| In recent years, because of concern associated with air pollution and conventional transportation fuel replacement, an interest in ethanol as a fuel extender, octane enhancer, and oxygen-additive in, or as an alternative fuel to reformulated gasoline has increased significantly. To gain a fundamental understanding of its combustion chemistry, the pyrolysis and oxidation of ethanol was experimentally and numerically studied and a comprehensive kinetics mechanism for ethanol combustion was developed in this thesis.;The rate constant of the dominant ethanol decomposition reaction, C 2H5OH = C2H4 + H2O, was determined by flow reactor pyrolysis experiments in the presence of radical trappers at 1.7--3.0 atm and 1045--1080 K. The multi-channel unimolecular decomposition of ethanol was also investigated using RRKM/master equation approach. The effects of the hindered rotations in C2H5OH and quantum tunneling on the H2O elimination reaction were taken into account. The calculated rate constant for the dominant decomposition reaction is in excellent agreement with the recent theoretical work of Tsang (2001) as well as with the experimental measurements of Herzler et al. (1997) and the present data.;A detailed mechanism for ethanol combustion was developed in a hierarchical manner, beginning with the H2/O2 reaction mechanism, and subsequently constructed by encompassing C1/O2, C2HX/O2 (X = 1--6), CH 3CHO/O2, and C2H5OH/O2 subsets in order of increasing complexity. At each level, the newly added portions of the mechanism were tested and validated by thorough comparison between numerically predicted and experimentally observed results found in laminar premixed flames, shock tubes, and flow reactors. In conjunction with sensitivity and reaction flux analyses, important updates/modifications to the original mechanisms (H2/O2 mechanism of Mueller et al. (1999a), CH3OH/O2 mechanism of Held and Dryer (1998), and C 2H5OH/O2 mechanism of Marinov (1999)) were made to reflect recent publications of thermodynamic data, rate coefficients, and channel results. The present ethanol mechanism predicts reasonably well the major species profiles observed in the VPFR experiments, and improves agreement with the experimental targets originally investigated by Marinov (1999). The present mechanism also has excellent predictive capabilities for the H 2/O2, CO/O2, CH2O/O2, and CH3OH/O2 systems.;Ethanol pyrolysis and oxidation experiments were conducted in a variable pressure flow reactor (VPFR) at 3.0--12.0 atm and 800--978 K. Profiles of stable species concentrations were measured using a Fourier Transform Infrared spectrometry combined with on-line analyzers for O2, CO, and CO 2. These experiments provide detailed kinetics information for the development and validation of ethanol mechanisms. In the case of ethanol pyrolysis work, an alternative comparison approach of model predictions with flow reactor experiments was developed because for these pyrolysis cases the non-idealities in the VPFR mixing region resulted in memory effects on the chemical kinetics thereafter. |
