Combustion Kinetics Of The C4foundational Fuel Chemistry

The development of a combustion reaction kinetic mechanism that able to accurately predict the combustion property of fuels in a wide range is the premise of achieving clean and efficient energy utilization.And the core mechanism which is also referred to as the foundational fuel chemistry is an indispensable and important component of the combustion mechanism of practical fuels.Considering the development status of the core mechanism and the demand for the kinetic parameters at a wide temperature and pressure range,this work systematically studied the reaction kinetics of the C4 component of the core mechanism by theoretical methods.The potential energy surface of the isomeric butenyl radicals?C4H7?was calculated with high precision and the RRKM/master equation method was used to calculate the rate constant.Then the new calculation results were used for model development.The ignition delay time,laminar flame speed and the mole fractions of important intermediates are simulated by the updated model.Simulation results were further explained by rate of production?ROP?analysis and sensitivity analysis.The controlling kinetic mechanism of different skeleton structures on the combustion reactivity of butene isomers is summarized.In addition,the effect of pressure-dependent kinetics on the prediction ability of the model under different operating conditions is revealed based on the model comparison.The isomerization and dissociation mechanism of 1,3-butadiene and its isomers were studied.The main decomposition pathways of four C₄H₆ isomers were investigated by quantum chemistry calculation and kinetic theory.The experimental observation in previous studies on the initiation mechanism of 1,3-butadiene in pyrolysis and flame conditions were explored.The present study found that the "well-skipping" reaction that was missing in the core models is the reason for the contradictory observation of different experiments in describing the initial consumption pathway of 1,3-butadiene.The updated model can better explain and predict experimental phenomena over a wide temperature and pressure range.Then the kinetics of the resonance-stabilized C₄H₅ isomers-important C4 components of the core mechanism which have a large contribution to the formation of benzene was studied.The new photoionization cross section data were combined with previous photoionization mass spectrometry experiments to quantify the composition of the C₄H₅ isomers in hydrocarbon flames.At the same time,the isomerization and dissociation rate constants of C₄H₅ isomers were calculated by RRKM/master equation method and the kinetic simulation was conducted.The ratio of C₄H₅ isomers in hydrocarbon fuel flame was deduced from both experimental data and modeling results.The temperature-dependent rate constants of the reaction of 2-C₄H₅ and 12-C₄H₅ with acetylene were further calculated,and the contribution of the above-mentioned resonance-stabilized C₄H₅ isomer to the formation of benzene in the flame was revealed.Based on a typical potential energy surface of a C4 reaction system,the artificial neural network-high dimensional model representation method?ANN-HDMR?is used to explore the uncertainty propagation of input parameters in RRKM/main equation simulation process.The controlling factors that determine the uncertainty of rate constants and their branching ratio were revealed.Based on the above studies,the uncertainty of the combustion kinetic parameters of the C4 component was evaluated,and a C4 sub-mechanism containing temperature and pressure-dependent parameters with uncertain information was provided.