Performance Assessment of a Diesel Engine Fueled with Biodiesel in a Plateau Environment

Biodiesel has a higher oxygen content and a higher cetane number, which can compensate for the intake oxygen deficiency in diesel engines in a plateau environment to a certain extent. However, the decreased air density makes biodiesel fuel spray atomization and evaporation more difficult due to its higher density and kinematic viscosity, reducing the quality of the air-fuel mixture. The investigations in this study focus on the effects of biodiesel blending ratios and their coupling with injection timing on diesel engine performances under varying altitude conditions. The results show that as the altitude increases, using a high proportion of biodiesel-blended fuel results in a lower degree of torque reduction. The torque reduction of B100 is 14% lower than that of baseline at an altitude of 4500 m. In addition, when the altitude increases by 2000 m, the optimal fuel injection timing is delayed by 4° CA, regardless of the biodiesel blending ratio. The low-temperature combustion heat release ratio of biodiesel engines slightly increases with the delay of injection time, which is increased with the biodiesel blending ratio. For B100 fuel, increasing the pilot injection quantity under high-altitude conditions helps to improve the heat release rate during the early and late stages of combustion and reduce expansion losses.