Study On Spray Gas-liquid Characteristics Of Biodiesel/N-amyl Alcohol Mixture

With the increasingly strict emission regulations in China,energy saving and emission reduction has become a research hotspot in the transportation industry.The rapid development of science and technology leads to a sharp increase in global demand for energy.Under the great pressure of energy shortage,it is urgent to find one or more efficient and renewable alternative fuels.Biodiesel made from various animal oils and seeds and fruits of plants has a higher calorific value,but it cannot be used as a substitute for diesel because its viscosity is higher than that of diesel.As a kind of biomass oxygenated fuel,n-pentanol is higher than methanol,ethanol,butanol and other cetane values,and has better compression ignition,and the evaporation latent heat of n-pentanol is lower,which can improve the cold start performance of the engine.The mixture of biodiesel and n-amyl alcohol is expected to be a clean and efficient alternative energy source.Since the combustion characteristics of the mixed fuel are affected by its spray characteristics,it is of great significance to study the spray characteristics of biodiesel/n-amyl alcohol mixed fuel.This article debugging and set the constant volume bomb optical visualization spray test rig,the play and schlieren method took B100(pure biodiesel),BP20(amyl alcohol,20% to80% of biodiesel)and BP40(amyl alcohol,40% to 60% of biodiesel)three kinds of fuel under different injection pressure(80,110,140 MPa)and different ambient temperatures(350,395,435 ?),the development of spray images.The liquid phase image of the spray was captured by the direct shot method,and the whole spray image including the two phases of the spray was captured by the schlieren method.The corresponding image processing program was written by MATLAB to obtain its image characteristic parameters,and these parameters were drawn into a graph to analyze the spray characteristics of the mixed fuel.The analysis results showed that:Mixing a certain proportion of n-amyl alcohol in pure biodiesel can effectively improve the crushing fog of fuel oilChemical properties,make more liquid phase fuel vaporize into gas phase fuel in the spray front,promote the uniform mixing of fuel and air;The higher the mixing ratio of n-amyl alcohol,the stronger the evaporation degree of the mixed fuel,and the better the gas-liquid separation.Increasing injection pressure can enhance the crushing and evaporation effect of the mixed fuel.Under the condition of high injection pressure,BP40 can effectively reduce the wet wall phenomenon of oil bundle.Under the condition of low injection pressure,BP20 and BP40 can still maintain good evaporation performance.Increasing the ambient temperature can promote the vaporization of liquid fuel in the spray front to gas phase fuel,promote the mixture of fuel and air,improve the air utilization rate,and reduce the emission of CO and PM and other pollutants.At 350? and 395?,the improvement of evaporation performance of B100 was not obvious with the increase of temperature,but BP20 and BP40 still maintained good evaporation performance.When the ambient temperature was lower than 395?,the liquid phase penetrating distance of the three fuels changed little when the ambient temperature was raised,but the length of the gas phase increased significantly.When the ambient temperature reaches 435 ?,the spray liquid penetrating distance of the three fuels is shortened and the length of the gas phase is further increased..