Numerical analysis of an SOFC stack under loss of oxidant related fault conditions using a dynamic non-adiabatic model

This paper presents a numerical analysis of a 1000 W-class solid oxide fuel cell stack. The study includes simulation of dynamic operation of the unit under conditions which are qualified as faults. The simulation tool was developed to address the effects of oxidant-related faults on the operating parameters of the stack. Additionally, a control system was proposed in order to mitigate the effects of the sudden reduction in the flow of oxidant and passivation of the cells inside a 60-cell stack. In the current study, those occurrences were related to the loss of tightness of the sealants in the stack of planar cells. The model of an adiabatic-stack was used to generate the temperature profiles and was used in two reference cases. In the first case, the control system was activated in order to maintain the key parameters within the safe range, in the second case the simulations with deactivated controls enabled prediction of the temperature, voltage and power in the stack which continues operation without counteractions oriented toward minimizing the negative impacts on the performance due to exceeding the given limiting values of parameters. In the current study, two scenarios were analyzed: partial loss of oxidant and partial failure of stack modules resulting in decrease of the generated electric power. The results of both cases are presented, with and without the fault prevention control modules considered. Adjustment of the operating parameters can effectively limit the rapid increase in thermal gradients inside the stack. To complement the discussion, a classification of the typical faults of SOFC stack is presented.