This program (an extension of a current NSF program) is directed to the study of effects of pressure on hydrocarbon oxidation in low and intermediate (550-1000K) temperature regimes, with acquisition of kinetic information at pressures up to 20 atmospheres for oxidation of pure hydrocarbons containing four or more carbon atoms. A major part of the work will utilize a recently-developed pressurized flow reactor test facility. The experiments to be conducted will provide resolution of mechanistic details (and the effects of pressure on these) associated with alkylperoxy radical reactions and definition of the role of diperoxy radicals as branching agents. Other separate complementary bench-scale experiments will also be utilized to elucidate mechanistic details controlling the oxidation of straight and branched hydrocarbons in the low and intermediate temperature regimes. Gas chromatography, GC/MS, and GC/FTIR diagnostics will be used for chemical analysis of stable reaction intermediates and products, while in-situ measurements of stable and radical species will be carried out using FTIR spectroscopy. Specific objectives are: (1) Obtain kinetic information for oxidation of pure hydrocarbons between 550 and 1000K at pressures up to 20 atmospheres; (2) Determine effects of pressure on oxidation mechanism(s) in each temperature regime and how pressure affects boundaries separating the regimes; and, (3) Suggest and refine mechanisms for modeling the alkylperoxy radical reaction system and the diperoxy radical reaction system. Hydrocarbon oxidation chemistry at low to intermediate temperatures (below 1000K) plays a significant role in operation of many combustion devices, notably internal combustion engines, in some cases accounting for a significant fraction of the overall heat release as well as strongly affecting input boundary conditions for the higher temperature regions in these devices. Since such devices operate at elevated pressures, fundamental research on low and intermediate temperature hydrocarbon oxidation at pressures well above atmospheric is important to furthering the understanding of many practical internal combustion engine phenomena, including engine knock, preignition fuel decomposition, pollutant formation, and general autoignition processes.
