An investigation of the effect of plateau environment on the soot generation and oxidation in diesel engines

Abstract

The plateau environment deteriorates the combustion quality inside the heavy duty diesel engine, bringing difficulties in controlling soot emissions. To study the causes of soot increase is the basis for optimizing highland engines and achieving clean operation. A multidimensional CFD model based on a 6V150 engine was developed in this study to investigate the effect of altitude on soot formation and oxidation processes. The comparison between experimental data and numerical results showed that the model was deemed to be able to predict in-cylinder activities at various altitudes. The simulation results showed that when the diesel engine was operated at high altitude, the mismatch between fuel and air led to more soot formation but less oxidized. The wall impingement of fuel droplets occurred at altitudes above 3000 m and soot emissions rose sharply when the altitude exceeded 4000 m. It can be concluded that the engine recalibration strategy may mitigate the increase in soot at altitudes below 3000 m, but may not be very effective when the engine is operating at 4000 m. In addition, the application of oxygenated fuels that can provide more hydroxyl radicals may be an alternative solution to mitigate soot emissions from diesel engines operating in very high altitude regions.