An experimental and computational investigation of methane/air partial oxidation.

摘要

An experimental and computational investigation of methane/air partial oxidation has been performed. A flow-reactor geometry was utilized in a three-tiered research effort to study the potential of utilizing this process as a hydrogen generation technology. This research established benchmark data, provided detailed characterization of the reaction zone, and linked experimental results to kinetic and system contributions. Specifically, experimental and computational results for equivalence ratios between three and five at operational pressures between eight and twenty atmospheres were examined.; Tier I of this research used a robustly designed flow reactor to examine the parametric space. Mass spectrometry measurements of exhaust product showed that hydrogen production is a function of pressure and equivalence ratio. Results from this study also characterized reactor functionality and indicated a significant production of particulate matter during operation. Spatial measurements of the reaction process were mapped via MS and temperature measurements. Results indicated a sharp reaction zone on the order of fifty centimeters in and temperatures well in excess of the adiabatic flame temperature.; Tier II used an optically accessible flow reactor to allow more detailed characterization of the reaction zone noted in the Phase I reactor. Characterization using laser induced fluorescence (LIF), dispersive infrared (IR) absorption of water and methane, tunable IR diode laser absorption of water, and measurement of reaction zone emission were performed on these mixtures. This study mapped LIF of ground state formaldehyde, absorption from methane and water, chemiluminescence of formaldehyde, and broadband emission in the soot deposition zone to determine temperature. These results were utilized for comparison to system modeling efforts.; Tier III was a computational modeling effort in which two kinetic mechanisms were used to link experimental observables to kinetic and system contributions. A model using a plug flow reactor with variable heat transfer along the length was constructed and analyzed using CanteraRTM. Modeling confirmed the strong dependence of formaldehyde and hydrogen peroxide in controlling the ignition process. Studies indicated that the necessary kinetic routes, pressure dependence, and key system parameters for these conditions are necessarily different than those controlling standard high temperature combustion.