Local Online Gas Analysis in PEFC Local Online Gas Analysis in PEFC - PowerPoint PPT Presentation

Local Online Gas Analysis in PEFC Local Online Gas Analysis in PEFC G. Schuler, A. Wokaun, F. N. Büchi Electrochemistry Laboratory, Fuel Cell Systems Paul Scherrer Institut 5232 Villigen / Switzerland

Outline • Measurement Concepts of Local Online Gas Analysis • Hardware description • Applications • Summary 2 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Motivation Why do we investigate the local gas phase Why do we investigate the local gas phase in PEF in PEFC: • Most mass transport processes in PEFC are related to gaseous species or transport in the gas phase: • Reactant transport in porous media • Gas permeation through the membrane • Focus: Better understanding of local gas phase properties cal gas phase properties and transp transport proces ort processe ses under realistic operating conditions realistic operating conditions. • Need for appropriate hardware to investigate temporal and local changes of the gas phase. 3 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

L oc al Gas E xtr ac tion in 3 Dime nsions 4 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Me asur e me nt Conc e pts: X Dir e c tion 5 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Me asur e me nt Conc e pts: Y Dir e c tion 6 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Me asur e me nt Conc e pts: Z Dir e c tion 7 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Ce ll De sign • 200 cm 2 active area • Fused silica capillaries: • 11 Gas port within the flow field • internal diameter 50 μ m • 2 integral gas ports (feed and outlet) • max. 37 μ l/min gas extraction 8 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Gas Analysis Ove r vie w 9 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Gas Analysis Ove r vie w 10 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Quality of the Gas E xtr ac tion Syste m 11 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Quality of the Gas E xtr ac tion Syste m Quality of Gas Extraction S Quality of Gas Extraction System: stem: • Air leakage limits trace gas analysis flexibility (no trace gas analysis of N 2 , O 2 ) • Restrictive peak analysis allows for sufficient fuel cell investigation accuracy 12 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Wate r Vapor Me asur e me nt Water Vapo Water Vapor M r Meas asuremen ement: t: • Identical ionization probability of N2 and H 2 O for electron impact ion sources simplify water calibration [1]. • Comparison with capacitive humidity sensor (Vaisala HMP247). • Absolute humidity error < 2% within the relevant humidity range of rH 20% to rH 100% and lies within the error of the humidity sensor. [1] A. Karlegärd, A. Götz, I. Bjerle, Chem. Eng. Technol. 18 (2004) 183-192. 13 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Wate r Vapor Me asur e me nt Cou Counterflow opera erflow operation ion T cell : 80°C cell Load: Load: 0.375 A/cm 2 Anode: Anode: 90% H2, 10% He, rH 46%, p a =1.5 bar, λ = 3 Membrane: Membrane: N112 Cathode: Cathode 100% Air, rH 50%, p c =1.5 bar, λ = 2 Electrode Electrode: ETek ELAT A6 V2.1 14 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

OCV He lium Pe r me ation Me asur e me nt OCV OCV condition condition Membrane: Membrane: Nafion fion 112 Electrod ectrode: e: Etek Elat A6V2.1 An Anode: 90% H2 90% H2, 1 10% He He V=0.5 l n /min T cell c He P He Equival Equi valent nt P P H2 cell He He H2 rH rH 46% 46% [°C] [ppm] [mol/m/s/Pa] [mol/m/s/Pa] p a = 1.5 bar 40 400 2.5E-14 5.8E-15 Cathode: Cathode: 100% Air 100% Ai 60 577 3.6E-14 8.3E-15 V=0.5 l n /min rH rH 50% 50% 80 770 4.8E-14 1.1E-14 p c = 1.5 bar 15 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

OCV He lium Pe r me ation Me asur e me nt Membrane: Membrane: Nafion 112 Electrode Electrode: Etek Elat A6V2.1 T cell : 80°C cell Anode: Anode: 90% H2, 10% He rH 46% p a = 1.5 bar Cathode Cathode: 100% Air rH 50% p c = 1.5 bar 16 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

Summar y Local Online Local Online Gas A Gas Analy alysis is in PEF in PEFC: •High flexibility: • measurement concepts • operating conditions •Linear fuel cell of technical size •Mass spectrometry based system •Local online gas species investigation: • dry gas species • water vapor 17 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009

18 Diagnostic Tools For Fuel Cell Technologies, Trondheim 2009