Study On The Effect Of Iron-based Nano Additives On The Evaporation Characteristics Of Ethanol And Biodiesel Blended Fuel

Energy shortages and harmful gas emissions are currently two major problems that need to be overcome.Biomass diesel is a renewable energy source and has lower NOx and CO emissions than traditional fossil fuels,making it a potential alternative energy source.Fatty acid methyl ester,as a kind of biomass diesel,which is similar in calorific value to diesel,has attracted much attention in recent years.However,due to the large kinematic viscosity coefficient of fatty acid methyl esters,it seriously affects the spray effect in the cylinder.The physical and chemical properties of ethanol are complementary to fatty acid methyl esters',and the appropriate ratio of fatty acid methyl esters blended with ethanol is unclear.Nanoparticle additives can effectively increase the energy density of fuel,and can solve the problem that low energy of mixed biodiesel.However,the mechanism of the effect of nanoparticles on the evaporation of biodiesel is still unclear.In response to the above problems,this article conducts the following research:First,a high-temperature evaporation test bench for the test requirements was built.F90E10/F80E20/F70E30/F60E40("x₁x₁"in"Fx₁x₁Ex₂x₂"means the mass proportion of fatty acid methyl esters and"x₂x₂"means the mass proportion of ethanol)with a gradient of10%mass fraction.C#combined with Halcon image processing program which contained image contrast enhancement extracted the area of the droplet image in batches,and analyzed the error of the area extraction of the droplet image.Finally,the calculation error of the square of the droplet diameter was 3.5%,which was within the allowable range.Secondly,the evaporation characteristics of the ethanol/fatty acid methyl ester mixed fuel at an ambient temperature of 873K were studied.The evaporation characteristics of the mixed fuel were evaluated by the evaporation curve,the evaporation time,the proportion of each evaporation stage,the instantaneous change rate of the evaporation curve,and the standard deviation of the curve fluctuation.The results showed that F70E30 was more suitable as a base fuel.When the ethanol mass fraction was from 20%to 30%,the fuel evaporation time decreased the fastest and the evaporation volatility increased the most.As the base fuel,F70E30 was prepared with Fe₃O₄ nanofluids with mass fractions of 0.05%,0.5%,1%,and 2%respectively,and tested the independence of surfactants.To study the evaporation characteristics of nanofluids under low temperature and high temperature environment.Research methods included evaporation curve law,evaporation time,droplet image,proportion of each stage of evaporation and evaporation rate etc.The results showed that in a low-temperature environment,an increase in the concentration of nanoparticles will have an inhibitory effect on the droplets,because the nanoparticles will gather into a shell in a low-temperature environment,preventing the droplets from exchanging heat with the surrounding air.In a high temperature environment,due to the formation of local hot spots by the nanoparticles,the high thermal conductivity of the nanoparticles and the radiation to the surrounding droplets,they promoted the evaporation of the droplets,but the concentration of the nanoparticles exceeded 0.5%,which promoted the evaporation of the droplets weakly.Because high-concentration nanoparticles easily formed a spherical shell on the surface of the droplet and prevented the droplet from evaporating.Finally,a droplet multi-component evaporation model was established.The control equation was established through the liquid droplet gas phase equilibrium,gas-liquid boundary equilibrium and liquid phase equilibrium to establish the control equations combined with the physical parameters of the fuel components,calculated the evaporation rate of the fuel multicomponent,took into account the nanoparticles'influence of heat and mass transfer,and obtained the influence coefficient of nanoparticles during droplet evaporation.The established model was compared with the experimental results,and the results show that the trend of evaporation rate was relatively consistent,which provided a theoretical basis for the exploration of the law of droplet evaporation.