A PARAMETRIC STUDY OF NO2 EMISSION FROM TURBULENT H-2 AND CH4 JET DIFFUSION FLAMES

Nitrogen dioxide (NO2) emission levels of fuel jets were experimentall y studied for H-2, H-2/He mixtures, a H-2/He/CH4 mixture, and CH4. The study was undertaken to understand the dependence of NO2 emission in turbulent diffusion flames on parameters other than the widely known e ffects of rapid mixing. These parameters are fuel types (CH4 vs H-2), the initial NO level, and the flame temperature. The fuel mixtures wer e chosen such that these factors could be investigated independently. In all the flames studied, NO2/NOx increases with decreasing NO concen tration in the flame and with decreasing adiabatic flame temperature. The CH4 fuel demonstrates a qualitatively different influence on the N O2/NOx ratio than H-2. Its effects are most pronounced when the flame blowout limit is approached. Adding a small amount of CH4 to the H-2 f lames also qualitatively affected the NO2/NOx ratio. (C) 1998 by The C ombustion Institute.