Radiative Flame Cooling for Reduction of Nitric Oxide Emissions

Abstract

The effect of soot upon heat transfer in combusting gases is investigated. The medium considered is a turbulent gas-soot mixture contained in a plane parallel enclosure. The nongray radiative nature of the soot and the effects of the geometrical configuration are taken into account using an “internal” or “modified” slab emissivity especially developed for the purpose. The simultaneous turbulent transport and radiation are treated with full nonlinearity. It is shown that small amounts of soot greatly aid the radiative cooling of combustion gases, which undergo microrecirculation by turbulent mixing. Larger amounts of soot increase combustion temperature and hence unwanted nitric oxide emissions.