Chemical Composition and Low-Temperature Fluidity Properties of Jet Fuels

Abstract

The physicochemical properties of petroleum-derived jet fuels mainly depend on their chemical composition, which can vary from sample to sample as a result of the diversity of the crude diet processed by the refinery. Jet fuels are exposed to very low temperatures both at altitude and on the ground in places subject to extreme climates and must be able to maintain their fluidity at these low temperatures otherwise the flow of fuel to turbine engines will be reduced or even stopped. In this work, an experimental evaluation of the effect of chemical composition on low-temperature fluidity properties of jet fuels (freezing point, crystallization onset temperature and viscosity at −20 °C) was carried out. Initially, a methodology based on gas chromatography coupled to mass spectrometry (GC–MS) was adapted to determine the composition of 70 samples of Jet A1 and Jet A fuels. This methodology allowed quantifying the content, in weight percentage, of five main families of hydrocarbons: paraffinic, naphthenic, aromatic, naphthalene derivatives, and tetralin- and indane-derived compounds. Fuel components were also grouped into 11 classes depending on structural characteristics and the number of carbon atoms in the compound. The latter compositional approach allowed obtaining more precise model regressions for predicting the composition–property dependence and identifying individual components or hydrocarbon classes contributing to increased or decreased property values.

Kinematic viscosity prediction of jet fuels and alternative blending components via comprehensive two‐dimensional gas chromatography, partial least squares, and Yeo‐Johnson transformation

“…Light C 9 and C 10 branched alkanes were identified as key molecules that decreased the viscosity of JP‐5/HRJ, JP‐8, Camelina, and F‐T‐based fuels. Even small additions of heavy C 15 and C 17 branched‐alkanes were the key group of molecules that increased the viscosity of ATJ, SIP, Camelina‐based fuels, and blending Jet‐A/HRJ mixtures [30]. Completing the saturated fraction, C 10 mono‐, and dicyclo‐alkanes induced contrasting effects with monocyclic molecules decreasing the viscosity of JP‐5/HDCJ, JP‐5/CHCJ, JP‐8, JP‐5, and Jet‐A and dicyclic structures increasing considerably the viscosity of JP‐5/HDCJ and JP‐10.…”

“…However, no further available information is provided in the report regarding the latent variables used for such prediction. Complementarily, Benavides et al, developed a linear regression model (R 2 = 0.91) using 22 latent variables to predict the kinematic viscosity at −20 • C of 70 Jet A/A-1 samples based on the semi-quantitation of alkanes, naphthenic, aromatic, naphthalenes, tetralin-and indane compounds via GC/MS [30]. Authors established that C 16 monobranched-alkanes and C 7 monobranched alkyl-benzenes strongly influenced the kinematic viscosity values of Jet A/A-1 [30].…”

“…Complementarily, Benavides et al., developed a linear regression model (R 2 = 0.91) using 22 latent variables to predict the kinematic viscosity at −20°C of 70 Jet A/A‐1 samples based on the semi‐quantitation of alkanes, naphthenic, aromatic, naphthalenes, tetralin‐ and indane compounds via GC/MS [30]. Authors established that C 16 monobranched‐alkanes and C 7 monobranched alkyl‐benzenes strongly influenced the kinematic viscosity values of Jet A/A‐1 [30]. More recently, Cain et al., showed the implementation of tile‐based variance ranking to improve PLS predictive modeling via GC×GC time‐of‐flight MS (GC × GC/TOF‐MS) [31].…”

Sustainable Aviation Fuels for Clean Skies: Exploring the Potential and Perspectives of Strained Hydrocarbons

“…Elevated freezing points and viscosity pose risks to engine performance and are closely monitored. The freezing point of aviation fuel is assessed using ASTM D2386-19, a standard method that identifies the temperature at which solid hydrocarbon crystals begin to form within the fuel …”

“…The freezing point of aviation fuels is significantly influenced by their chemical composition, with alkylated aromatics and carbon chain length being critical factors. ,, For instance, a blend comprising 43.2 wt % linear hydrocarbons, 6.3 wt % alkylated aromatics, and 28.1 wt % cycloalkanes demonstrated a remarkably low freezing point of −47 °C . Research by Robota et al highlighted the primary influence of the carbon chain length on the freezing point of synthetic aviation fuels.…”