## 3 Results and Discussion
### Emissions Characteristics
#### 3.2.3 Toxic Aromatic VOCs, BTEX
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{2}{c}{**PD0**} & \multicolumn{2}{c}{**PD10**} & \multicolumn{2}{c}{**PD30**} & \multicolumn{2}{c}{**PD100**} \\ \hline
**Name** & **Formula** & **Name** & **Formula** & **Name** & **Formula** & **Name** & **Formula** \\ \hline Ethyl alcohol & C\({}_{2}\)H\({}_{0}\)O & Ethyl alcohol & C\({}_{2}\)H\({}_{0}\)O & Ethyl alcohol & C\({}_{2}\)H\({}_{0}\)O & Trans-2-Butene & C\({}_{4}\)H\({}_{8}\) \\ Tetrahydrofuran & C\({}_{4}\)H\({}_{8}\)O & Tetrahydrofuran & C\({}_{4}\)H\({}_{8}\)O & Tetrahydrofuran & C\({}_{4}\)H\({}_{8}\)O & Ethyl alcohol & C\({}_{2}\)H\({}_{0}\)O \\ Benzene & C\({}_{6}\)H\({}_{6}\) & Benzene & C\({}_{6}\)H\({}_{6}\) & Benzene & C\({}_{6}\)H\({}_{6}\) & Tetrahydrofuran & C\({}_{4}\)H\({}_{8}\)O \\ Toluene & C\({}_{7}\)H\({}_{8}\) & Toluene & C\({}_{7}\)H\({}_{8}\) & Toluene & C\({}_{7}\)H\({}_{8}\) & Benzene & C\({}_{6}\)H\({}_{6}\) \\ Ethhylbenzene & C\({}_{8}\)H\({}_{10}\) & Ethylbenzene & C\({}_{6}\)H\({}_{10}\) & Octane & C\({}_{6}\)H\({}_{18}\) & Toluene & C\({}_{7}\)H\({}_{8}\) \\ m,p-Xylene & C\({}_{8}\)H\({}_{10}\) & m,p-Xylene & C\({}_{8}\)H\({}_{10}\) & Ethylbenzene & C\({}_{8}\)H\({}_{10}\) & Octane & C\({}_{6}\)H\({}_{18}\) \\ Nonane & C\({}_{6}\)H\({}_{20}\) & Nonane & C\({}_{6}\)H\({}_{10}\) & m,p-Xylene & C\({}_{8}\)H\({}_{10}\) & Ethylbenzene & C\({}_{8}\)H\({}_{10}\) \\ o-Xylene & C\({}_{8}\)H\({}_{10}\) & o-Xylene & C\({}_{8}\)H\({}_{10}\) & o-Xylene & C\({}_{8}\)H\({}_{10}\) & m,p-Xylene & C\({}_{8}\)H\({}_{10}\) \\ Decane & C\({}_{10}\)H\({}_{22}\) & Decane & C\({}_{10}\)H\({}_{22}\) & Decane & C\({}_{10}\)H\({}_{22}\) & o-Xylene & C\({}_{8}\)H\({}_{10}\) \\ Tetradecane & C\({}_{14}\)H\({}_{30}\) & Tetradecane & C\({}_{14}\)H\({}_{30}\) & Tetradecane & C\({}_{14}\)H\({}_{30}\) & Decane & C\({}_{10}\)H\({}_{22}\) \\  & & & & & 2-Ethyl-1-hexanol & C\({}_{8}\)H\({}_{18}\)O \\  & & & & & Tetradecane & C\({}_{14}\)H\({}_{30}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 9: List of VOCs observed under an engine load of 40 Nm. In this study, benzene tended to increase with an increased blend rate of palm oil biodiesel regardless of engine load. However, the emission trends of toluene, ethylbenzene, and xylene varied depending on engine load. Dealkylation of aromatics in the fuel-rich area increased benzene. [PERSON] et al. [34] reported that the main causes of BTEX emissions from an engine are pyrosynthesis occurring during combustion in the cylinder and structural modification, while [PERSON] et al. [69] reported benzene was generated by unburned fuel under different combustion conditions in a fuel-rich state. [PERSON] et al. [70] also reported an increase in benzene due to the poor atomization of biodiesel and a decrease in toluene and xylene due to the low aromatic content of biodiesel. At an engine load 40 Nm, Benzene except PD100 increased with an increasing blend ratio of palm oil biodiesel. Further, Toluene, Ethylbenzene, and xylene of blended fuels were lower than those of pure diesel and increased with an increasing blend ratio of palm oil biodiesel. At this condition, the fuel consumption was more than doubled, as shown in Figure 3. This means that the amount of injected fuel will be more than double. Under idle conditions, the amount of air intake was the same at all engine loads, so under an engine load of 40 Nm, more fuel-rich areas occurred in the combustion chamber due to the increased fuel injection of high viscosity palm oil biodiesel. Thus, more benzene is produced than at an engine load of 0 Nm. The generation of toluene, ethylbenzene, and xylene increased under these conditions. The emission rate of benzene was drastically reduced for PD100 with an engine load of 40 Nm. This was likely the result of rapid oxidation of benzene due to the rapid combustion reaction that occurs during the combustion of the main injection.