## 5 LBV of Key Hydrocarbon Components in Aviation Fuel
### LBV of Aromatic Hydrocarbons in Aviation Fuel  
In aviation fuel, aromatic hydrocarbons play a positive role in swelling, lubricity, thermal stability, etc. Table 7 summarizes LBV measurement information for various aromatics. [PERSON] et al. provided an earlier comparison of LBVs for benzene and its derivatives, concluding that benzene > ethylbenzene > n-propylbenzene > toluene > m-xylene [103]. Their study noted that when using the spherical flame method to measure LBV under fuel-rich conditions, flame-front instabilities can arise--an issue that also prevented [PERSON] et al. from assessing n-decane LBV under fuel-rich conditions at 1 atm [70]. [PERSON] et al. measured LBVs for numerous aromatics and observed that increased methylation generates more benzyl or benzyl-like groups, promoting radical chain termination and reducing LBV [104]. They also highlighted significant experiment-simulation discrepancies for aromatics. [PERSON] et al. investigated the LBVs of benzene, toluene, and ethylbenzene over 1-20 atm, finding that the LBV values consistently ranked (from smallest to largest) as toluene, ethylbenzene, and benzene [105]. [PERSON] et al. measured the LBVs for four butylbenzene isomers--arranged in ascending order as isobutylbenzene, n-butylbenzene, tert-butylbenzene, and sec-butylbenzene--and attributed differences to variations in the formation of methyl, cyclopentadienyl, and benzyl radicals, which strongly affect LBV at higher pressures and under fuel-rich conditions [106; 107]. [PERSON] et al. then measured the LBV of n-pentylbenzene and, together with other alkylbenzene data from the literature, analyzed the combustion mechanisms of alkylbenzene, concluding that methyl-, ethyl-, and propylbenzene decompose more readily at lower temperatures, while n-butyl- and n-pentylbenzene exhibit nearly identical decomposition temperature ranges [108]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Cycloalkane** & \multicolumn{3}{c}{**Experimental Conditions**} & & \\ \cline{2-5}  & **T (K)** & **P (atm)** & **LBV MeasurementMethods** & **Year** & **Ref.** \\ \hline Cyclopentane & 353, 403, 453 & 1, 2, 5 & Spherical flame method & 2018 & [98] \\ Cyclohexane & 353, 403, 453 & 1, 2, 5 & Spherical flame method & 2018 & [98] \\ Cyclohexane & 403 & 1, 5 & Spherical flame method & 2023 & [101] \\ Cyclohexane & 353 & 1 & Stagnation flame method & 2011 & [99] \\ Methylcyclohexane & 353 & 1 & Stagnation flame method & 2011 & [99] \\ n-Propylcyclohexane & 353 & 1 & Stagnation flame method & 2011 & [99] \\ n-Butylcyclohexane & 353 & 1 & Stagnation flame method & 2011 & [99] \\ n-Hexane & 353 & 1, 2, 5, 10, 20 & Spherical flame method & 2012 & [100] \\ Cyclohexane & 353 & 1, 2, 5, 10, 20 & Spherical flame method & 2012 & [100] \\ Methylcyclohexane & 353 & 1, 2, 5, 10, 20 & Spherical flame method & 2012 & [100] \\ Ethylcyclohexane & 353 & 1, 2, 5, 10, 20 & Spherical flame method & 2012 & [100] \\ Methylcyclohexane & 300–610 & 1 &
\begin{tabular}{c} Externally heated diverging \\ channel method \\ \end{tabular} & 2021 & [96] \\ Methylcyclohexane & 338 & 1 & Heat flux method & 2022 & [97] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Information on LBV testing for various cycloalkanes. Figure 10 compiles the maximum LBVs of benzene and its derivatives at 1 atm across various temperatures. As the temperature increases, the maximum LBV of benzene and its derivatives also increases. At approximately 353 K and 423 K, benzene and its derivatives follow similar LBV trends, with benzene and toluene exhibiting the largest and smallest LBVs, respectively. The LBVs of toluene, ethylbenzene, and propylbenzene display a \"decrease-increase-decrease\" pattern, matching the trends [PERSON] et al. reported at 304 kPa and 450 K [103].