# Pollutant Emissions and Combustion Efficiency Assessment of Engines Using Biodiesel
## 3 Results and Discussion
### Experimental Test Results with the Monocylindrical Engine  
The results obtained with the monocylindrical engine are presented in Figure 7. In comparison to pure diesel, it was observed that the B50 blend displayed a decrease of 11.5% in chimney temperature (temperature measured in the exhaust pipe) with respect to the B0; also, there was a decrease in the percentage of oxygen (O\({}_{2}\)) in the exhaust gases, showing a decrease of 1.14% for the B50 test with respect to B0 (see Figure 7B).  
Figure 7C shows the decrease in the percentage of hydrocarbons present in the exhaust gases; this decrease for the B50 blend was 12.5% with respect to pure diesel. The percentage decrease in hydrocarbons shows a positive signal of combustion because this is the main component of air pollution. Figure 7D shows a decrease in CO ppm in the B50 blend by around 3.99% with respect to pure diesel B0; also, there was a decrease in blends B30 and B40 behavior, which is positive because carbon monoxide is one of the main pollutants from low fuel combustion.  
In Figure 7E, NO was significantly improved to 62.5% in B50 with respect to B0. Similarly, NO\({}_{2}\) showed an increase of this compound in each blend, observing a maximum value of 46.33 ppm, representing an increase of 188.8% with respect to B0. Figure 7E shows an increase in NOx in ppm, and this represents an increase of 114% with respect to B0. Nitrogen oxides cause health diseases such as organ conditions, lung infections, and respiratory failure.  
Figure 7F shows the behavior of SO\({}_{2}\); the results showed a decrease in SO\({}_{2}\) mainly for blends B30, B40, and B50, observing the minimum value in B20 with a value of 3.6 ppm. This represents a positive result for the environment and human health because this compound can cause degeneration in people's health, from irritation and inflammation of the respiratory system to pulmonary conditions and insufficiencies.  
In addition, this compound, when mixed with rain, can be transformed into sulfuric acid, causing \"acid rain\", so this compound is of the utmost importance to reduce n vehicle exhaust. In articles related to fuel blends, the use of biodiesel as biofuel, with various advantages, has been seen as positive. Toxicity levels are lower in biodiesel than those presented by diesel, and its performance has a minimal difference. Compared to fossil diesel, biodiesel does not produce sulfides, net carbon dioxide, carbon monoxide, or particles of matter, and there are no smoke or hydrocarbon emissions [32]. An analysis has been made of biodiesel produced with rapeseed oil, which is gaining acceptance in the biofuel  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Test** & **Result** & **Methodology** \\ \hline Dynamic Viscosity mpa\textgreater{}@ 40 \({}^{\circ}\)C & 3.6499 & ASTM D7042 \\ \hline Kinematic Viscosity mm\({}^{2}\)s @ 40 \({}^{\circ}\)C & 4.2063 & ASTM D7042 \\ \hline Density g/cm\({}^{3}\) @ 15 \({}^{\circ}\)C & 0.8865 & ASTM D4052 \\ \hline Flashpoint \({}^{\circ}\)C & 150 & ASTM D93 \\ \hline Acid number mg KOH/g & 0.424 & NMX-F-101-SCFI-2012 \\ \hline Acid number \% & 0.213 & NMX-F-101-SCFI-2012 \\ \hline Calorific value MJ/kg & 39.8785 & ASTM D4809 \\ \hline Oxidative stability (h) & 3.66 & ASTM D7525 \\ \hline Cold filtered \({}^{\circ}\)C & \(-4\) & ASTM D6371 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Characteristics of biodiesel.  
market due to the environmental and economic benefits that it provides. Some publications have indicated that rapeseed biodiesel has almost the same performance as fossil diesel and reduces ignition delay, in addition to considerably reducing polluting emissions compared to biodiesel from other raw materials [33]. In a recent study to evaluated exhaust emissions with blends of biodiesel in a single-cylinder diesel engine, it showed that the earlier the injection, the lower the complete combustion and engine performance for all engine loads due to the increased amount of biodiesel cetane [34].