We present a detailed multiphysics model capable of simulating the dyn
amic behavior
of a solid oxide fuel cell (SOFC). This model includes a description of a
ll the important physical
and chemical processes in a fuel cell: fluid flow, mass and heat trans
fer, electronic and ionic
potential fields, as well as the chemical and electrochemical react
ions. The resulting highly
nonlinear, coupled system of differential equations is solved using a fi
nite volume discretization.
Our interest lies in simulating realistic operating conditions with the obj
ective of high efficiency
operation at high fuel utilization. While there are a number of studies
in the literature that
present multiphysics models for SOFCs, few have focused on simulat
ing operating conditions
that are necessary if SOFC systems are to realize their promise of h
igh efficiency conversion of
chemical energy to electrical energy. In this report we present s
imulation results at operating
conditions that approach the required ranges of power density an
d overall efficiency. Our results
include a) the temperature and composition profiles along a typical f
uel cell in a SOFC stack, b)
the dynamic response of the cell to step changes in the available inpu
t variables. Since models
such as the one presented here are fairly expensive computationa
lly and cannot be directly used
for online model predictive control, one generally looks to use simplifie
d reduced order models
for control. We briefly discuss the implications of our model results o
n the validity of using
reduced models for the control of SOFC stacks to show that avoid
ing operating regions where
well-known degradation modes are activated is non-trivial without u
sing detailed multiphysics
models
