# Analysis of Biodiesel Influence on Unregulated Gaseous Emissions of Diesel Motor Vehicles
## 2 Experiment Conditions  
The practical base for the experimental measurements created a diesel engine equipped with a direct fuel injection system of the common rail type, which is normally installed in a wide range of diesel engine vehicles. The tested diesel mixtures were achieved by mixing biodiesel with pure diesel using various mixing ratios. The pure diesel fuel contained less than 10 ppm of the sulfur, such that it was the so-called ultra-low sulfur diesel (ULSD-F). Biodiesel was obtained from waste oil according to the valid European standard EN-14214. The individual diesel mixtures were determined, taking into consideration the previous experiments, as follows: B-U (25:75) (25% biodiesel and 75% ULSD-F), B-U (50:50), B-U (75:25). The most important technical parameters of the tested diesel engine are summarized in Table 1.  
The experimental testing system was created by the placement of the tested diesel vehicle engine on the testing dynamometer according to Figure 1. The gas analyzer was used to perform analysis of regulated gaseous emissions, i.e., for the analysis of nitrogen oxides (NO\({}_{\chi}\)), hydrocarbons (HC), carbon monoxide (CO) and particulate matter (PM). Analysis of unregulated emissions (such as acetaldehyde, 1,3-butadiene, formaldehyde, ethene, propene and BTX hydrocarbons) was performed using the multi-component gas analyzer. The calibration of this analyzer was repeated before each measurement. The fuel consumption was measured by the electronic flowmeter. The characteristics of the experimental biodiesel and ULSD-F are presented in Table 2. \begin{table}
\begin{tabular}{c c} \hline \hline
**Type** & **4-Cylinders, Common-Rail Diesel** \\ \hline Compression ratio (CR) & 16.2:1 \\ \hline Bore \(\times\) stroke & 81 \(\times\) 95.5 mm \\ \hline Displacement & 1968 cm\({}^{3}\) \\ \hline Rated output & 110 kW \\ \hline Engine speed & 3500–4000 rpm \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The experimental engine parameters. Figure 1: The experimental system. The European Stationary Cycle (ESC) was used in order to analyze the influence of the fuel mixtures on the gaseous emissions. The ESC testing parameters are described in Table 3 and in Figure 2. The first regime of the testing process measurement was the stable operation of the tested engine. This first phase is characterized by the constant temperature of the coolant, lubricating oil and exhaust gases. Afterwards, the engine operational parameters were monitored at five-minute intervals; namely in the form of mean values of the measured operational parameters. The experiments were repeated two times with regard to the elimination of potential random failures. The results obtained from the experiments agree with the 97% confidence level. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Biodiesel** & **ULSD-F** \\ \hline Density, 15 (kg\(\cdot\)m\({}^{-3}\)) & 860 \(\div\) 920 & 820 \(\div\) 845 \\ \hline Viscosity (40 \({}^{\circ}\)C) (mm\({}^{2}\cdot\)s\({}^{-1}\)) & 3.8 \(\div\) 5.1 & 1.9 \(\div\) 4.1 \\ \hline Cetane number & min 55 & min 47 \\ \hline Sulphur content (mg\(\cdot\)kg\({}^{-1}\)) & max 10 & max 10 \\ \hline Heat of evaporation (k\(\cdot\)kg\({}^{-1}\)) & 252 \(\div\) 295 & 285 \(\div\) 338 \\ \hline Flash point (\({}^{\circ}\)C) & 103 & 82 \\ \hline Carbon content (wt \%) & 81.6 & 97.2 \\ \hline Hydrogen content (wt \%) & 12.4 & 13.4 \\ \hline Oxygen content (wt \%) & 10.5 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The characteristics of the experimental fuels.