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

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

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

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  • G. Schuler, A. Wokaun, F. N. Büchi

Electrochemistry Laboratory, Fuel Cell Systems Paul Scherrer Institut 5232 Villigen / Switzerland

Local Online Gas Analysis in PEFC Local Online Gas Analysis in PEFC

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Outline

  • Measurement Concepts of Local Online Gas Analysis
  • Hardware description
  • Applications
  • Summary
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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

  • rt processe

ses under realistic operating conditions realistic operating conditions.

  • Need for appropriate hardware to investigate temporal and local

changes of the gas phase.

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L

  • c al Gas E

xtr ac tion in 3 Dime nsions

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Me asur e me nt Conc e pts: X Dir e c tion

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Me asur e me nt Conc e pts: Y Dir e c tion

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Me asur e me nt Conc e pts: Z Dir e c tion

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Ce ll De sign

  • 200 cm2 active area
  • 11 Gas port within the flow field
  • 2 integral gas ports (feed and outlet)
  • Fused silica capillaries:
  • internal diameter 50μm
  • max. 37μl/min gas extraction
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Gas Analysis Ove r vie w

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Gas Analysis Ove r vie w

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Quality of the Gas E xtr ac tion Syste m

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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 N2

, O2 )

  • Restrictive peak analysis allows for sufficient fuel cell investigation accuracy
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Wate r Vapor Me asur e me nt Water Vapo Water Vapor M r Meas asuremen ement: t:

  • Identical ionization probability of N2

and H2 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

  • f the humidity sensor.

[1] A. Karlegärd, A. Götz, I. Bjerle, Chem. Eng. Technol. 18 (2004) 183-192.

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Wate r Vapor Me asur e me nt

Anode: Anode: 90% H2, 10% He, rH 46%, pa =1.5 bar, λ = 3 Cathode Cathode: 100% Air, rH 50%, pc =1.5 bar, λ = 2 Cou Counterflow opera erflow operation ion Tcell

cell

: 80°C Load: Load: 0.375 A/cm2 Membrane: Membrane: N112 Electrode Electrode: ETek ELAT A6 V2.1

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OCV He lium Pe r me ation Me asur e me nt

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 ln /min rH rH 46% 46% pa = 1.5 bar Cathode: Cathode: 100% Ai 100% Air V=0.5 ln /min rH rH 50% 50% pc = 1.5 bar

Tcell

cell

[°C]

cHe

He

[ppm]

PHe

He

[mol/m/s/Pa]

Equi Equival valent nt P PH2

H2

[mol/m/s/Pa]

40 400 2.5E-14 5.8E-15 60 577 3.6E-14 8.3E-15 80 770 4.8E-14 1.1E-14

OCV OCV condition condition

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OCV He lium Pe r me ation Me asur e me nt

Membrane: Membrane: Nafion 112 Electrode Electrode: Etek Elat A6V2.1 Tcell

cell

: 80°C Anode: Anode: 90% H2, 10% He rH 46% pa = 1.5 bar Cathode Cathode: 100% Air rH 50% pc = 1.5 bar

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Summar y Local Online Local Online Gas A Gas Analy alysis is in PEF in PEFC:

  • Linear fuel cell of technical size
  • Mass spectrometry based system
  • Local online gas species investigation:
  • dry gas species
  • water vapor
  • High flexibility:
  • measurement concepts
  • operating conditions
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