STRUCTURE OF OPPOSED JET FLAME AND NO-CHI FORMATION

High-intensity premixed combustion (0.71 - 1.12x10(9) kJ/m(3)h) was achieved using an opposed jet burner. The NOx emission was measured by an NO/NOx chemiluminescence analyzer. Maximum NOx formation measured was extremely low and varied from 20 ppm to 40 ppm, depending on the combustion intensity. Such a low NOx formation is attributed to the short residence time and the structure of the distributed reaction zone. The equivalence ratio at which NOx is maximized was found to be 1.3. The temperature dependence of NOx concentration can be given empirically by an Arrhenius expression, and the apparent activation energy is small compared with that of the Zel'dovich mechanism. On the basis of these results, we can conclude that the contribution from the Zel'dovich mechanism is suppressed in the distributed reaction zone and that the NOx originating from prompt NO is predominant.