Effect of radiation on nitric oxide concentration under sooting oxy-fuel conditions

摘要

The effect of soot radiation on NO formation in laminar, counter-flow, CH_4/O_2/N_2 oxy-fuel flames is studied by varying the N_2 content in both the oxidizer and fuel streams. Quantitative LSF measurements of [NO] are compared to predictions obtained by considering gas-phase radiation, both without and with soot radiation. Predicted peak soot volume fractions of 6 to 10 ppm are found to be consistent with a local temperature near 1500 K. Comparisons of [NO] measurements with computations indicate excellent agreement in regions of the flames for which temperatures are below 2600 K. However, some disagreement is observed at higher temperatures near peak NO locations, although the inclusion of a soot formation and radiation model improves the agreement. For our flame conditions, enhanced radiative heat loss owing to soot formation decreases peak flame temperatures by only ～10 K and thus peak NO concentrations by less than 6%.