Ammonia is a carbon-free fuel for micro-power, yet its low reactivity and high NO x hinder stable micro-combustion. This study develops a unified simulation framework coupling detailed NH 3 /Pt surface chemistry with gas-phase kinetics to quantify how Pt catalysis, staged coating, cavity-induced recirculation, and partial NH 3 cracking jointly widen the stable low-emission window. Fuel-NO dominates at equivalence ratio (ER) = 1.0 (76–92% for cracking ratio (CR) = 0–90%), whereas at ER = 0.6 thermal-NO is important at low CR but fuel-NO regains dominance as CR increases. In Pt-coated microchannels, gas-phase combustion sustains up to ∼8 m/s; a 1.0mm spacing maintains >1700 K, while ≤0.4 mm quenches. A cavity-assisted staged design raises the critical velocity to 13 m/s by enhancing recirculation and OH retention. A Taguchi L 16 optimization (including a NO-per-conversion-gradient metric) identifies inlet velocity, spacing, and cavity depth as dominant factors; CR = 30% achieves full conversion early with comparatively low NO emission. • CFD couples gas-phase and Pt-surface kinetics for NH 3 microchannel combustion. • Fuel-NO dominates NO x (76–92%) at ER = 1.0; at ER = 0.6, thermal-NO leads at low CR. • TA identifies inlet velocity, microchannel width, and cavity depth as key factors. • The maximum fuel conversion rate is 0.313 %/mm with 2 mm(L) × 0.2 mm(D) cavity. • The lowest NO emission normalized by fuel conversion rate occurs at CR 90%.
Chen et al. (Tue,) studied this question.