Study On Optimization Of Injection Parameters Of Internal Combustion Engines Supplied With Oxygenated Mixing Fuel

In the face of energy consumption,environmental pollution,increasingly stringent emission regulations and the impact of new energy vehicles,how to achieve efficient clean combustion has become the primary problem in the development of internal combustion engines.Exploring the engine purification measures,optimizing the combustion process,achieving a new combustion mode that simultaneously reduces fuel consumption,NOx and PM,and reducing the dependence on post-processing,is always the direction of the development of internal combustion engines.Based on the National Natural Science Foundation of China project “Study on transient combustion and particle generation mechanism of stratified activation controllable compression ignition internal combustion engine based on the combined mechanism of fuel oxygen and environmental oxygen”,this paper is based on the synergistic control of fuel physical and chemical properties and combustion boundary conditions.The idea,burning diesel fuel and its mixed fuel with n-butanol,studied the correlation between fuel physicochemical properties and engine combustion process and pollutant emissions,and clarified the fuel injection boundary conditions for oxygen-containing mixed fuel under different oxygen concentration distribution forms.The effects and differences of combustion and emissions.Using statistical methods,the effects of fuel injection parameters on NOx emissions and exhaust smoke of oxygenated fuels were analyzed.The multi-objective particle swarm optimization algorithm is introduced into the fuel injection parameter optimization problem to reveal the potential of fuel injection parameters to reduce NOx emissions and smoke,and a reasonable fuel injection strategy is proposed.Based on the fuel injection control system and the simulated supercharging system,the active control and flexible adjustment of the engine intake flow and composition,fuel injection boundary conditions are provided,which provides the basic conditions for the smooth progress of the test.The combustion analyzer is the core to form the combustion.The collection analysis and emission test system realizes on-line analysis and real-time recording of in-cylinder combustion conditions and pollutant emissions,avoiding human error in emission data collection,improving test repeatability and data accuracy.Provide a stable and reliable foundation.Research indicates:1.Physical and chemical properties of fuel are important factors affecting combustion and emissions.The engine burns diesel fuel and oxygen mixing fuels B15 and B30.Due to the decrease of cetane number and the latent heat of vaporization of Oxygenated Mixing Fuel B15 and B30,the retardation period is prolonged,the premixed combustion ratio is increased,and the exhaust smoke is increased.The degree is significantly reduced(more than 60%),NOx emissions increase only when the oxygen concentration in the cylinder is sufficient.The concentration of nuclear particles and total particles increased,and the concentration of accumulated particles decreased significantly.2.Under the uniform distribution of oxygen concentration in the cylinder,the single injection of fuel injection pressure and timing has a significant effect on the combustion and emission of diesel-n-butanol oxygenated blended fuel B15.Increasing the fuel injection pressure,the concentration of the in-cylinder mixture is significantly reduced,the extinction smoke is significantly reduced,the NOx is at a higher emission level,almost linear growth,the concentration of nuclear particles increases,and the concentration of accumulated particles is significantly reduced.As the injection timing advances,the CA50 moves forward significantly,NOx increases significantly,the extinction smoke decreases,the nucleate particles increase,and the accumulated particles decrease.Therefore,in the case of a homogeneous distribution of oxygen concentration in the cylinder,in order to simultaneously reduce NOx and particulate emissions,the oxygen-containing mixed fuel B15 is not suitable for adopting a higher fuel injection pressure and an earlier injection timing.3.Under the stratified distribution of oxygen concentration in the cylinder,the effect of injection pressure and timing on the combustion and emission of B15 is weakened by single-stage injection.With the increase of injection pressure,there is no significant change in cylinder pressure peak and cylinder temperature,NOx rises slowly,and the effect of smoke reduction is gradually weakened,but there is still a low level of NOx and accumulated particulate emissions relative to the oxygen concentration homogeneous distribution.With the advance of injection timing,CA50 is significantly advanced,NOx is gradually increased,and the extinction smoke is significantly reduced.Compared with the homogeneous distribution of oxygen concentration,NOx and total particulate emissions are at a lower level;only at the late injection timing.The matte smoke in the in-cylinder oxygen concentration layer is higher than the homogenization.Therefore,in the incylinder oxygen concentration layered form,the fuel injection pressure and the advance injection timing can be appropriately increased to further reduce the extinction smoke.4.Under the homogeneous and stratified distribution of oxygen concentration in the cylinder,the oxygen mixing fuel B15 is used,and the two-stage injection is used.The main pre-injection interval and the pre-injection amount have significant effects on NOx emission and smoke.As the main pre-injection interval increases,the concentration of NOx emissions and nuclear particles increases,and the extinction smoke and accumulated particles decrease significantly.As the preinjection increases,both NOx emissions and extinction smoke increase.The oxygen concentration homogenization is not much different from the NOx emission under the stratified form,and the extinction smoke in the oxygen concentration layered form is generally slightly lower than the homogenization.Therefore,for the oxygen mixing fuel B15,when two-stage injection is employed,it is suitable to use a smaller pre-injection amount and a moderate main pre-injection interval.5.For the oxygenated mixing fuel B15,the statistical analysis results show that the fuel injection boundary conditions have a significant effect on NOx and smoke.The main injection timing,injection pressure and pre-injection amount have a great influence on NOx.The main spray timing,injection pressure,and main pre-injection interval have a significant effect on smoke.6.The multi-objective optimization results based on the Oxygenated Fuel injection parameters show that when using the oxygenated mixing fuel B15,the two-stage injection with pre-injection has great potential in reducing NOx emissions and extinction smoke.The fuel injection pressure,main injection timing,main pre-injection interval and pre-injection amount were selected as test factors.The orthogonal test was designed.The regression model was established based on the test data for NOx and extinction smoke.The multi-objective particle swarm optimization algorithm was used to explore and pass.Optimize fuel injection parameters to reduce the potential for NOx and smoke.The injection pressure is 110 MPa,the main injection timing is-5.6°CA ATDC,the pre-injection amount is 9.4%,and the main pre-injection interval is 17.7°CA,which can reduce the NOx to 476 ppm and the smoke to 1.0%at 1400r/min and 50% load,compared with the original load of the original machine,when the average oxygen concentration in the cylinder is 20.7%,the diesel fuel is reduced by 26.2% and 9.1%,respectively,and the fuel consumption rate is not deteriorated.