An ultraviolet laser absorption diagnostic for time-history in ethanol oxidation and model improvement ^?OH concentration

To provide micro-dimensional validation targets for chemical kinetic models of ethanol over a wide range of temperatures, pressures, and equivalence ratios, OH time-histories of highly Ar-diluted ethanol mixtures (equivalence ratios of 0.5 and 1.0) were measured in the temperature range of 1135-1759 K using a kinetic shock tube combined with UV absorption spectroscopy diagnostics. Diagnostic wavelengths of 306.6868 nm (1.5 atm) and 306.4676 nm (15 atm) were selected in the OH A -X(0,0) rovibronic band. Details on the temperature dependence of the OH profiles during ethanol oxidation were revealed by a series of temperature-increasing measurements of the primary shock tube temperature region, and the first measurements at 15 atm and below 1300 K offered additional validation targets for modern reaction models of ethanol. Four comprehensive reaction kinetic models of ethanol were evaluated against the measured OH time-histories. None of them perfectly aligns with all the experimental results reported in this study with Aramco 3.0 matching the closest. Therefore, kinetic analyses based on Aramco 3.0 were performed to identify key reactions governing the OH evolution behavior. A modified Aramco 3.0 was proposed by incorporating the recent experimental and theoretical work. These new quantitative measurements of OH time-histories in the oxidation of ethanol at 15 atm in particular provide a critical contribution to the database needed for model development and engine combustion organization.