Roles of radiation reabsorption on flame speed and NO emission during ammonia combustion with syngas blending at elevated pressures

The radiative properties of NH3 and CO have considerable effects on ammonia-syngas flames, which has not been investigated at present. Radiation reabsorption effects on flame speed and NO production of one-dimensional premixed ammonia/syngas/air laminar flames were studied, encompassing a wide syngas content range and elevated pressures up to 25 atm. The improvement of flame speeds by radiation reabsorption reached 25.9% and decreased with rising syngas content, controlled by the direct-radiation effect and the reaction NH2 + NO = N2H + OH (R287). The relative enhancement of NO production decreased from 19.7% to 1.1% with increasing syngas content, affected by N + OH = NO + H (R273). The radiation reabsorption increased the flame speed by 25% at 18 atm. The coupling impact of high pressure and radiation reabsorption on flame speed was dominated by NH + NO = N2O + H (R279) and R287 via NH and OH radicals, respectively.