Experimentally and numerically study on NH3/H2/Air combustion characteristics in micro non-premixed swirling combustor

Zero-carbon fuel-fired micro-thermophotovoltaic (MTPV) systems are widely concerned for their high energy density and environmental friendliness. As a typical zero-carbon blended fuel, improving the combustion stability and safety of NH3/H2 is crucial for the system. Therefore, a micro non-premixed swirling combustor for NH3/H2/Air was proposed. A visual experimental platform and 3D numerical model coupled with detailed chemical reaction mechanism was established. The combustion and emission characteristics of NH3/H2/Air in this combustor were experimentally and numerically investigated. The flame morphology, thermal performance, exhaust pollutant emissions, and radiation efficiency were comprehensive investigated by varying the NH3 blending ratio (Br = 0∼0.8), equivalence ratio (Er = 0.7∼1.1) and input power (Pin = 400∼700 W). The results indicated that the inlet parameters exert dual effects on the NH3/H2/Air non-premixed swirling combustion. One of them is the inhibitory effect induced by variations in ammonia content, and the other is gas mixing process driven by the flow field. With the increase of Pin and Er, the inhibitory effect caused by the variation of NH3 content became stronger. As Br increased, the gas mixing process driven by the flow field gradually dominated. As Pin increased, the maximum flame temperature rose, reaching 1031 K at Pin = 700 W. NO distribution along the centerline could be divided into the reaction core zone and the mild zone, and both of them regulated by fuel NO and thermal NO. The maximum radiation efficiency of 50.1% under optimal operating condition was obtained which is Br = 0.8, Er = 0.8, and Pin = 500 W.