Biodiesel fueled combustion performance and emission characteristics under various intake air temperature and injection timing conditions

Abstract The purpose of this investigation is to clarify the combustion performance and exhaust emissions characteristics of biodiesel fueled compression ignition diesel engine under various intake air temperature and injection timing conditions. In order to clearly figure out the effect of intake air temperature, the flow rate of intake air was controlled at constant value before heating air. In addition, the engine speed and fuel injection quantity were fixed. Hence, the charging efficiency is constant even if the intake air temperature changes. At the injection timing BTDC 6° and 9°, high IMEPnet occurred and less NOX and HC were emitted. Here, as the intake air temperature increased, the vaporization characteristics of the fuel were improved and the ignition timing advanced close to TDC. Also, it was confirmed that the combustion duration prolonged. As a result, when the intake air temperature increases from 20 °C to 100 °C, IMEPnet increased slightly (0.39 → 0.41 MPa) owing to decreasing negative work and THC (0.85 → 0.51 g/kWh) and CO (3.72 → 1.34 g/kWh) emissions decreased, but NOX emission increased slightly (3.69 → 4.82 g/kWh). In addition, although the diameter of the most emitted PM increased relatively, the number decreased.