1. R. Zaera Universidad Carlos III de Madrid
This work has been partially supported by project ENE C03-02 of the spanish Ministerio de Ciencia e Innovación
An anisotropic nonlinear FEM model of the inhomogeneous compression of PEMFC gas diffusion layers
P. A. García-Salaberri
M. Vera
R. Zaera Universidad Carlos III de Madrid

2. Outline Motivation FEM Model Description Validation Results
Hypothesis
Geommetry
Mechanical Charaterization
Validation
Results
Conclusions
Future Work
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

3. Motivation Fuel cell assembly Nitta [1]
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

4. Model Description: Geometry
Reference geometry
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

5. Model Description: Hypothesis
Elastic GDL deformation
Large deformation theory
Plane strain
Non-linear orthotropic properties
Imposed through-plane deformation
Gasket thickness
GDL affected by membrane deformation
Hygro-thermal cycling
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

6. Mechanical Charaterization
BP → linear elastic, isotropic
E = 10 GPa, ν = 0.25
GDL → non-linear elastic, orthotropic
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

7. GDL Mechanical Characterization
Ex & Ez
Gxy
Kleemann et al. [2]
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

8. GDL Mechanical Characterization
E y(εy)
Ey (Mpa) εy
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

9. Porosity and Diffusivity Fields
Porosity field
Diffusivity field (e.g. Brugemann correction)
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

10. Non-linear Orthotropic model
Model Validation
Porosity field
Non-linear Orthotropic model
Present work
Isotropic model
Zhou et al. [8,9]
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

11. Model Validation Channel intrusion Lai et al. [7] Present work
Kandlikar [6]
Present work
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

12. BP Width Ф WBP WBP Intrusion
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

13. GDL Thickness tGDL Ф tGDL Intrusion Similar effect to Gxy
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

14. Orthotropic vs. Isotropic Models
Isotropic models may lead to incorrect predictions
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

15. Membrane Swelling (I) Nafion membrane Model parameters →
Linear-elasto-plastic with isotropic hardening
T and RH dependent properties [10]
Model parameters →
Homogeneus BP, GDL & membrane temperature
Homogeneus RH in the membrane
Tassembly = 20ºC RHassembly = 30%
Toperation = 85ºC RHoperation = 100%
Kusoglu et al. [10]
Assembly
Operation
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

16. Membrane Swelling (II)
Membrane swelling decreases porosity and improves contact resistances during FC operation
Operation
Assembly
Operation
Assembly
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

17. Conclusions
A non-linear orthotropic FEM model has been developped to study the effects of inhomogeneous compression in PEMFC GDLs during FC assembly and operation
Parametric studies
Geom. parameters: BP width, GDL thickness
Mech. properties: Ex, Ez, Gxy, Orthotrop./Isotropic
Isotropic models may lead to incorrect predictions
Membrane swelling ↓ porosity and ↓contact resistances during FC operation
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

18. Future Work
Evaluate the effect of inhomogeneous GDL compression in fuel cell performance
Effect of variable porosity on
Effective diffusion coefficients
Multiphase transport
Water transport in PEMFC
CO2 transport in DMFC
BP-GDL / membrane-GDL contact resistances
Channel obstruction due to GDL intrusion
Hygro-thermal membrane loading
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M

19. References
[1] Nitta (2008) Inhomogeneous compression of PEMFC gas diffusion layers, Doctoral dissertation, Helsinki (Finland). [2] Kleemann, Finsterwalder & Tillmetz (2009) J. Power Sources 190:92–102. [3] Mathias, Roth, Fleming & Lehnert (2003) in Handbook of Fuel Cells–Fundamentals, Technology and Applications, Volume 3: Fuel Cell Technology and Applications, Chapter 46, W. Vielstich, H.A. Gasteiger, A. Lamm (Editors), John Wiley & Sons, Ltd. [4] Matsuura, Kato & Hori (2006) J. Power Sources 161:74–78. [5] Escribano, Blachot, Ethève, Morin & Mosdale (2006) J. Power Sources 156:8–13. [6] Kandlikar, Lu, Lin, Cooke & Daino (2009) J. Power Sources 194:328–337. [7] Lai, Rapaport, Ji & Kumar (2008) J. Power Sources 184:120–128. [8] Zhou, Wu & Ma (2006) J. Power Sources 159:115–1122. [9] Zhou, Wu & Ma (2007) J. Power Sources 163:874–881. [10] Kusoglu, Karlsson, Santare, Cleghorn & Johnson (2007) J. Power Sources 170:345–358.
Session 1B – 06/10/ P.A. García-Salaberri, M. Vera & R. Zaera – UC3M