Influence Of Fuel Characteristics On Combustion And Emissions Of Dual Fuel Engine

In recent years,my country has actively implemented the energy diversification strategy to adjust the energy structure and built a system of mutual transformation of various energy forms to ensure the country’s energy security.At the same time,in response to the demand for ultra-high efficiency and near zero emissions,internal combustion engines are highly efficient and clean.The study of combustion modes has become a hot issue,so it is imperative to apply clean alternative fuels that match the characteristics of the advanced combustion modes of internal combustion engines to achieve high-efficiency and clean combustion.This paper uses thermodynamic tests and simulation methods to study the combustion process and pollutant generation process of a coal-based synthetic diesel/gasoline dual-fuel engine,and compares it with traditional petrochemical diesel.In view of the problems of coal-based synthetic diesel/gasoline dual-fuel engines,two oxygen-containing fuels,n-butanol and polymethyl dimethyl ether(PODE),are further used as additives for coal-based synthetic diesel to adjust the physical and chemical properties of direct injection fuel to explore its reduction in pollution The potential for emissions.And through the synergistic control of fuel characteristics and combustion boundary conditions,the potential of oxygen-containing fuel additives to reduce pollutants in dual-fuel engines is explored.The main research contents and conclusions are as follows:(1)By means of simulation calculation,the influence of coal-based synthetic diesel as direct injection fuel on the combustion and emissions of dual-fuel injection engines is studied.The results show that direct injection of coal-based synthetic diesel can continue to improve thermal efficiency on the basis of direct injection of traditional petrochemical diesel,and the proportion of gasoline that achieves the highest thermal efficiency compared with direct injection of diesel is smaller.In addition,in the combustion process of coal-based synthetic diesel/gasoline engines,there is a two-stage combustion phenomenon dominated by premixed compression ignition of highly reactive fuels and multi-point spontaneous combustion of low reactive fuels.In dual-injection mode,direct injection of coal-based synthetic diesel has a shorter combustion duration than direct injection of diesel,and low-reactivity fuel has a greater proportion of multi-point spontaneous combustion,so particulate emissions are slightly higher than traditional petrochemical diesel,and NOx emissions Slightly lower than traditional petrochemical diesel.At the 60%gasoline ratio with the highest thermal efficiency,the advancement of the direct injection fuel injection timing makes the second stage heat release gradually dominate,indicating that the thermal efficiency will increase,but the NOx emissions will increase significantly,and the particulate emissions will first decrease and then increase..(2)On the basis of the above simulation calculations,the effects of coal-based synthetic diesel and its oxygen-containing mixed fuel on the combustion and emissions of dual-fuel injection engines are experimentally studied.The results show that the use of n-butanol and poly methyl dimethyl ether as direct injection fuel additives on dual-fuel engines can effectively reduce pollutant emissions.Among them,the particulate,CO,NOx and HC emissions after the addition of polymethyl dimethyl ether are all Reduced.After adding n-butanol,the effect of reducing particulate and CO emissions is obvious,and NOx changes little.After adding n-butanol,the engine runs smoothly,and the influence of gasoline ratio changes is significantly reduced.(3)When studying the influence of direct injection fuel oxygen content on pollutant generation,it is found that the increase of direct injection fuel oxygen content has little effect on HC emissions,NOx emissions increase linearly,and CO and particulate emissions decrease.Among them,when the mixing ratio of n-butanol in direct injection fuel exceeds 20%,the decreasing trend of particles decreases.(4)Through fuel characteristics and expected conditions,it is found that when auxiliary control is used to explore high-efficiency light emission,the fuel injection timing is 6.5°CABTDC～7℃A BTDC,and the direct injection fuel has a blending ratio of n-butanol from 25%to 30%.The heat in the indicated area exceeds 2%,and the concentration percentage is 15bar/℃A.It is synthesized with coal-based synthesis with the same fuel injection timing.The particle mass concentration is reduced by 50%to 55%,and the CO emissions are reduced by 10%to 20%.HC emissions increase by 20%to 25%,and NOx increases by 40%to 45%.