Coupled Transport Effects in Solid Oxide Fuel Cell Modeling.

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Solid oxide fuel cells (SOFCs) show promise for energy systems.
• Accurate modeling of transport mechanisms and losses is crucial for SOFC development.
• Previous models simplified mass transport in gas diffusion layers (GDL).

Purpose of the Study:

• To improve the quantitative description of mass transport in SOFC GDLs.
• To replace Fick's law with more sophisticated models like the Dusty-Gas model (DGM) and thermal diffusion.
• To validate the enhanced model against experimental data.

Main Methods:

• Development of a 1D model based on non-equilibrium thermodynamics (NET).
• Implementation of the Dusty-Gas model (DGM) and thermal diffusion (Soret effect) for GDL mass transport.
• Validation using measured U,j-characteristics of SOFCs.

Main Results:

• The enhanced model shows a maximum deviation of 0.93% from experimental cell voltage.
• The Soret effect is negligible under prevailing conditions, but DGM is necessary.
• Peltier effects significantly influence temperature and heat flow.
• At 1123.15 K and 8000 A/m², 64.44% of losses occur in the electrolyte, with exergetic efficiency at 0.42.

Conclusions:

• The DGM provides a necessary improvement for modeling GDL mass transport in SOFCs.
• The Soret effect is not significant for the studied conditions.
• Electrolyte losses are substantial, indicating a need for alternative electrolyte materials with lower entropy production.