Pyrolysis study and surrogate fuel construction of real RP-3 aviation kerosene with SVUV-photoionization molecular-beam mass spectrometry

Abstract

The pyrolysis of real RP-3 aviation kerosene was studied experimentally in a jet-stirred reactor using synchrotron photoionization and molecular beam mass spectrometry in the range of 700–1050 K. The initial chemical constituents of the RP-3 aviation kerosene were meticulously identified through molecular beam mass spectrometry and gas chromatography. The compositional analysis divided the sample into three principal hydrocarbon groups: long-chain alkanes constituted the predominant fraction at 63.2 %, followed by cycloalkanes at 18.8 %, and aromatic hydrocarbons at 17.2 %. A three-component surrogate fuel was chosen to simulate the pyrolysis characteristics of RP-3 aviation kerosene, comprising 66.2 % n-dodecane (NC₁₂H₂₆), 18.0 % 1,3,5-trimethylcyclohexane (T135MCH), and 15.8 % n-propylbenzene (NPB). A comprehensive kinetic model for the surrogate fuel, involving 462 species and 3199 reactions was developed and validated against experimental data obtained from the pyrolysis of real RP-3 aviation kerosene. Furthermore, the pyrolysis process of the RP-3 was elucidated through a detailed analysis of the production rates of the initial components in the surrogate fuel, which can be classified into three primary reaction pathways. Alkane components undergo alkyl radical chain propagation processes, resulting in the formation of various alkenes. Aromatic components primarily convert into benzene and toluene, while only a small fraction undergoes benzene ring addition reactions to form polycyclic aromatic hydrocarbons (PAHs). Cycloalkanes mainly decompose via unimolecular pathways, generating alkenes, while a smaller proportion undergoes multiple H-abstraction reactions, ultimately transforming into aromatic compounds. Sensitivity analysis indicates that consumption of the fuel components is promoted by H/CH₃ radicals at low temperatures. As the temperature rises to 880 K, the insufficient supply of these radicals leads to a competing reaction between the fuel components and the pyrolysis products. The results of the study could contribute to analytical methods for complex mixture fuels and facilitate a comprehensive exploration of jet fuels under combustion conditions.