A control-oriented dynamic model adapted to variant steam-to-carbon ratios for an SOFC with exhaust fuel recirculation

The steam-to-carbon ratio (S/C) is a typical disturbance parameter in the operation of solid oxide fuel cell (SOFC) power generation system. A planar SOFC with a pre-reformer and exhaust fuel recirculation system is investigated in this work. A lumped, nonlinear dynamic model is developed for the SOFC with consideration both of the spatial effect and the variant S/Cs. The dynamic model is deduced based on a fitting function so-called Exponential Association Function, which is employed to describe the spatial distribution of state variables in SOFC. Three parameters of the fitting function are identified to integrate the spatial effect and S/C effect in the model. The parameters of Exponential Association Function are determined by function fitting on three-dimensional numerical data at the sample operation points. Carbon formation activity is analysed using the simulation results and thermodynamic data. Dynamic simulation is implemented with the help of software MATLAB/SIMULINK. The results show that the developed model has good performance in predicting the responses of the state variables and catching the changes of S/C.