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Simulazione dettagliata
della resistenza ohmica
per celle IP-SOFC
Laura Repetto, Paola Costamagna
Genova, 12 Dicembre 2007
Università di Genova
Dipartimento di Ingegneria Chimica e di Processo ‘G.B. Bonino’
Summary of the work carried out
AIM
Detailed simulation of the ohmic losses of the IP-SOFC (Integrated
Planar-Solid Oxide Fuel Cell) and calculation of the ohmic resistance.
HOW
Numerical solution of partial differential equations through the
commercial software Comsol Multiphisycs.
WHAT I DID
 Development of a physical / matematical model
 Model validation
 Use of the model to predict the IP-SOFC performance
Genova, 12 Dicembre 2007
Solid Oxide Fuel Cell (SOFC)
Solid Oxide Fuel Cell (SOFC) is a particular
Fuel Cell characterized by the use of a
ceramic electrolyte (a solid oxide). The
electrochemical reactions are:
1 O2  2e  O 
2
Cathodic reaction
H 2  O  H 2O  2e Anodic reaction
Tubular geometry
Planar geometry
Genova, 12 Dicembre 2007
IP-SOFC
The IP-SOFC concept is a proprietary SOFC design currently developed by
Rolls-Royce Fuel Cell Systems Ltd.
tubular geometry
+
planar geometry
IP-SOFC geometry
Mechanical stability of the
cell components
e-
Lower manufacturing
costs
e-
Simplified IP-SOFC geometry
NOTE: the electrochemical reactions on cathodic and anodic side have not been simulated
Genova, 12 Dicembre 2007
Model equations
 i 2Vi  0 i where i  1,2,3,4,5 is the index of a cell "subdomain"
n J  J n normal current density
n J  0 electrical insulation
n (J i  Ji )  0  i1, i2  1,2,3,4,5
1
continuity along the interfaces
2
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Comsol Multiphysics
• Comsol Multiphysics is a modelling package able to simulate the
physical process described with partial differential equations
(PDEs).
• It is based on the finite elements method (FEM).
• It is an interactive environment.
• It provides specialised modules with predefined PDEs for different
scientific fields (in my work the Electromagnetics Module and in
particular the Conductive Media DC section has been used).
• These modules use standardized terminology and material
libraries. Usually it is not necessary to write the equations since
they are included in the modules; it is sufficient to describe the
physical/mathematical properties of the problem (materials
conductivity, continuity of the solution along the interfaces etc)
Genova, 12 Dicembre 2007
Comsol results (1)
Norma della densità di corrente nell’elettrolita
Femlab
Matlab
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Comsol results (2)
e-
e-
Colour map of the Voltage
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Comsol results (3)
e-
e-
Streamlines and colour map of the current density norm
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Model predictions
Model validation
Model prediction
Geometry optimisation
Design the optimal geometry in
order to increase the performance
of the cell and, at the same time,
to lower manufacturing costs.
Work carried out:
 study of the current path in the
electrolyte
Secondary interconnect
(SIC) study
Design the optimal geometry of the
secondary interconnect in order to
increase the performance of the
cell and, at the same time, to lower
manufacturing costs.
 study of the current path in the
cathodic and anodic collectors
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Geometry optimisation (2)
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Future work
 Simulation of new geometries.
 Optimisation study.
 Complete model including ohmic, activation and concentration losses.
Publications
 Laura Repetto, Gerry Agnew, Adriana Del Borghi, Fabio Di Benedetto, Paola Costamagna.
“Detailed Simulation of the Ohmic Resistance of SOFCs”: Journal of Fuel Cell Science and
Technology; volume 4, issue 4, pp 413-417.
 S. Grosso, L. Repetto, P. Costamagna. “IP-SOFC model”, chapter 9 of the book “Modeling Solid
Oxide Fuel Cells: Methods, Procedures and Techniques”, editor R. Bove, Springer, in press.
 Laura Repetto, Paola Costamagna. “FEM Model of the Ohmic Resistance of IP-SOFCs”: Journal
of Applied Electrochemistry; submitted.
Genova, 12 Dicembre 2007
Thank you for your attention
Genova, 12 Dicembre 2007