A Numerical Study on NOx Emission by Using Micro Hydrogen Jet Flames

As exhaust gas regulations has become strick, interest in hydrogen used as a renewable energy has been increased. Recently research on low NOx emission through micro jet flame combustion methods has been carried out. In this study, multiple micro flame formation in the jet in the flow condition was assessed numerically. Particulary the flame shape and NOx emission characteristics according to the fuel-air momentum ratio were analyzed by changing the internal fuel cylinder diameter giving effects on the pressure drop and the size of the recirculation zone. Among the five momentum ratio (J) modes classified in jet in the flow geometry, the strong jet and jet dominated modes were studied in this study. In the strong jet mode, large J hardly makes the hydrogen jet deflected. On the other hand, In the case of the jet dominated mode the relatively high cross-flow momentum tends to make mixing rate suitable for making micro hydrogen flame. And the most important factor for NOx generation and emission in combustion using hydrogen fuel is considered to maintain a micro-flame using an appropriate momentum ratio.