Application to hydrogen oxidation in a flow system

Specifically, a stoichiometric reaction mixture was studied at a pressure of 20 Torr and a residence time of 8 s. Both isothermal and non-isothermal models were considered for a range of temperatures between 500 and 2311 K. The third body M is assumed to be made up from the molecular species H2, O2 and H2O with relative efficiencies of 1 0.4 6, respectively, for all third-body reactions [105]. Although the chemistry is derived from the original Dougherty and Rabitz scheme, the rate data were updated and, where possible, obtained from the CEC evaluation tables [26]. The sources for other reaction rate data are shown in Table 4.3. Oscillating ignition reactions constitute a particularly stringent test of mechanism 

Full reaction mechanism for hydrogen oxidation including rate data and sources 

The first stage of any reduction procedure should always be to establish which are the necessary species in the reaction mechanism over the range of conditions to be considered. In order to carry out the redundant species analysis, decisions must first be made about the important species and features which the reduced model must be able to reproduce accurately. In this example the important species were chosen as the primary reactants H2 and O2, and the product H2O. 

The analysis described in Section 4.6.1 was then applied over a range of ambient temperatures and reaction times for both the isothermal and non-isothermal model. Calculation of the 5, values revealed H2O2 and O3 to be redundant species for both models and at all reaction conditions tested. Table 4.4 shows examples of redundant species calculations from the full non-isothermal scheme at differing parts of the oscillatory trace 

Estimated effect of species for the rate of change of necessary species T = 2311 K, T = 818 K. A indicates species below the chosen threshold which are therefore redundant 

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