Numerical Assessment of a 10 kW rSOC Exhaust Gas Afterburner with Preliminary Geometric Scaling Considerations

The integration of reversible solid oxide cell (rSOC) systems with industrial energy units can improve operational flexibility, but it also requires safe and efficient management of hydrogen-rich off-gas. This study presents the numerical design of an exhaust gas afterburner for a 10 kW rSOC stack, in which unreacted hydrogen mixed with steam is oxidized using the hot air stream employed for stack purging. A finite-volume CFD approach was applied using a non-premixed combustion model, a k–ω SST turbulence model, and GRI-Mech 3.0 chemistry, followed by a thermo-mechanical assessment of the chamber. For the reference case, the unreacted hydrogen stream was 1.16661 × 10−4 kg/s, corresponding to approximately 14 kW of chemical energy. The simulations predicted a localized reaction zone directly downstream of the burner outlet, accompanied by rapid hydrogen consumption and a fluid-temperature range of approximately 492–930 °C. The thermo-mechanical analysis predicted a maximum total deformation of 2.2189 mm and a maximum axial displacement of approximately 2.21 mm for the analyzed steady-state operating point. These results characterize the temperature, species, and deformation fields of the 10 kW reference configuration. The 100 kW and 1 MW variants should be treated only as preliminary geometric extrapolations, because they were not verified by separate CFD/CSD calculations.