Parametric analysis of a solid oxide fuel cell auxiliary power unit operating on syngas produced by autothermal reforming of hydrocarbon fuels

A 1 kW_e integrated auxiliary power unit (APU) system consisting of an autothermal reformer and a solid oxide fuel cell (SOFC) unit, as well as balance-of-plant components, was designed and analyzed. A relatively easy-to-approach SOFC model was developed in order to conveniently calculate V-I and P-I curves and the system's net efficiency at different operating conditions. The effects of steam to carbon and oxygen to carbon ratios in the reactants, channel dimensions of the SOFC unit, and hydrocarbon fuel types on the integrated APU system's performance were discussed. Five hydrocarbon fuels including diesel, Jet-A, gasoline, ethanol, and methanol were studied as fuel sources for the APU system. The system's net efficiency around 35% is possible for all the tested fuels in the current density range of 100-400 mA/cm². The APU system was also verified to be thermally self-sustainable in the steady state operation by a thermal management analysis.