Dynamic modeling of single tubular SOFC combining heat/mass transfer and electrochemical reaction effects

In this paper, a dynamic model of a single tubular solid oxide fuel cell (SOFC) unit is developed using the control volume (CV) approach. The heat transfer, species transportation, and electrochemical reaction effects are taken into account in a collective manner. Using this model, we study the spatial distributions of a series of state variables under both steady-state and transient operations and evaluate the system dynamic behavior. The analysis shows that there exists non-uniform current contribution and Nernst potential distribution along the longitudinal direction, caused by the non-uniform fuel/gas partial pressures along the flow direction and the temperature distribution in the anode/cathode channel and cell body, for example. The classical Nernst potential relation is revised to capture the characteristics of the fuel cell under time varying external load voltage. Comprehensive numerical simulations are carried out to explore the underlying dynamic properties in typical SOFC operations. The numerical study is also correlated to experimental results such as the polarization curve and power density, which shows good agreement.