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We present a detailed multiphysics model capable of simulating the dynamic behavior of a solid oxide fuel cell (SOFC). This model includes a description of all the important physical and chemical processes in a fuel cell: fluid flow, mass and heat transfer, electronic and ionic potential fields, as well as the chemical and electrochemical reactions. The resulting highly nonlinear, coupled system of differential equations is solved using a finite volume discretization. Our interest lies in simulating realistic operating conditions with the objective 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 simulating operating conditions that are necessary if SOFC systems are to realize their promise of high efficiency conversion of chemical energy to electrical energy. In this report we present simulation results at operating conditions that approach the required ranges of power density and overall efficiency. Our results include a) the temperature and composition profiles along a typical fuel cell in a SOFC stack, b) the dynamic response of the cell to step changes in the available input variables. Since models such as the one presented here are fairly expensive computationally and cannot be directly used for online model predictive control, one generally looks to use simplified reduced order models for control. We briefly discuss the implications of our model results on the validity of using reduced models for the control of SOFC stacks to show that avoiding operating regions where well-known degradation modes are activated is non-trivial without using detailed multiphysics models.

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