Showing papers in "International Journal of Chemical Kinetics in 2021"

A detailed chemical kinetic modeling and experimental investigation of the low‐ and high‐temperature chemistry of n‐butylcyclohexane

Abstract: The work at LLNL was supported by the U.S. Department of Energy, Vehicle Technologies Office (program managers Mike Weismiller and Gurpreet Singh) and performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. NUIG acknowledges the financial support of Saudi Aramco, the Irish Research Council and Science Foundation Ireland under grant numbers 15/IA/3177 and 16/SP/3829. Jinhu Liang acknowledges the International Scientific Cooperation Projects of Key R＆D Programs in Shanxi Province via project number 201803D421101.

Homogeneous conversion of NOx and NH3 with CH4, CO, and C2H4 at the diluted conditions of exhaust‐gases of lean operated natural gas engines

Abstract: Understanding gas‐phase reactions in model gas mixtures approximating pre‐turbine heavy‐duty natural gas engine exhaust compositions containing NO, NH$_{3}$, NO$_{2}$, CH$_{4}$, CO, and C$_{2}$H$_{4}$ is extremely relevant for aftertreatment procedure and catalyst design and is thus addressed in this work. In a plug‐flow reactor at atmospheric pressure, five different model gas mixtures were investigated in the temperature range of 700‐1 200 K, using species analysis with electron ionization molecular‐beam mass spectrometry. The mixtures were designed to reveal influences of individual components by adding NO$_{2}$, CH$_{4}$, CO, and C$_{2}$H$_{4}$ sequentially to a highly argon‐diluted NO/NH$_{3}$ base mixture. Effects of all components on the reactivity for NO$_{x}$ conversion were investigated both experimentally as well as by comparison with three selected kinetic models. Main results show a significantly increased reactivity upon NO$_{2}$ and hydrocarbon addition with lowered NO conversion temperatures by up to 200 K. Methane was seen to be of dominant influence in the carbon‐containing mixtures regarding interactions between the carbon and nitrogen chemistry as well as formaldehyde formation. The three tested mechanisms were capable to overall represent the reaction behavior satisfactorily. On this basis, it can be stated that significant gas‐phase reactivity was observed among typical constituents of pre‐turbine natural gas engine exhaust at moderate temperature.

An experimental and kinetic modeling study of the ignition delay and heat release characteristics of a five component gasoline surrogate and its blends with iso-butanol within a rapid compression machine

Abstract: This study investigates the performance of a five component gasoline surrogate (iso-octane, toluene, n-heptane, 1-hexene, and ethanol) in representing the ignition delay time (IDT) behavior of gasoline (reference gasoline PR5801—research octane number 95.4, motor octane number 86.6), at conditions of 675–870 K, 20 bar, and Ф = 1 (stoichiometric) within a rapid compression machine (RCM). Experimentally, the surrogate produces a good representation of the ignition behavior of the gasoline at these conditions, displaying a similar IDT profile. The influence of blending with iso-butanol on the surrogate's ignition delay behavior is also investigated, at blends from 5% to 70% of iso-butanol by volume. The surrogate continues to produce a reasonable representation of the experimental IDTs of gasoline and iso-butanol blends, except under a high degree of iso-butanol blending (50% iso-butanol), where the surrogate produced longer IDTs, particularly at temperatures below 740 K. Blends of 5% and 10% iso-butanol produce IDTs shorter than that of any other blend, including the “neat” surrogate, at temperatures of 740–770 and 830 K, respectively. Kinetic modeling of RCM IDTs is performed using CHEMKIN-PRO (Reaction Design: San Diego, CA, 2011) and a combined mechanism of the Sarathy et al. butanol isomers mechanism (Progress in Energy and Combustion Science 2014; 44: 40–102) and Lawrence Livermore National Laboratories “Gasoline Surrogate” mechanism (Proceedings of the Combustion Institute 2011; 33(1): 193–200). The model produces good IDT predictions below 740 K but overpredicts reactivity in the negative temperature coefficient region. Heat release rate analysis is conducted for experimental and modeling results to investigate low-temperature heat release (LTHR) behavior. Simulations largely fail to accurately reproduce this behavior. This analysis, combined with local OH and brute force Δhf sensitivity analyses, indicates the significance of LTHR in the determination of IDTs and provides RCM heat release rates for future model validation.