# Heat Release Rates of Straight Soybean and Diesel Oil Blends in a Compression Ignition Engine
## 2 Experimental Procedure
### Experimental Setup  
The experimental setup consists of a 14.7 kW, 4-stroke single-cylinder, direct injection diesel engine (Yanmar, model YT22E, Yanmar Co., Ltd., Osaka, Japan) coupled to an electromagnetic dynamometer (Schenk, model W70, Schenck RoTec GmbH, Darmstadt, Germany). The dynamometric bench is equipped with a fuel supply system, a measurement system of the in-cylinder pressure, an air measuring system, and a control and data acquisition system. Figure 1 shows a schematic diagram of the experimental setup. Technical specifications of the direct injection diesel engine are shown in Table 4.  
An electric heater comprising an aluminum tube (12.7 mm diameter), electrical resistance of 119 \(\Omega\), and ceramic insulation was manufactured to heat the vegetable oil blend before it entered the engine. An electromagnetic 3/2 valve was installed to switch to the fuel employed. This enables the passage of diesel oil from the original tank or the fuel under test. The fuel consumption was measured using an electronic balance (Marte, model AD5000) with serial communication. The instant reading of the data allowed the calculation of the fuel flow. The engine torque was measured with an extensometer-type load cell installed on the dynamometer arm. The speed was measured with an incremental encoder 360 pulses/revolution (Autonics, model E40S, Seoul, Republic of Korea). The inducted air mass was measured with a hot-film mass air-flow meter (Bosch, model HFM 2, Gerlingen, Germany). An air reservoir was coupled between the intake manifold and the air-mass meter to ensure uniformity of the flow and the measurement of \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Fuel**} & **Temperature** & \multirow{2}{*}{**Density (kg/m\({}^{3}\))**} & **Dynamic** & **Surface Tension** \\  & (\({}^{\circ}\)C) & & **Viscosity** & **(mPa-s)** & **(mN/m)** \\ \hline Diesel oil & 25 & 828.7 \(\pm\) 3.0 & 3.51 \(\pm\) 0.22 & 27.76 \(\pm\) 0.40 \\
50/50\% \(v/v\) & 25 & 871.7 \(\pm\) 2.2 & 13.19 \(\pm\) 0.43 & 30.12 \(\pm\) 0.28 \\ soybean/diesel & 85 & 832.9 \(\pm\) 2.2 & 3.62 \(\pm\) 0.18 & 25.54 \(\pm\) 0.28 \\
80/20\% \(v/v\) & 85 & 858.8 \(\pm\) 2.7 & 6.47 \(\pm\) 0.23 & 26.83 \(\pm\) 0.32 \\ soybean/diesel & 85 & 876.1 \(\pm\) 3.3 & 9.53 \(\pm\) 0.37 & 27.72 \(\pm\) 0.39 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Measurements of physical properties of the fuels tested. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Property** & **Soybean Oil** & **Diesel Oil** \\ \hline \(HHV\) (kJ/kg) & 39,440 & 45,345 \\ \(LHV\) (kJ/kg) & 36,950 & 42,435 \\ Carbon, C (\%) & 77.67 & 85.79 \\ Hydrogen, H (\%) & 11.52 & 13.52 \\ Sulfur, S (\%) & \textless{}0.04 & \textless{}0.04 \\ Nitrogen, N (\%) & 0.02 & 0.05 \\ Oxygen, O (\%) & 10.76 & 0.61 \\ Molecular formula & C\({}_{\text{57.4}}\)H\({}_{\text{101.5}}\)O\({}_{\text{6}}\) & C\({}_{\text{12}}\)H\({}_{\text{26}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Values of \(HHV\), \(LHV\), C, H, S, N, and O of soybean and diesel oils. the air-mass rate. Temperature and relative humidity of the air inducted were measured through a humidity sensor and a temperature sensor installed before the mass air-flow meter. A thermocouple was installed in the intake manifold, close to the intake valve, to register the air temperature inducted. Additionally, a set of thermocouples was installed at the engine cooling water outlet, the exhaust manifold, the heater outlet, and the injection pump inlet. An electronic control and data acquisition system was developed with LabVIEW software 2011 [38] using two acquisition boards to register the different variables. Experimental Testing  
The tests were performed at the maximum flow rate of the injection pump. In each test, the engine operation was started with diesel fuel until the heating period was completed, i.e., when the cooling water temperature reached 60 \({}^{\circ}\)C. The diesel oil was then replaced by the fuel under test. After achieving stable operation with the new fuel (steady readings),