PEMFC on line diagnosis via acoustic emission measurements. B. Legros, P.-X. Thivel*, Y Bultel, R.P. Nogueira

Transcription

1 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) 1 * Ass. Prof : University Joseph Fourier, Grenoble, France.

2 Diagnosis, state of health? Acoustic emission Nafion membrane dehydration Fuel cell (one cell of 25 cm 2 ) Conclusions Future research activities within diagnostic tools for fuel cell technologies 2

3 Diagnosis, state of health? Control Corrective or preventive actions Measures (sensors) Detection of the failures Identification Inlet Process Oulet 3

4 Fuel cell H 2 in External circuit I O 2in Anode H 2 2 H e - H 2 out Cathode ½O H e - H 2 O O 2out + H 2 O H 2 + ½ O 2 H 2 O Development of diagnosis strategies Reliability Durability Monitoring in real-time and in situ of fuel cell under operation 4

5 Acoustic emission PEMFC on line diagnosis via acoustic emission measurements AE energy release within a material in the form of a transient elastic waves. Piezoelectric sensor R15 or WD EA : khz Preamplifier tunable 2/4/6 Acquisition, storage and analysis (PCI-2 AEWin, Noesis) AE a promising tool to non destructive analysis of the fuel cell? 5

6 Acoustic emission PEMFC on line diagnosis via acoustic emission measurements - Number of events - For each event : - amplitude -rise time - duration of the event - number of counts Characteristic signal of phenomena or failure 6

7 Monitoring in real-time and in situ Two studied scales: - Nafion membrane dehydration, - Fuel cell (one cell of 25 cm 2 ). 7

8 Nafion membrane dehydration Nafion : polymeric matrix where SO 3 groups form ionic clusters, connected to each other by channels. Structure very different according to the degree from hydration 10%w 8 8

9 Nafion membrane dehydration Follow-up of the dehydration of Nafion by : - acoustic emission - mass loss measurement - electrochemical impedance spectroscopy 9 9

10 Nafion membrane dehydration Follow-up of the mass of the membrane and the EA according to time M/M0 1 0,9 EA activity 0,8 0,7 0,6 Drying 0,5 0,4 0,3 0,2 0, temps (s) 10 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, décembre (2008),

11 Nafion membrane dehydration Follow-up of the conductivity (EIS) and the EA according to time 0.05S.cm S.cm -1 Membrane conductivity (left) and cumulated AE activity (right) versus drying time at 70 C and 10% RH. 11 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)

12 Fuel cell (one cell of 25 cm 2 ) EA sensor : in contact with bipolar plate Objectives : - To approach the source of acoustic emission events - To ensure an effective acoustic coupling 12

13 Fuel cell (one cell of 25 cm 2 ) α O2 = 1,7 α H2 = 1,7 Set point V = 0,43 V I = 25 A Results are still under analysis 13

14 Conclusions 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? 14

15 Merci de votre attention Takk for oppmerksomheten Thanks for your attention 15