چكيده به لاتين
Direct injection diesel engines are widely used in automotive and industrial applications. As emission standards become more stringent and the tendency to build more efficient engines increases, it is important to better understand engine performance and the characteristics and parameters that affect the engine. In this research, a heavy diesel engine with rail application has been investigated. First, engine performance and the amount of engine pollutants in standard mode are simulated in AVL Fire software, and then changes in engine exhaust gas feedback, change in spray parameters ( Spray angle, fuel spraying time, spray angle) on engine performance and engine contaminants have been studied and improved.
The results of engine analysis show that the feedback of exhaust gases leads to a decrease in the amount of oxygen entering the combustion chamber and thus a decrease in nitrogen oxides (NOx) and soot (Soot) as well as an increase in unburned hydrocarbons (UHC). In the case of maximum torque, it is improved to reach the fuel consumption at the same time and less pollution, the feedback of exhaust gases with a mass percentage of 20% is appropriate. However, in the case of maximum speed, the feedback of exhaust gases, despite the reduction of pollutants, increases fuel consumption significantly and in this case is not recommended. Regarding the change of fuel injection angle, reducing the injection angle from 150 to 138 degrees, has led to a reduction in the production of pollutants in both no-load and maximum torque modes, as well as increasing the spray angle to 162 degrees at maximum speed, improving pollutants. Is output. Regarding the change in fuel injection time, with increasing spray time, pressure and temperature decrease, followed by NOx decrease and UHC and Soot increase. Regarding the changes of cone angle in no-load and maximum torque mode, by decreasing the spray cone angle, the penetration depth of air-fuel mixture increases and leads to better penetration ignition and less pollutants. At maximum speed, due to the high volume of inlet fuel, the quality of the premixed ignition is reduced by changing the spray cone angle and the infiltration ignition is weaker.
