Mechanism Reduction Of PODE₃/DEM Blended Fuel And Its Effect On Engine Combustion Process And Emission Generation

In recent years,the world’s industrialization has accelerated,energy shortages and environmental pollution caused by the continuous consumption of fossil fuels have become increasingly serious.people have begun to have more and more urgent demands for alternative fuels for internal combustion engines.PODE3 and DME have been widely welcomed for their simple production,low price and convenient storage.More importantly,PODE3 and DME have a higher cetane number.Secondly,its high oxygen content can effectively reduce Soot emissions.It is an ideal alternative fuel for diesel that can effectively reduce Soot emissions.The effective combination of the two has important practical significance for energy saving and emission reduction of internal combustion engines.However,the combustion reaction mechanism of PODE3/DME is not concise enough for 3D numerical simulations,and PODE3 and DME as new alternative fuels for diesel have not been fully studied.Therefore,the work of this article aims to develop a small and accurate The PODE3/DME reaction mechanism is verified and analyzed.In addition,this mechanism is used for in-cylinder verification of diesel engines to study the generation and emission of Soot and NOX.In this paper,PODE3 and DME are used as characterization fuels,and a reduced model of PODE3/DME blended fuel is constructed.First,the detailed mechanism of PODE3 and DME is combined to obtain the detailed mechanism of PODE3/DME mixed fuel.The detailed mechanism is simplified using DRGEP,sensitivity analysis method and isomer lumpimg methods,and finally it contains only 65 components and 308 reaction equations.After analyzing the main reaction pathways,it can be found that no carbon-carbon double bonds(C=C)are formed during the oxidation reaction of PODE3/DME,which shows that the fuel can effectively reduce Soot emissions.Based on experimental data and other simplified results,the simplified mechanism of PODE3 and DME was verified in a fast compressor.It was verified that PODE3 was at pressures of 1.0MPa and1.5MPa,equivalent ratios were 0.5,1.0 and 1.5,and DME was at pressures of 1.0MPa and 1.5MPa.The ignition delay time and laminar flame speed at 11 atm and 25 atm,equivalence ratios of 0.5,1.0 and 2.0show that the reduced mechanism is well verified and can be a good substitute for the detailed mechanism.Finally,through the Converge in-cylinder verification of the diesel engine,the cylinder pressure and heat release rate at engine speeds of 1600 r/min and 2000 r/min and equivalence ratios of0.1,0.18 and 0.28 are verified.The result shows that the simulated values are in good agreement with the experimental values.The reliability of the simplified mechanism can be verified,which lays the foundation for the computational fluid dynamics numerical simulation of mixed fuel combustion in the cylinder.Finally,by studying the influence of EGR rate on the combustion and emission characteristics of three different fuel mixture ratios,the emission of pollutants is further reduced.By comparison,it can be seen that as the EGR rate increases,the emissions of Soot and CO increase,and the emissions of NOX decrease.By adding the EGR system,not only the fuel utilization rate is improved,but also the NOX emission is reduced,which has important practical significance for energy saving and emission reduction.