Formation of Oxides of Nitrogen in Monodisperse Spray Combustion of Hydrocarbon Fuels

Droplet Size Effects on NOx Formation in a One-Dimensional Monodisperse Spray Combustion System

“…Also, it appears that, while the NO x minimum points are not sharply defined in the current data, the methanol minima are shifted to slightly larger droplet diameters and the n-heptane and n-octane data are shifted to slightly smaller droplet diameters relative to isopropanol. These general trends are in agreement with the theoretical calculations and the experimental data reported by Nizami et al (1982) in their aerodynamically stabilized flame measurements. Thus, since aerodynamic and mixing effects have been minimized in the current system, these results and behavior indicate a true droplet size effect on NO x formation.…”

“…The apparent shifts in the droplet diameters associated with the NO minimum points for the various fuels were found to be consistent with the thermophysical properties of the fuels; some of these thermophysical properties and evaporation parameters, as reported by Nizami et al (1982), are given in Table 1.…”

“…The evaporation constants and extent of prevaporization for the different fuels were calculated and compared following the approach used by Nizami et al (1982). The procedure yields reasonable relative results for extent of prevaporization prior to the fuel spray reaching the flame zone.…”

“…At an equivalence ratio, of 1.39, a 61% reduction in NO x and a 87.5% reduction in NO were observed from the maximum values recorded in the two respective modes. These studies were extended later to include five additional hydrocarbon fuels with similar results (Nizami, 1978;Nizami et al, 1982). Typically, NO x reductions at the optimum droplet diameter were in the range of 40-70 percent and the optimum droplet diameter occurred from 48-55 microns.…”

“…Under these conditions, the relative importance of heterogeneous and homogeneous effects in dominating the combustion process is switched and gives rise to a number of interesting and important effects. For example, maxima in burning velocities (Polymeropoulos and Das, 1975;Hayashi et al, 1976), extension of flammability limits (Burgoyne and Cohen, 1954), minima in ignition energies (Rao and Lefebvre, 1973;Ballal and Lefebvre, 1978;Chan and Polymeropoulos, 1981), and minima in pollutant emissions (Nizami andCernansky, 1978, 1979;Nizami et al, 1982) have all been observed and reported. These transition region effects have been reviewed and discussed by Nisami et al (1982).…”