Numerical Simulation of SOFC System Performance at 90 Fuel Utilization with or without Anode Off-gas Recycle for Enhancing Efficiency

摘要

To investigate the possibility to enhance electrical efficiency, performance of methane-fueled 10 kW SOFC systems was numerically simulated with calculated voltage-current-density curves at 750°C of a single cell with a bipolar plate, which approximated a stack performance. Operation at 90% fuel utilization (U_f) with anode off-gas recycle (AGR) and with steam reforming (no recycle) led to 75-67 %-LHV and 72-66 %-LHV DC electrical efficiencies at 0.05-0.40 A/cm~2, respectively. System simulations considering heat loss from a stack clarified that 750°C stack temperature can be maintained at 0.12-0.40 A/cm~2 and 64-59 % and 63-59 % net AC electrical efficiency will be attainable at U_f = 90% with and without AGR, respectively. Furthermore, enhancement of net AC efficiencies was found to be 10 percentage points at those current densities against ones of a conventional system using steam reforming at U_f = 73 %.