Dynamic model of planar solid oxide fuel cells for steady state and transient performance analysis

With its high efficiency and low emissions, Solid Oxide Fuel Cell (SOFC) is a promising alternative solution for many applications including both stationary power plants and mobile Auxiliary Power Unit (APU) systems. In this paper, a dynamic model is developed for planar co-flow SOFCs for both transient and steady-state performance analysis. Finite volume method with user-defined grid is adopted to deal with the spatial distributions of current densities, pressures, temperatures and gas compositions in the SOFC. Simulations of both transient and steady state behaviors are performed to analyze the system performance. Fuel utilization, air excess ratio, air inlet temperature and current density are identified as critical operating parameters for steady-state performance in terms of cell efficiency, maximum temperature and temperature gradient in the Positive electrode-Electrolyte-Negative electrode (PEN) structure. Dynamic responses to step changes of fuel and air flow rates (two important control variables) and responses to the step change in load (the main disturbance) are analyzed to shed lights on feedback control design.