A spatially resolved physical model for transient system analysis of high temperature fuel cells

This work builds upon previous high temperature fuel cell (HT-FC) modeling studies, capturing both steady state performance and transient behavior of HT-FC stacks by merging simplified dimensional aspects of a planar fuel cell stack with first principles physical modeling. Dynamic simulations are developed that spatially resolve fluctuations in temperature, pressure and concentration distributions during transient operation. A significant portion of the heat transfer occurs prior to and after the air passes over the electrochemically active portions of the cell, justifying additional heat transfer pathways from the stack to the air in order to accurately characterize the thermal transients and temperature distributions in the HT-FC stack. The highly configurable MatLab-Simulink® model developed can simulate both solid oxide and molten carbonate fuel cells utilizing either direct or indirect internal reforming. The perturbation response characteristics of the dynamic model to load, fuel flow, air flow and composition perturbations are discussed, and control strategies are introduced that minimize temperature fluctuations. Analysis indicates air flow and inlet temperature controls are sufficient to control average temperature and average internal temperature gradients. Internal heat transfer dynamics substantially change the spatial temperature distribution and local temperature gradients during typical operating conditions and perturbations.