Direct pore-level simulation of ammonia combustion in multi-zone porous media burners

Ammonia is a promising fuel for decarbonization of the energy infrastructure. However, NH3
exhibits poor combustion characteristics. Blending with reactive fuels like H2 can improve
the flame stability of NH3 at the expense of higher NOx emissions. Another approach is
porous media combustion (PMC), where the gaseous mixture is burned in a solid matrix.
Heat recirculation between the upstream fuel/air and the reaction zone can improve the flame
stability of NH3 flames and enable burner operation with lower NOx emissions. In this work,
a multi-zone porous media burner is considered. The porous zones are comprised of triplyperiodic
minimal surface (TPMS) gydroid and diamond structures. Comprehensive sub-models
for conjugate heat transfer (CHT) and radiation are integrated in an in-house 3D solver. The
effects of porosity, topology and material properties of the porous structures on flame stabilisation
and pollutant emissions are investigated through direct pore-level simulations (DPLS).
The inlet boundary conditions are set to obtain a flame that stabilises in the TPMS-diamond
structures and NH3/air is preheated in the gyroidal section.