The combustion chemistry of simple alcohol fuels

The detailed chemistry of simple alcohol fuels is investigated through a combination of experimental and computational techniques. The Princeton atmospheric pressure flow reactor is used to obtain profiles of temperature and stable species concentrations in the oxidation of methanol, ethanol, normal- and iso-propanol, tert-butyl alcohol (TBA), and methyl tert-butyl ether (MTBE) at initial temperatures of 980-1120 K. The methanol and ethanol data exhibit a kinetic deceleration (or "plateau") in the temperature and species profiles that has not been observed previously. Methanol has the unique property that nearly half of its heat release occurs before the CO peak.;Detailed kinetic modeling is used to derive reaction mechanisms for methanol oxidation, methanol pyrolysis and ethanol oxidation. The plateau phenomenon in methanol and ethanol oxidation is associated with decreasing chain branching during fuel decay. The H + O;A general mechanism for alcohol fuel oxidation is developed, based on the experimental results. All alcohols produce both oxygenated and non-oxygenated hydrocarbon intermediates, but the ratio depends on the molecular structure of the fuel. Primary alcohols are more susceptible to dehydrogenation than to dehydration. The direct production of aldehydes from primary alcohols causes these fuels to have much shorter reaction times than do the corresponding alkanes. By contrast, tertiary alcohols are highly susceptible to unimolecular dehydration and have chemistry which closely resembles that of non-oxygenated hydrocarbons. Secondary alcohols react both by dehydration to alkenes and by dehydrogenation to ketones. MTBE decomposes directly to methanol and isobutene.