| The oxidation chemistry of methane and ethane has been studied in the intermediate temperature regime as a function of pressure using experiments and modeling. Species profiles were obtained for CH$sb4$, CO, CO$sb2$, C$sb2$H$sb6$, C$sb2$H$sb4$, C$sb2$H$sb4$O, CH$sb3$OH, C$sb3$H$sb6$, H$sb2$, CH$sb2$O, and CH$sb3$CHO in the High Pressure Optically Accessible Flow Reactor facility at pressures ranging from 3 to 10 atm, average reaction temperatures from 925 to 974 K, and equivalence ratios from 0.17 to 0.2. A laser induced fluorescence system was also developed to measure OH, however, complete concentration profiles could not be obtained.;To model the experimental data three kinetic mechanisms were tested. The first was developed for the methane section of the work and is an extension of an earlier high temperature mechanism from the literature. The second methane mechanism is from the Gas Research Institute (GRI). The last mechanism was developed to model the ethane results and is an extension of the previous GRI mechanism.;All three mechanisms were found to predict the methane results over a wide range of conditions. They reproduced the species profiles obtained in the flow reactor and also effectively predicted shock tube ignition delay and laminar flame speed data from the literature.;Results show the methane disappearance rate increases with increasing pressure, however; none of the models indicate any change in the reaction path. All three models predict that HO$sb2$ is the dominant radical for the destruction of CH$sb3$ and identify CH$sb2$O as a crucial intermediate. In addition, including the initially measured trace amounts of CH$sb2$O as an initial condition for the model calculations significantly reduced the predicted time to onset of methane disappearance.;For ethane oxidation only the final mechanism was used. It reproduced the flow reactor data reasonably well and effectively predicted ethane shock tube ignition delay and laminar flame speed data from the literature.;Results show that the ethane disappearance rate increases with increasing pressure and that six reactions are pressure dependent. It was found that HO$sb2$ chemistry is significant, controlling the formation of the aldehydes and ethylene oxide and providing a majority of the CH$sb3$ destruction. |
