Numerical study on non-premixed combustion characteristics of NH3/O2 in multi-inlet micro combustor

In recent years, Micro Thermophotovoltaic (MTPV) devices using NH3 have attracted much attention due to their high energy density, small size and carbon-free. A novel micro non-premixed combustor with multi-inlet is presented. A 2D model of non-premixed micro combustion in multi-inlet micro combustor coupled with NH3/O2 mechanism was established. The ignition position and flame front position of non-premixed flame were discussed. The effect of inlets arrangement, total flow velocity, diameter ratio, and transverse distance of each fuel inlets on the thermal and emission performance was numerically investigated. The results showed that the flame position and flame temperature are the two main factors affecting NO emissions. Increasing the ignition point and ignition area can make the flame more uniform with lower temperature, which aids in NO emission reduction. However, the average temperature of the outer wall decreases. The average wall temperature in the multi-inlet combustor increases by 6.72 % from 1324 K to 1413 K when compared to the literature. The mass fraction of NO in the exhaust decreases by 14.46 % from 2.35 x 10-2 kmol/m3 to 2.01 x 10-2 kmol/m3. The total radiation energy of outer wall increases from 63.9 W to 75.7 W.