## 3 Result and Discussion
### Energy Analysis  
Figure 5 shows the variation in the energy distribution of different biodiesel blends with pure diesel. Power output (BP), heat lost to the exhaust gases (\(Q_{\text{exh}}\)), heat carried away by the cooling water (\(Q_{\text{w}}\)) and other unaccounted losses (\(Q_{\text{un}}\)) were the major contributors in the energy analysis. The percentage variation of BP developed compared with the pure diesel was lower by 0.76%, 1.35%, 1.94%, 2.67% and 3.64% for \(\text{SBF}_{20}\), \(\text{SBF}_{40}\), \(\text{SBF}_{60}\), \(\text{SBF}_{80}\), and \(\text{SBF}_{100}\), respectively, which is mainly because the higher biodiesel density and lower biodiesel LHV relative to diesel fuel values are connected to the use of biodiesel and its blends. In other words, when the engine is operating at the same speed, the mass flow is enhanced as compared to the same volumetric flow of fuel provided by the injection pump, which leads to higher fuel consumption and lowers the power developed [47; 48]. The water-cooling loss was increased by 1.28%, 2.67%, 4.21%, 6.59%, and 8.69% for \(\text{SBF}_{20}\), \(\text{SBF}_{40}\), \(\text{SBF}_{60}\), \(\text{SBF}_{80}\)  
Figure 5: Energy distribution of different fuel blends under full loading conditions. and \(\text{SBF}_{100}\), respectively. This is because biodiesel fuel has a large amount of oxygen, which encourages full combustion and raises the temperature within the cylinder [49], causing loss of power increases by cooling water [50]. The exhaust losses were decreased [27] by 0.35%, 0.80%,1.35%,2.34%, and 3.39% for \(\text{SBF}_{20}\), \(\text{SBF}_{40}\), \(\text{SBF}_{60}\), \(\text{SBF}_{80}\), and \(\text{SBF}_{100}\), respectively, due to the higher oxygen content present, which promotes the proper combustion and hence reduction the exhaust gases temperature [51]. As a result, the unaccounted losses were found to increase with the blends with high microalgae concentrations, and were observed as 2.11%,4.01%, 5.98%, 8.59%, and 11.31% for \(\text{SBF}_{20}\), \(\text{SBF}_{40}\), \(\text{SBF}_{60}\), \(\text{SBF}_{80}\), and \(\text{SBF}_{100}\), respectively, when compared to pure diesel [34]. Figures 6-11 represent the variation of fuel energy contribution for diesel and blends of biodiesel and diesel blend. It was observed that the percentage share of BP and Qw increases with the increase in load whereas Qexh and Qun decrease with the increase in load for diesel and all biodiesel-diesel fuel blends. it was observed that the total input energy converted to useful output was 33.12%, heat loss by cooling water was 24.02%, heat loss by exhaust gases was 19.57%, and unaccounted losses were 23.27% for pure diesel at full loading conditions of 3.7 kw [52] It was observed in Figures 6 and 7 that the percentage increases the amount of heat lost via water cooling by 2.57%,2.03%,1.85%, and 1.28% for \(\text{SBF}_{20}\) as compared to diesel for 0.92 kW, 1.96 kW, 2.92 kw and 3.7 kw loading conditions, respectively; the reason behind this is that biodiesel contains more oxygen so there is complete combustion, which increases the cylinder temperature and leads to higher losses [53; 54]. Similarly, the exhaust gas losses were decreased by 1.73%, 0.929%, 0.8%, and 0.35%, respectively, for \(\text{SBF}_{40}\) as compared to diesel for 0.92 kW, 1.96 kW, 2.92 kw and 3.7 kw loading conditions [55]. The unaccounted heat loss was decreased by 2.29%, 2.24%,1.89 and 1.71% for \(\text{SBF}_{20}\) as compared to diesel for 0.92 kW, 1.96 kW, 2.92 kW and 3.7 kW loading conditions, respectively. Figure 8: Energy distribution of SBF\({}_{40}\) fuel under different loading conditions. Figure 7: Energy distribution of SBF\({}_{20}\) fuel under different loading conditions. Figure 10: Energy distribution of SBF\({}_{80}\) fuel under different loading conditions. Figure 9: Energy distribution of SBF\({}_{60}\) fuel under different loading conditions.