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

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.

PEMFC on line diagnosis via acoustic emission measurements � 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

PEMFC on line diagnosis via acoustic emission measurements Diagnosis, state of health ? Control Corrective or preventive actions Detection of the failures Measures (sensors) Identification Inlet Oulet Process 3

PEMFC on line diagnosis via acoustic emission measurements ● Fuel cell External I circuit H 2 in O 2in Anode Cathode H 2 + ½ O 2 → H 2 O H 2 → 2 H + + 2 e - ½ O 2 + 2 H + + 2 e - → H 2 O H 2 out O 2out + H 2 O ● Development of diagnosis strategies ◆ Reliability ◆ Durability ● “ Monitoring ” in real-time and “in situ” of fuel cell under operation 4

PEMFC on line diagnosis via acoustic emission measurements Acoustic emission AE energy release within a material in the form of a transient elastic waves. Acquisition, storage Piezoelectric sensor and analysis R15 or WD (PCI-2 AEWin, Preamplifier Noesis) tunable 2/4/6 EA : 20 – 1200 kHZ AE a promising tool to non destructive analysis of the fuel cell ? 5

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

PEMFC on line diagnosis via acoustic emission measurements Monitoring in real-time and “in situ” Two studied scales: - Nafion membrane dehydration, - Fuel cell (one cell of 25 cm 2 ). 7

PEMFC on line diagnosis via acoustic emission measurements 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

PEMFC on line diagnosis via acoustic emission measurements Nafion membrane dehydration Follow-up of the dehydration of Nafion by : - acoustic emission - mass loss measurement - electrochemical impedance spectroscopy 9 9

PEMFC on line diagnosis via acoustic emission measurements Nafion membrane dehydration Follow-up of the mass of the membrane and the EA according to time 1 EA activity M/M0 0,9 0,8 0,7 Drying 0,6 0,5 0,4 0,3 0,2 0,1 0 0 2000 4000 6000 8000 temps (s) B. Legros, R. P. Nogueira, P. -X. Thivel, S. Maximovitch, F. Druart, Y. Bultel, M. Boinet, 10 " 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),

PEMFC on line diagnosis via acoustic emission measurements Nafion membrane dehydration Follow-up of the conductivity (EIS) and the EA according to time 0.05S.cm -1 0.00063S.cm -1 Membrane conductivity (left) and cumulated AE activity (right) versus drying time at 70° C and 10% RH. B. Legros, P-X Thivel, Y Bultel, M Boinet, R Nogueira, "Electrochemical impedance and acoustic emission survey of water desorption in Nafion membranes", 11 11 Electrochemical and solide state letters , 12 (7) B116-B118 (2009)

PEMFC on line diagnosis via acoustic emission measurements 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 12

PEMFC on line diagnosis via acoustic emission measurements 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

PEMFC on line diagnosis via acoustic emission measurements 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

PEMFC on line diagnosis via acoustic emission measurements Merci de votre attention Takk for oppmerksomheten Thanks for your attention 15