## 4 Experimental Setup and Procedure
### Test Conditions and Fuels  
Diesel fuel and biodiesel blends produced from palm oil from agro-industrial liquid waste and residual sunflower oil were used in this study. In total, five types of designated fuels were investigated, as shown in Table 3.  
The percentage of biodiesel from palm oil remained up to 10%, due to national legislative standards. In general, the percentage of diesel replacement remained below 20% since research shows that below 20% biodiesel has no negative effect on the engine, and the properties of fuels remain relatively close to diesel [36; 37; 38]. The properties of diesel and biodiesel blends were measured in a Test Laboratory, following the use of the US ASTM standard tests. The properties of these fuels are shown in Table 4.  
In the experimental process, four different engine operating conditions A, B, C, and D were tested. The characteristics of each of these conditions are shown in Figure 4.  
These conditions were selected to evaluate the main conditions of engine operation. In addition, the difference between conditions A and B with C and D allows the creation of extreme conditions of pressure, temperature, and fuel flow, which allows the combustion processes of the engine to be studied in a wide range.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Property** & **Units** & **Standards** & **D100** & **PB5** & **PB10** & **PB5 SB5** & **PB10 SB5** \\ \hline Density & kg/m\({}^{3}\) & ASTM D1298 & 821.5 & 823.1 & 827.5 & 829.1 & 833 \\ Viscosity & cSt & ASTM D445 & 2.64 & 2.65 & 2.66 & 2.68 & 2.69 \\ Flash point & \({}^{\circ}\)C & ASTM D93 & 76 & 85 & 96 & 98 & 100 \\ Cloud point & \({}^{\circ}\)C & ASTM D2500 & 6.5 & 7.2 & 8.3 & 8.5 & 9.1 \\ Pour point & \({}^{\circ}\)C & ASTM D97 & 3.1 & 3.5 & 3.8 & 4 & 4.3 \\ NCP & MJ/kg & ASTM D240 & 44.05 & 43.89 & 43.25 & 42.28 & 41.67 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Physicochemical properties of the fuels.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Measuring Instrument** & **Manufacturer** & **Range** & **Accuracy** \\ \hline Thermocouple & Type K & \(-\)200–1370 \({}^{\circ}\)C & 0.1\% \\ Piezoelectric transducer & KISTLER type 7063-A & 0–250 bar & \(<\)\(\pm\)0.5\% \\ Gravimetric meter & OHAUS PA313 & 0–310 g & 1\% \\ Hot wire & BOSCH 22680 Y600 & 0–125 g/s & 1\% \\ Hall effect & NJK-5002C & 5–9999 RPM & 0.03\% \\ \hline Exhaust gas analyzer & BrainBee AGS-688 & CO\({}_{2}\) & 0 \(\div\) 9.99 vol\% & \(\pm\)0.1\% \\  & & HC & 0 \(\div\) 19.999 ppm & \(\pm\)1\% \\  & PCA\({}^{\circledR}\) 400 & NOx & 0 \(\div\) 3000 ppm & \(\pm\)0.5\% \\ \hline Smoke meter & BrainBee OPA-100 & 0 \(\div\) 99.9\% & \(\pm\)0.1\% \\ \hline \hline \end{tabular}
\end{table}
Table 2: Specifications of measuring instruments.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Nomenclature** & **Composition** \\ \hline D100 & Diesel 100\% \\ PB5 & Diesel 95\% + Palm oil biodiesel 5\% \\ PB10 & Diesel 90\% + Palm oil biodiesel 10\% \\ PB5 SB5 & Diesel 90\% + Palm oil biodiesel 5\% + Sunflower oil biodiesel 5\% \\ PB10 SB5 & Diesel 85\% + Palm oil biodiesel 10\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Nomenclature and composition of fuels.