membrane dehydration PEMFC on line diagnosis via acoustic emission measurements

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Follow-up of the dehydration of Nafion by :

• acoustic emission
• mass loss measurement
• electrochemical impedance spectroscopy

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Nafion membrane dehydration PEMFC on line diagnosis via acoustic emission measurements

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Follow-up of the mass of the membrane and the EA according to time

0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 2000 4000 6000 8000 temps (s) M/M0

Drying EA activity

Nafion membrane dehydration PEMFC on line diagnosis via acoustic emission measurements

• B. Legros, R. P. Nogueira, P. -X. Thivel, S. Maximovitch, F. Druart, Y. Bultel, M. Boinet,

" Initial results for the application of the acoustic emission technique on a PEMFC Membrane", Fundamentals and Developments of Fuel Cell Conference, Nancy, 10-12 décembre (2008),

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11 Membrane conductivity (left) and cumulated AE activity (right) versus drying time at 70° C and 10% RH. 0.05S.cm-1 0.00063S.cm-1

Follow-up of the conductivity (EIS) and the EA according to time Nafion membrane dehydration

• B. Legros, P-X Thivel, Y Bultel, M Boinet, R Nogueira, "Electrochemical impedance and

acoustic emission survey of water desorption in Nafion membranes", Electrochemical and solide state letters, 12 (7) B116-B118 (2009)

PEMFC on line diagnosis via acoustic emission measurements

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Objectives :

• To approach the source of acoustic emission events
• To ensure an effective acoustic coupling

Fuel cell (one cell of 25 cm2)

EA sensor : in contact with bipolar plate

PEMFC on line diagnosis via acoustic emission measurements

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αO2 = 1,7 αH2 = 1,7

Set point V = 0,43 V I = 25 A

Fuel cell (one cell of 25 cm2) PEMFC on line diagnosis via acoustic emission measurements Results are still under analysis

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• Diagnosis of the state of the membrane

◆ Hydration/Swelling of the membrane

• Diagnosis of PEMFC under operative conditions

◆ Specific activity under current condition

• Perspectives

◆ Cracking in the assembly ? ◆ Water droplet formation and flooding ? ◆ Heating point ? Conclusions PEMFC on line diagnosis via acoustic emission measurements

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PEMFC on line diagnosis via acoustic emission measurements Merci de votre attention Takk for oppmerksomheten Thanks for your attention