Multiscale Combustion Kinetics of n-Tetradecane: Integrating Reactive Dynamics with Kinetic Modeling.

Abstract

Uncovering the inherent nature of fuel combustion depends on a detailed and accurate combustion reaction mechanism. This research examines the combustion characteristics of n-tetradecane, which is a crucial component of transportation fuels. Employing advanced quantum chemical techniques, potential energy surfaces and computed rate constants for H atom abstraction by Ḣ/Ȯ(³P)/ȮH/HȮ₂/ĊH₃ radicals at the DLPNO-CCSD(T)/CBS(T-Q)//M06-2X/def2-TZVP level were outlined. The high-pressure limit rate constants, determined across the temperature range of 500-2000 K, unveiled intricate details in secondary carbon atom reactions, highlighting the critical influence of torsional anharmonicity on reaction kinetics. The study further highlighted the necessity of considering both entropy and enthalpy for precisely predicting the thermochemical properties. By integration of our insights with the ReaxGen program, a comprehensive kinetic model for n-tetradecane combustion was developed. This model not only predicts ignition delay times under a wide variety of conditions but also effectively captures negative temperature coefficient behavior. It outperforms existing models in predicting key species concentrations during combustion, providing valuable insights into intermediate species formation. Systematic sensitivity analysis and flux analyses revealed that H atom abstraction reactions mediated by Ḣ/Ȯ(³P)/ȮH/HȮ₂ critically control the reaction kinetics. This model is a fundamental building block for demystifying the combustion dynamics of alternative fuels and promoting the evolution of more efficient and environmentally friendly combustion technologies.