Time-resolved CO2 concentration and ignition delay time measurements in the combustion processes of n-butane/hydrogen mixtures

In order to research kinetics properties of hydrogen-enriched n-butane mixtures, this study measured the ignition delay time of nC(4)H(10)/H-2 mixtures in shock tube tests and time-resolved CO2 concentrations during combustion process by combining laser absorption diagnostics. The experimental data were compared with numerical predictions from three kinetic mechanisms, and the modified NUIG Mech shows improved performances in predicting ignition delay time and time-resolved CO2 concentrations. Higher nC(4)H(10):H-2 ratio led to lower reactivities because the main combustion happens after the oxidation of nC(4)H(10). Lean mixtures (phi=0.5) ignites significantly faster than stoichiometric mixtures. It is possible to adjust ratios of nC(4)H(10) to H-2 in fuel mixture to fit the combustor design because of the varying combustion characteristics. The CO2 formation occurs after complete oxidation of nC(4)H(10) with the primary sources being small molecules or radicals. Reaction path analyses show that nearly half of the CO2 is formed through the reaction CO + OH = CO2 + H. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.