Flame structure and NOx emission characteristics in a single hydrogen combustor

• Published in: International journal of hydrogen energy 2022-08, Vol.47 (68), p.29542-29553
• Main Authors: Choi, Jaehong, Ahn, Myunggeun, Kwak, Sanghyeok, Lee, Jong Guen, Yoon, Youngbin
• Format: Article
• Language: English
• Subjects: Emission; Hydrogen; Micromixer; Residence time; Swirl
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2022.06.247

In this study, the effects of fuel-induced swirl number on the flame structure and NOx emissions are observed. A tube-type nozzle with four fuel injection holes is used. The fuel injection holes are located away from the centerline of the nozzle to induce a low swirl effect in the flow. First, the flame structure changes with the fuel-induced swirl number, separating into four small flames in the high-swirl region; the flames are classified into three types. Subsequently, NOx emissions decrease with an increase in the fuel-induced swirl number. However, this shows a stepwise discontinuous change rather than a gradual change. The NOx emission is linearly proportional to the residence time of the combustion gas, which is calculated using the flame volume and flame structure. In conclusion, the change in the flame structure by the fuel-induced swirl is a decisive factor in the reduction of the NOx. [Display omitted] •The tangential fuel injection nozzle induce a weak swirl in the flow.•Effects of swirl number on flame structure and NOx emission.•Flame structure shifted with swirl number.•Reduction of NOx emission in use of Hydrogen as fuel achieved.