Characterizing heat transfer within a commercial-grade tubular solid oxide fuel cell for enhanced thermal management

A thermal transport model has been developed for analyzing heat transfer and improving thermal management within tubular solid oxide fuel cells (TSOFCs). The model was constructed via a proven electrochemical model and well-established heat transfer correlations. Its predictions compare favorably with other published data. Air temperatures consistently approach that of the fuel cell. This is primarily due to the high operating temperature of the cell (1000°C), the moderate magnitudes of radiation and airflow, and cell geometry. The required inlet air temperature (for thermally steady-state operation) has linear dependence on operating voltage and fuel utilization. Inlet air temperature has an inverse proportionality with respect to air stoichiometric number (i.e., inverse equivalence ratio). The current standard for airflow within TSOFCs was found to be excessive in consideration of the regenerative preheat effect within the supply pipes that feed air to the cell. Thermal management of simple TSOFC systems could be enhanced if commonly used air stoichiometric numbers were decreased.