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Show temperatures is poor. However, if the experimentally determined species concentration are used to infer a steady-state reactor temperature, considerably better agreement with the results computed using the quasiglobal model results. Note in particular that for the 87.5% toluene, 12.5% isooctane blend, Fig. 6, the measured temperatures show almost no variation with equivalence ratio. This anomalous behavior lends support to the rejection of the measured temperatures in favor of those inferred from concentration measurements, and in this can the agreement between quasiglobal model predictions and experiment is good. A major feature of the quasiglobal model outlined in this paper is the soot formation and gasification submodel included in the formulation. In developing this submodel, temperature and hydrocarbon concentrations were identified as controlling factors in soot formation, while temperature and oxygen concentration are controlling factors in the gasification process. Experimental evidence further indicates (Ref. 11) that aromatic hydrocarbons produce heavy soot concentrations under suitable conditions, while straight-chain aliphatic hydrocarbons do not. Therefore, the concentration of aromatic hydrocarbons has been used in the soot submodel to control the onset and amount of soot formation. Although the structure of acetylene, compared to other aliphatic hydrocarbons, favors the formation of polynuclear hydrocarbons through the fragmentation polymerization process, this route is nevertheless too slow to compare to the rate of soot formation by the condensation polymerization of aromatic hydrocarbons. Furthermore, the soot formation rates for specific precursors cannot yet be established. Therefore, in the quasiglobal formulation the aromatic hydrocarbon fraction is considered the only precursor responsible for soot emissions. Fig. 8 shows a comparison of predicted and measured soot concentrations for isooctane, toluene, and two toluene-isooctane blends. The experiments were carried out in a jet-stirred combustor, and the theoretical results were obtained with the well-stirred reactor computational model. The agreement is quite good. Experimentally, soot was not observed to be found in detectable amounts over the range of operating conditions that could be tested in the jet-stirred reactor when isooctane was used as the fuel. The soot submodel, as explained above, predicts no soot for isooctane combustion, since neither isooctane nor ethylene are used as a soot precursor. Fuel Characterization For SRC-II MP And No. 2 Fuel Oil Modeling of the combustion kinetics of an actual hydrocarbon fuel using the quasiglobal approach requires the characterization of the fuel in terms of aromatic and aliphatic components. This has been done for both No. 2 fuel oil and a 1.2.21 |