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Author(s): M. Navasa, M. Andersson, J. Yuan & B. Sundén
Abstract:
Solid oxide fuel cells (SOFCs) are promising candidates for future energy systems
due to their ability to use renewable fuels and that they are energy efficient.
A fully
coupled two-dimensional computational fluid dynamics (CFD) model based on
the finite element method (using COMSOL Multiphysics) is developed to describe
an intermediate temperature SOFC single cell.
Governing equations for various
transport processes including heat, mass, momentum and charge transport (ion
and electron) are implemented and coupled with the chemical and electrochemical
reactions that take place inside the cell.
The chemical and electrochemical reactions are strongly bonded to heat transfer
being special contributors to the global and local energy balances of the cell.
Thus, the effect of methane in the fuel composition on the reaction rate focusing
on the polarizations is studied.
When considering a mixture of carbon monoxide
and hydrogen as the electrochemically active fuels, a lower open circuit voltage
is observed, which means lower activation polarizations, increased reaction rates
and an increase in the temperature difference of the whole cell unit.
Consequently,
by reducing the methane concentration, less methane steam reforming is required
which leads to a higher cell temperature difference increasing the electrochemical
reaction rate.
Nevertheless, high temperature gradients introduce mechanical
stresses and material degradation which may cause cell failure.
Keywords: SOFC, CFD, fuel, carbon monoxide, hydrogen, activation polarizations,
current density.
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Pages: 12
Size: 496 kb
Paper DOI: 10.2495/HT120011
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This paper can be found in the following book Advanced Computational Methods and Experiments in Heat Transfer XII Buy
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