Effects of Injection Parameters on the Performance of a Diesel Engine at Different Altitudes

The influence of injection advance angle, injection pressure and cyclic fuel injection quantity on combustion and performance at different altitude conditions were experimentally studied on a plateau environment simulating test bed at full load(2 300N•m)and part load(500 N•m)of 1 500 r/min. The results show that, with the fuel injection advance angle increasing under full load, the ignition delay period, maximum combustion pressure and pressure rise rate increase, but the rate decreases with the increase of the altitude. Meanwhile, with the injection advance angle increasing, the engine torque takes a change of first increase and then decrease at the altitude of 0 km and 3 km and monotonically increases at 5 km, while the exhaust temperature decreases steadily. As the injection pressure increases, the combustion phase is advanced, leading to increase in the maximum combustion pressure, the pressure rise rate and the torque output. At part load operations, the brake specific fuel consumption decreases steadily with the increase of injection pressure. Furthermore, with the increase of the cyclic fuel injection quantity, the torque, the exhaust temperature and the cylinder pressure increase, but the maximum pressure rise rate increases from 0 km to 3 km and decreases at 5 km. It is found that each increment of 1 km in altitude gives a reduction of the optimal cyclic fuel injection quantity by 5.81% at full load, the optimal injection advance angle increases by 1.2°, CA and 0.8°, CA and the optimal rail pressure increases by 4MPa and 3MPa, respectively at full load and part load conditions. © 2020, Editorial Office of the Transaction of CSICE. All right reserved.