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Show constant for both the extended Zeldovich mechanism and prompt-NO~ formation route has been estimated to be ± 35% (14) and ± 18% (12) respectively. Experimental uncertainties, e.g. errors introduced in probe sampling measurement of NO concentration profiles, are very difficult to estimate. However, most importantly, model calculations indicate that by considering both turbulence/chemistry interaction and super-equilibrium 0, OH and H concentration, a good agreement can be achieved. 5.3 Concluding Remarks 1. A post-processing code for prediction of NO emissions during the combust i on process has been developed and analysed. The model is expected to provide a realistic prediction of the gas phase chemical transformation processes which leads to the formation of thermal, prompt, and fuel-NO during fossil fuel combustion. The model provides a new approach for predicting NO formation which can be used in furnace design applications without excessive computer processing time. 2. The model has been validated against experimental data from an industrial laboratory. The results show that NO formation dependency on burner geometry and combustion conditions (e.g. air/fuel ratio) has been correctly predicted. 3. Current resul ts i ndi cate that a true account of the effects of temperature and speci es f1 uctuat ions on the NO react i on rate is essent i ali n order to obta inaccurate computat i ona 1 resul ts. The developed model indicated that insight into the mixing and chemical react i on processes occurri ng in complex combust i on systems can be most readily gained by consideration of the spatial variations of joint probability density function of the mixture fraction and reaction-progress variable. 4. The predicted results indicate that in order to obtain accurate prediction of NO emission from a stationary combustor, the partial equilibrium thermochemical model which accounts for superequilibrium radical concentrations of OH, 0 and H should be considered. REFERENCES 1. Glarborg, P., Miller, J.A. and Kee, R.J. Combustion and Flame, 65, 177, 1986. 2. Bowman, C.T., Prog. Energy Combustion Sci., 1; 1989. 3. Baulch, D.L., Drysdal1, D.O., Horne, D.G. and Lloyd, A.C. Kinetic Data for High Temperature Reactions", vol. Butterworth, 1973. "Evaluated 1, 2, 3, 4. Hanson, R.K. and Sal imian, S. "Survey of Rate Constants in N/H/O System", p. 361, Combustion Chemistry, (Ed. W.C. Gardiner), 1984. 5. Bowman, C.T. Prog. Energy Combustion Sci., 1, 33, 1975. 6. Drake, M.C., Correa, S.M., Pitz, R.W., Shyy, W. and Fenimore, C.P., Combustion and Flame, 69, 347, 1987. 11 |