Main reaction zone in fuel-rich systems

2 Main reaction zone in fuel-rich systems 

The burning velocity, and the temperature and composition profiles in a low temperature, fuel-rich hydrogen—nitrogen—oxygen flame at atmospheric pressure having an unbumt gas composition 2, u = 0.1883, A N2,u 0.7657 and Aqj.u = 0.0460, with = 336 K, were measured by Dixon-Lewis et al. [156] while the burning velocities of a number of flames having compositions not too far from this were also examined by Dixon-Lewis and co-workers [158, 159]. In a number of these flames the main reaction zone extended from approximately 600—1060 K, and the predominantly recombination zone from about 1060—1080 K. The maxi- 

Rate coefficients from hydrogen—oxygen flames [168]  

Since the ratio 2fe2/ 4 is reliably known from second explosion limit work, the three kinetic unknowns in the system are now 3/ 20 smd 17. Again initially, 2 was assigned the fixed value 2.05 x 10 exp (—8,250/T). It was found that the best fit of the burning velocity, the relative H atom concentration decay profile in the recombination region (measured by intensity of sodium chemiluminescence), and the temperature and composition profiles were obtained with feg /fe2 0 = 5 1 and fej 7 = (4.5 1.5) X 10, assuming equal efficiencies of all the molecules in the 

Another important feature of this analysis was that for fixed values of fei 7, and for the imposed condition of satisfactory prediction of measured burning velocities, the H atom concentration profiles in specific flames were not appreciably affected by the particular combination selected from the adjustable parameters concerned with reactions (viii), and (xviii)— (xxii), i.e. the rate coefficients g and ftj 9, and the ratios ftga/fegi ( a fesa)/ 2 0 21/ 20 and 2 2/ 20- This implies that, despite somewhat incomplete characterization at this stage, the flame and the computational approach may be used to study the reactions of its radical species with trace additives. Such an analysis with D2O, D2 and CO2 as the trace additives, has been used by Dixon-Lewis [172] to obtain information about the rate coefficients fe j d a. 1 2 3  

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