# Construction of a Chemical Kinetic Mechanism of Five-Component Surrogate Fuel for RP-3 Kerosene
## 2 Development of Chemical Kinetic Mechanisms
The results show that, at the current ratio, the maximum error is the difference between the average molecular weight of the surrogate fuel and the target value, which is less than 5% and within an acceptable range. From the comparison of indicator parameters, the proposed RP-3 aviation kerosene surrogate fuel mixture model in this paper closely matches the data of actual fuel in various property indicators, reflecting the physical and chemical properties of RP-3 kerosene during combustion. n-Dodecane and n-tetradecane stand for linear alkanes. The number of carbon atoms in n-dodecane is close to that of aviation kerosene, and its physical properties are rather similar to those of aviation kerosene [28]. Thus, it is frequently selected as a surrogate fuel for simulating aviation kerosene. Likewise, n-tetradecane is a typical constituent in transportation fuels and can effectively represent the properties of heavy alkane substances in aviation kerosene [23]. This research selected the mechanism of n-dodecane and n-tetradecane constructed by [PERSON] [29]. The properties of isododecane are analogous to a 50% isohexadecane and 50% isooctane mixture. Compared to isooctane and isohexadecane, the average carbon number of isododecane is closer to that of the genuine kerosene fuel, thereby presenting an advantage in H/C. The mechanism employed is the simplified one constructed by [PERSON] [21]. Decalin has a six-membered double-ring structure and possesses unique advantages in terms of stability, combustion performance, and energy density. It has been proven to be one of the most thermally stable and heat-absorbing fuels in aviation fuels and is often selected as a surrogate component for cycloalkanes in transportation fuels [30]. The mechanism was chosen from [PERSON]'s research [31]. In this research, 1,3,5-trimethylbenzene was chosen to represent the aromatic group as a candidate component for surrogate fuels, and the detailed mechanism constructed by [PERSON] [32] was selected. The sub-mechanisms of NOx and PAHs were simplified from the detailed mechanism proposed by [PERSON] [33;34] and refined by [PERSON] [35;36]. The final PAH mechanism comprised 20 species and 139 elementary reactions. Since the previously selected 1,3,5-trimethylbenzene (C\({}_{9}\)H\({}_{12}\)) mechanism was the detailed one constructed by [PERSON] [32], which encompasses 450 species and 2569 elementary reactions, it was required to analyze and simplify the detailed mechanism of 1,3,5-trimethylbenzene. Among multiple components, the small-molecule reactions in various components all undergo the same C0-C3 mechanism, and the oxidation path of \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Item** & **Octane Number** & **H/C** & \begin{tabular}{c} **Lower Heating Value** \\ **(M/L)** \\ \end{tabular} & \
\begin{tabular}{c} **Molecular** \\ **Weight** \\ \end{tabular} &
\begin{tabular}{c} **Density** \\ **(20 °C) (g/cm\({}^{2}\))** \\ \end{tabular} & **Smoke Point** \\ \hline RP-3 [27] & 43.3 & 1.963 & 42.8 & 150 & 0.778 & 20 \\ Simulation & 43.278 & 1.9608 & 43.48 & 157.02 & 0.787 & 20.177 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Selected indicator values of RP-3 aviation kerosene and five-component surrogate fuels. benzene, the oxidation product of 1,3,5-trimethylbenzene, is consistent with the decalin mechanism constructed by [PERSON] [31]. Hence, the approach employed was the ROP analysis method, which analyzes the oxidation of 1,3,5-trimethylbenzene to generate C3 small molecules and products containing benzene rings, and the subsequent reactions were incorporated into the multi-component mechanism. After obtaining the low-temperature oxidation route of 1,3,5-trimethylbenzene, the detailed mechanism was simplified. Considering that the oxidation route from toluene to benzene was not included in the coupling mechanism, the reaction route from toluene to benzene constructed by [PERSON] [37] was utilized, as presented in Table 2. This mechanism contains only four elementary reactions and exhibits strong applicability [38].