## 2 Materials and Methods
### Experimental Setup
The main technical characteristics and measurement accuracies are shown in Table 3.  
The engine was warmed up to minimize the effects of exhaust emission variation during the engine cold-start. Before the substitution between fuels, the fuel tanks and injection systems were cleaned. After this, the engine was kept constant for 30 min with the new fuel. The fuel consumption was measured in triplicate to obtain an average value. The FTIR measurements were recorded for 20 min to ensure reliability, while the Testo values were an average of two readings. Later, the experimental uncertainty has been calculated and error bars have been included in all the figures. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Abbreviation** & \multicolumn{5}{c}{**\% Volumetric Make-Up**} \\ \hline \multicolumn{2}{c}{Diesel} & \multicolumn{5}{c}{100 diesel} \\ E15B35D50 & \multicolumn{5}{c}{15 ethanol + 35 biodiesel + 50 diesel} \\ E15B35 FTD50 & \multicolumn{5}{c}{15 ethanol + 35 biodiesel + 50 F-T diesel} \\ \hline
**Properties** & **Diesel** & **Ethanol** & **Biodiesel** & **F-Tiesel** & **E15B35D50** & **E15B35 FTD50** \\ \hline Chemical formula & C\({}_{14}\)H\({}_{26.1}\) & C\({}_{2}\)H\({}_{5}\)OH & C\({}_{19}\)H\({}_{35.3}\)O\({}_{2}\) & C\({}_{16.89}\)H\({}_{35.77}\) & C\({}_{14.13}\)H\({}_{26.88}\)O\({}_{1.21}\) & C\({}_{15.52}\)H\({}_{31.53}\)O\({}_{1.24}\) \\ Cetane number & 53.9 & 8 & 54.7 & 79 & 47.7 (a) & 59.6 \({}^{\text{a}}\) \\ Heat of vaporization [k]/kg] & 243 & 858 & 216 & 339 [37] & n/a & n/a \\ Lower heating value [MJ/kg] & 43.11 & 26.83 & 37.8 & 43.90 & 38.86 \({}^{\text{a}}\) & 39.13 \({}^{\text{a}}\) \\ Density at 15 \({}^{\circ}\)C [kg/m\({}^{3}\)] & 827.1 & 789.4 & 883.7 & 784.6 & 841.26 \({}^{\text{b}}\) & 820.01 \({}^{\text{b}}\) \\ Aromatics [wt \%] & 24.4 & 0 & -0 & 0.3 & n/a & n/a \\ Theoretical A-F ratio & 14.56: 1 & 10.33: 1 & 11.77: 1 & 14.91: 1 & 12.92: 1 & 13.20: 1 \\ C/H ratio & 6.41 & 3.97 & 6.43 & 5.67 & 6.02 & 5.65 \\ Carbon content [wt \%] & 86.47 & 52.14 & 77.15 & 84.91 & 78.06 & 77.28 \\ Hydrogen content [wt \%] & 13.53 & 13.13 & 12.03 & 15.09 & 12.94 & 13.72 \\ Oxygen content [wt \%] & 0 & 34.73 & 10.82 & 0 & 9.0 & 9.0 \\ \hline \hline n/a: not available \({}^{\text{a}}\) Estimated based on the mass fraction for each component [38]. \({}^{\text{b}}\) Estimated based on the volumetric fraction for each component [38]. & \multicolumn{1}{c}{} & & \\ \end{tabular}
\end{table} 
Table 2: Physical and chemical properties of the fuels. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Measure** & **Instrument** & **Range** & \multicolumn{2}{c}{**Accuracy of the**} \\  & & **Measurement Range** \\ \hline Exhaust gas (CO, CO\({}_{2}\), NOx\({}_{x}\), THC) & Multigas 2030 FTIR & 10 ppb-100\% full scale & \(\pm\)5\% \\ Exhaust gas (O\({}_{2}\)) & Testo 340 & 0–25\% & \(\pm\)0.2\% \\ Crank angle, engine speed & Digital shaft encoder & - & \(\pm\)1 rev/min \\ In-cylinder pressure & AVL GH13P pressure sensor & 0–250 bar & \(\pm\)1\% \\ Temperature & K-type thermocouples & of 0–1250 \({}^{\circ}\)C & \(\pm\)2.2 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Accuracy of the equipment used in this work.