Ethanol pyrolysis kinetics using H2O time history measurements behind reflected shock waves

Abstract

Abstract The thermal decomposition of ethanol has been studied under pyrolytic conditions behind reflected shock waves in the 1250 to 1677 K temperature range, at an average pressure of 1.31 atm for a mixture highly diluted in Ar. A laser absorption technique was utilized to measure H2O time-histories, and the detailed kinetics mechanism (AramcoMech2.0) was selected among various models from the literature based on its a priori agreement with the experimental data in the present study. Sensitivity and rate-of-production analyses were performed and showed that the C2H5OH→C2H4+ H2O (R1) decomposition pathway is almost the sole reaction contributing to H2O formation at the early times under the present conditions, allowing an a priori direct measurement of its rate coefficient k1. The rate coefficient was determined to be defined as the Arrhenius equation k1 (s−1) = 3.37 × 1011 exp (–27174 K/T), which is in very good agreement with Kiecherer et al. (2015), where k1 was also directly determined under similar conditions. Secondary chemical reactions taking place in the thermal decomposition have very low influence in the H2O formation during the time-frame selected, leading to an uncertainty for k1 of approximately 20%. The full H2O time histories are useful for validating the full ethanol kinetics mechanism for future validation.