## 5 Conclusions  
Experimental and CFD analysis was carried out for the combustion of neat diesel and biodiesel blends with Al\({}_{2}\)O\({}_{3}\) nanoparticles for diesel engines. Investigations were included for five samples of diesel and additives. The following are the major conclusions that can be drawn from the study's findings:  
* The BSFC values for nanomaterials blended fuels were higher compared to that of D100 due to their lower heating value and higher density. Among all blended fuels, the D80B20N150 blended fuel showed the highest average BSFC, followed by the rest of the nanomaterial fuel samples blends.
* The performance parameters display that the brake thermal efficiency with biodiesel increased compared to pure diesel fuel due to the change in density, viscosity, and calorific value, while this behavior differs with the blending of nanomaterials (it decreases). The lowest brake efficiency compared to pure diesel fuel was specified at D80B20N150, followed by the rest of the nanomaterial fuel sample blends. The numerical results of BTE showed consistency with this behavior.
* Through emissions investigations, CO and HC emissions have been recorded to be lower using nano-blended fuel compared to pure diesel fuel. The results indicated that CO and HC emissions for fuel mixed with the nanoparticles D80B20N150 recorded the highest average decrease, followed by the rest of the nanomaterial fuel samples.
* By investigating NOx emissions, the results indicated a noticeable increase for the D80B20 blended fuel compared to the pure diesel fuel. This indicates that biofuel provides a higher percentage of oxygen during the combustion procedure, while a reduction in NOx emissions appeared with nanomaterials blends. Also, the numerical results supported this behavior, as shown in Table 7.
* The numerical findings of CO\({}_{2}\) emissions indicated an increase due to the perfect combustion of biofuel with nanomaterials, as shown in Table 6. D80B20N150 showed higher CO\({}_{2}\) emissions than the rest of the fuel samples. These results are considered a promising issue for mixing nanomaterials with fossil fuels.
* The increases in the peak cylinder pressures for D80B20N50, D80B20N100, and D80B20N150 are 3%, 5%, and 8%, respectively, compared to D80B20 at a load of 200 Nm.
* Through the simulation, it was found that the maximum temperature for biodiesel blends diesel was higher than that for pure diesel; this was due to the higher hydrocarbon values of D80B20. Nano additives caused a decrease in temperatures in the combustion of biofuels.
* Finally, a lower velocity was found at the center portion of the working volume than near the walls. The swirl value is higher during the intake stroke due to the sucking operation, and then it gets reduced during the compression and combustion processes.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Fuel Type**} & \multicolumn{2}{c}{**Current Work**} & \multicolumn{2}{c}{**[PERSON] et al. [29]**} \\ \cline{2-5}  & **No Load (Kpa)** & **50\% Load (Kpa)** & **No Load (Kpa)** & **50\% Load (Kpa)** \\ \hline D80B20 & 58.2 & 76.1 & 45 & 57 \\ D80B20N50 & 59.8 & 77.2 & 46 & 59 \\ D80B20N100 & 61.3 & 78.1 & 47 & 62 \\ D80B20N150 & 62.4 & 79.8 & 48 & 64 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Validation of current results for the peak pressure of the cylinder with published data.  
by numerical modeling. A.A. helped with the numerical analysis, results analysis, and article writing. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors.  
The authors are obliged to the University of Technology, Baghdad, Iraq for providing the Energy and Renewable Energies Technology Center.  
The authors declare no conflicts of interest.