Study On Evaporation Characteristics Of Butanol-fatty Acid Blended Fuel

Under the trend of world energy transformation,promoting high-quality development and realizing the goal of "dual carbon",biodiesel has broad development prospects,good application market and high economic benefits.The effect of butanol on the evaporation characteristics of biodiesel was studied to solve the problem of high viscosity and poor evaporation effect of biodiesel.According to the different molecular structure,the main components of biodiesel are divided into unsaturated fatty acids and saturated fatty acids.Therefore,oleic acid and stearic acid with the same carbon chain number were selected as the typical representatives of unsaturated fatty acids and saturated fatty acids respectively for comparison.The effects of different butanol mixing concentrations and ambient temperature on the evaporation characteristics of butanol-fatty acid mixed fuel were analyzed,and the simulation was established based on the infinite conduction model.The main work was as follows:First of all,in order to study the drop evaporation characteristics of butanol-fatty acid mixed fuel,the hanging drop method was used to build an experimental platform,and butanol-oleic acid and butanol-stearic acid mixed fuel with butanol concentration of 0%,10%,20%,30% and 50% were equipped with evaporation experiments at 773 K,873K and973 K ambient temperatures.Matlab was used to extract pixels and process data from the captured images,and the normalized diameter-squared time curve was drawn.Secondly,the evaporation characteristics of butanol-fatty acid blended fuel were analyzed from three dimensions of droplet life,proportion of each evaporation stage and evaporation rate.The research showed that the characteristics of low boiling point and low viscosity of butanol could improve the evaporation effect of fuel,but low heating value would affect the energy supply of fuel,and the optimal mixing concentration of butanol was20%-30%.At the same mixing concentration,increasing the evaporation temperature can effectively promote the overall evaporation rate of the mixed droplets.It was found that the difference in evaporation characteristics between butanol-oleic acid and butanol-stearic acid is caused by the unique omega-9 cis-double bond of oleic acid.Then,it is found that droplet micro-explosion is the cause of unsteady droplet evaporation.To solve the problem that the droplet micro-explosion mechanism is not clear,a micro-explosion mechanism of two-component mixed fuel is proposed: due to the difference in the boiling point of components,bubbles formed by butanol gasification at high temperature gather in the droplet,and when the bubble pressure is greater than the surface tension of the oil film,fuel droplet micro-explosion will be triggered.The higher the ambient temperature,the more violent the microburst.The microburst intensity was defined and the number of microbursts was counted.It was found that the microburst intensity was the highest when the butanol mixture concentration was 50%,and the droplet would have multiple microbursts if the conditions were suitable.Finally,using the infinite conduction model,Matlab was used to establish the simulation of the single drop evaporation model and compared with the experimental results to verify the feasibility of the model,providing a theoretical basis for the subsequent two-component fuel single drop evaporation experiment.