## 4 Results and Discussion
### Experimental Results  
Figure 5 presents the change in brake specific fuel consumption (BSFC) at various engine loads. The general trend of this parameter decreases with an increasing load of diesel engine for all samples of the tested fuel; this behavior ensured a perfect combustion. \begin{table}
\begin{tabular}{l l} \hline \hline
**Parameter** & **Value** \\ \hline Cylinder head, Manifold & Stationary \\ Cylinder wall, Valve rod & Unspecified \\ Piston, Valve bottom & Specified \\ Cartesian Velocity & 0.001 m/s \\ Static Pressure & 0.081 MPa \\ Air inlet Temperature & 300 K \\ K-\(\epsilon\) value Model & 0.001 m\({}^{2}\)/s \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The applied boundary conditions. For all operating conditions, the fuel blends at D80B20, D80B20N50, D80B20N100, and D80B20N150 achieved higher fuel consumption than pure diesel D100. The increase in fuel consumption can be described as a natural result of developments in the physical properties of the fuel, such as an increase in viscosity and density and a decrease in calorific value, which in turn caused an increase in the amount of fuel charge injected into the combustion chamber when compared to the operating conditions of pure diesel D100. The current data are in agreement with the data collected by several researchers [26; 27]. Brake thermal efficiency (BTE) is the main criterion for determining engine performance. Figure 6 explains the change in BTE for the fuel samples resulting from experiments, D100, D80B20, D80B20N50, D80B20N100, and D80B20N150, at varying loading conditions. The break thermal efficiency of all fuel blend samples increases with the load to up to an approximately 90% loading condition near full load and then begins to decrease. Near full loading conditions, the results for BTE show that the mixture of Al\({}_{2}\)O\({}_{3}\) nanoparticles gave the lowest values compared to the rest of the other samples, especially D80B20N150, and this is due to the decrease in the volumetric heating of the mixture, which causes a decrease in brake thermal efficiency. [PERSON] et al. [25] reported that increasing the density and viscosity caused uneven combustion, so that is a reason for reducing brake power. Figure 5: Variation of the BSFC with load for all fuel blend samples: D100, D80B20, D80B20N50, D80B20N100, and D80B20N150. Figure 6: Variation of the BTE with the load for all fuel blend samples: D100, D80B20, D80B20N50, D80B20N100, and D80B20N150. Figure 7 displays the carbon monoxide CO emissions of samples D100, D80B20, D80B20N50, D80B20N100, and D80B20N150 at various engine loads. Compared to all blend samples with pure fuel, in low pregnancy due to the abundance of oxygen molecules, nanoparticles help increase the surface area (the addition of nanoparticles causes their higher surface area ratio, exhibiting strong thermal, oxidative, and catalytic activity, which can facilitate the evaporation and diffusion of the reaction). So, the incorporation of these nanoparticles can improve the burn fuel, which can then easily convert CO to CO\({}_{2}\) and reduce CO emissions, and this result is consistent with this [22; 23]. While the data of CO emissions show increases in the engine load because CO emissions are extremely dependent on the fuel/air ratio, generally, the results revealed that CO emissions are the lowest in biodiesel blends, followed by D80B20N50, D80B20N100, and D80B20N150, with lower values in all cases of the loading conditions. So, the lower CO emissions for D80B20N50, D80B20N100, and D80B20N150 fuel blends may be attributed to the added oxygen fraction in the fuel blend, thereby proving the possibility combustion of the fuel [24]. Figure 8 shows that the increase in CO\({}_{2}\) emissions is very clear with the increase in the engine loads with all fuel sample blends. So, the CO\({}_{2}\) emissions percentage was 77% at the D80B20N150 concentration, in conditions of 1800 rpm and near full load, compared to pure diesel fuel, where it was 66%.