## 3 Results and Discussions
### Energy Analysis  
To evaluate the effects of the fuel type on the energetic performance of the engine, the inlet and outlet energy fractions (work energy flow rate, exhaust gases energy flow rate, and energy losses flow rate) were calculated by dividing each energy component by the energy of the fuel, as shown in Table 4. During the tests, the IMEP was kept constant whereas the fuel flow variated. The rate of energy inlet from the fuel is mainly related to the LHV and the combustion efficiency of the fuel. The inlet fuel energy increased when the engine was fueled with the E15B35 FTD50 blend compared with diesel. In order to maintain the same IMEP, when the engine was fueled with different fuels, more fuel was consumed for E15B35 FTD50 (10.8% in mass) mainly due to the lower LHV (9.8%) of the blend in comparison with diesel fuel, as shown in Table 2. As for the E15B35D50 blend, the mass fuel consumption was increased by 11.8% and the LHV decreased by 8.7% when compared with diesel. In comparison with the E15B35D50 blend, the blend of ethanol and F-T diesel (E15B35 FTD50) presented a slight difference in the LHV value of approximately 1%. Previous researchers had reported similar results and found an increase in the fuel energy rate whilst the energy efficiency decreased [27; 66], because of the difference in the LHV of the tested fuels compared to the baseline diesel. The small variation in the energy outlet rate by exhaust gases for the evaluated fuels could be explained due to the differences in the engine-outlet exhaust gas temperature and emissions. The measured exhaust gas temperature ranged around 234-240 \({}^{\circ}\)C for diesel, 230-234 \({}^{\circ}\)C for E15B35D50, and 232-235 \({}^{\circ}\)C for E15B35 FTD50. The addition of ethanol to F-T diesel and biodiesel (E15B35 FTD50) caused a decrease in the exhaust temperature of the engine probably due to the alcohol cooling effect related to the higher heat of evaporation. Previous works have reported similar results of combustion temperature decrease by adding ethanol to diesel or biodiesel [67]. In addition, as the exhaust energy is directly \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Fuel** & **Fuel Energy Rate (kW)** & **Work Rate (kW)** & **Exhaust Gas Energy Rate (kW)** & **Heat Losses Rate (kW)** \\ \hline Diesel & 4.70 & 1.25 & 1.58 & 1.87 \\ E15B35D50 & 4.74 & 1.25 & 1.45 & 2.04 \\ E15B35 FTD50 & 4.75 & 1.25 & 1.59 & 1.92 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Energy distribution in the engine control volume. related to the engine output emissions, the slightly higher emissions for E15B35 FTD50 of some measured species have influenced the exhaust energy rate. Although, for the blend E15B35D50 the exhaust energy rate of the blend was mainly affected by the lower CO2 amount in the exhaust and presented the lowest value among the tested fuels. Nevertheless, the released amount of energy rate in the exhaust might be partially recovered and thus enhance the energy efficiency [68]. Moreover, other losses such as the heat transfers from the cylinder walls and by the coolant were merged to simplify the control volume. Figure 5 shows the energy balance of diesel, E15B35D50, and E15B35 FTD50. The graph shows that 26.6% of the inlet fuel energy of diesel fuel was converted to outlet engine work, 33.6% was discharged in the exhaust gases, whereas the remaining (39.8%) was computed as energy losses. Similarly, for the combustion of E15B35 FTD50, the energy distribution has revealed that 26.2% of the inlet energy was transformed into outlet work, 33.4% was lost through exhaust gases, and it can be deduced that 40.3% of the inlet energy is lost through heat transfer. Similar results were reported by previous works [69; 70]. [PERSON] et al. [27] found that the mixture of butanol (5-20% \(v/v\)), biodiesel (20% \(v/v\)), and diesel (60-75% \(v/v\)) resulted in lower outlet work energy and energy efficiency than when using diesel fuel.