# Construction of a Chemical Kinetic Mechanism of Five-Component Surrogate Fuel for RP-3 Kerosene
## 2 Development of Chemical Kinetic Mechanisms
Eventually, the complete low-temperature reaction route of 1,3,5-trimethylbenzene was determined as depicted in Figure 1. The number of species in the low-temperature reaction is 22, encompassing 69 elementary reactions. Based on the four single-component mechanisms, the NOx and PAH sub-mechanisms obtained previously, and the simplified mechanism of 1,3,5-trimethylbenzene constructed in this research, the mechanism of the five-component surrogate fuel mixture was developed. To ensure a superior prediction accuracy of the coupled mechanism in single-component parameter predictions, the construction of the coupled mechanism \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**NO.**} & \multirow{2}{*}{**Reactions**} & \multicolumn{4}{c}{**Kinetic Parameters**} \\ \cline{3-5}  & & **A** & **b** & **E\({}_{\text{a}}\) (J/mol)** \\ \hline
1 & C\({}_{7}\)H\({}_{8}\) + O\({}_{2}\) = C\({}_{6}\)H\({}_{5}\)CH\({}_{2}\) + HO\({}_{2}\) & 2.18 \(\times\) 10\({}^{7}\) & 2.5 & 47,300.0 \\
2 & C\({}_{7}\)H\({}_{8}\) + OH = C\({}_{6}\)H\({}_{5}\)CH\({}_{2}\) + H\({}_{2}\)O & 1.77 \(\times\) 10\({}^{5}\) & 2.4 & \(-\)602.0 \\
3 & C\({}_{6}\)H\({}_{5}\)CH\({}_{2}\) + O\({}_{2}\) = C\({}_{6}\)H\({}_{5}\)CHO + OH & 3.00 \(\times\) 10\({}^{15}\) & \(-\)1.6 & 47.0 \\
4 & C\({}_{6}\)H\({}_{5}\)CHO +OH = Al\({}^{-}\) + CO + H\({}_{2}\)O & 2.89 \(\times\) 10\({}^{8}\) & 1.3 & \(-\)1573.0 \\ \hline \hline \end{tabular}  
* A is referred to as the pre-exponential factor; b is the temperature index; E\({}_{\text{a}}\) represents the activation energy of the reaction.  
\end{table} 
Table 2: Partial elementary reactions of toluene. Figure 1: The main reaction paths of 1,3,5-trimethylbenzene. was based on the decoupling approach proposed by [PERSON] [29]. The C0-C1 core mechanism employed was derived from the individual component mechanisms selected in the previous section, with duplicate elementary reactions eliminated. The C2-C3 transition mechanism primarily originates from the simplified mechanism constructed by [PERSON] [39], which encompasses 10 species and 28 elementary reactions and exhibits strong applicability, having been utilized in numerous mechanism construction efforts [21; 25; 28]. The skeleton mechanism for C4 and above was derived from the large-molecule fuel mechanisms contained in each individual component mechanism. In the process of mechanism coupling, the following principles were adhered to: retain all macromolecular skeleton reactions above C4 for the five components, eliminate the duplicate reactions between C2 and C3, and merge the reactions of C0 to C1 molecules in the mechanisms of each single component. Figure 2 presents the flowchart for the construction of the five-component aviation kerosene fuel surrogate mechanism. The five-component surrogate fuel mixture mechanism encompasses 142 components and 496 elementary reactions. The thermodynamic and transport parameters of the mechanism were derived from the initial mechanisms of each single component, respectively. Figure 2: Construction process of five-component surrogate fuel coupling mechanism.