With the development of the society, the emission laws are increasingly strict, and EGR and multiple pre-injection strategy can effectively reduce emissions. In order to study the influence of EGR rate and pre-injection on the emission and performance of engine, a computational fluid dynamics (CFD) simulation model was established based on GT power. By changing the EGR rate, the number of pre-injection and the amount of pre-injection, the best technology coupling point is explored. The results show that EGR can effectively reduce the generation of NOx, but it will lead to the increase of soot production and the decrease of power; pre-injection can improve the trade-off relationship between NOx and power.

Through adding nitro-based fuel additive into diesel fuel,the influences of additive on engine performance, gaseous emission, particle number concentration and exhaust smoke were studied on a test bench. Meanwhile, the functioning mechanism and combustion characteristics were studied through constant volume combustion vessel. The system is composed of high pressure common rail fuel injection system, high pressure constant volume combustion vessel, high speed camera, data synchronization and acquisition system. The maximum diesel injection pressure is 160 MPa, and it can be heated to 1000 K under the back pressure of 3 MPa. According to the research results, adding fuel additive can decrease both exhaust smoke and exhaust temperature of engine for european steady state cycle(ESC). Moreover, The fuel additive improved the engine’s power slightly and expanded the economic fuel consumption working area. The minimum fuel consumption rate was reduced from 204.6g/kWh to 202.2g/kWh, and the highest fuel saving rate was about 2%. After adding MAZ, the mass of the recycled particles can be reduced by about 15%,and the average smoke intensity of most operating points showed a downward trend, with a maximum drop of 55%, the NOx weighted emissions of the whole cycle decreased by more than 2%. After adding nitro-based fuel additive, the ignition delay and flame lift-off length became longer in the combustion process, but the duration of combustion was shorter, which are in accordance with chemical reaction kinetics analysis.

This paper selects 6 gasoline detergent synergists and 6 diesel detergent synergists that are mainstream in the market. The changes in mass, volume, hardness, size and surface morphology of the main components of the engine fuel supply system after being immersed in fuel containing detergent synergists for 28 days were studied,and these changes are compared with the benchmark fuel. The results show that most of the fuel detergent synergists have almost no corrosive effect on the engine fuel supply system components or are close to the reference fuel, but some gasoline detergent synergists have a slight corrosive swelling effect on the gasoline fuel supply system.

Based on two different components of lubricating oil, this paper analyzes the filtration efficiency, ash accumulation speed, vehicle WLTC emissions, fuel consumption, and CT scan on a National V emission standard engine equipped with a cGPF aftertreatment device. The results show that both oils can ensure that cGPF meets the emission and fuel consumption requirements of National VI emission standard, but oil F accumulates ash quickly before the ash accumulation of 33% in the discharge, which has a significant effect on PN reduction, and oil C accumulates ash faster after the accumulation of 33%. The effect of reducing the PN is accelerated. Oil F is based on a full calcium detergent system, which has a trend of first to slower for the collection efficiency; while oil C is based on a mixed Ca/Mg detergent system, which has a trend of first slowing and then fasting the collection efficiency. The critical point is generally about 33% of accumulated ash. For oil F, less ash is deposited in the front and middle of the cGPF, while more ash tends to deposit towards the outlet. In contrast, cGPF aged with Oil C has a relatively uniform deposition distribution.

Based on different fuel injection strategies, this paper analyzes the factors such as engine original emission smoke, exhaust temperature, soot content, wear spot diameter and kinematic viscosity. The study found that delaying injection timing, increased afterburn, engine original soot emissions, exhaust gas temperature increase, but will increase the thermal load of the parts. At the same time, the growth rate of lubricant soot and kinematic viscosity increased; The wear spot diameter at the same soot content is reduced, and the wear is reduced. In the end, the paper finally selects 1°CA BTDC as the optimal fuel injection strategy to achieve rapid aging of engine lubricating oil in order to complete the assessment of the anti-wear performance of lubricating oil.