Study On Single Droplet Evaporation Characteristics Of Water Emulsified Diesel Based On Image Processing

According to market statistics,at present,China's auto market is still dominated by fuel vehicles,and the number of fuel vehicles will continue to increase yearly,leading to serious environmental and energy problems.Research on renewable alternative fuels is increasingly important to reduce traditional energy consumption and pollutant emissions.Emulsified fuels have a special microstructure that produces a unique micro-explosion during evaporation.Many studies have shown that this phenomenon has a significant effect on promoting in-cylinder oil and gas mixing,optimizing in-cylinder combustion process,reducing fuel consumption,lowering the maximum combustion temperature in the cylinder,and reducing nitrogen oxides and particulate matter emissions.Present researches on emulsion fuel focus on the effect of macroscopic factors on its micro-explosion phenomenon,while the study of microstructure(dispersion phase diameter)on the micro-explosion of emulsified fuel is few.Therefore,it is of practical significance to have a deep understanding of the different microstructures of emulsified fuels and the effects on the evaporation characteristics of emulsified fuels.Meanwhile,in order to accurately study the influence mechanism on droplet evaporation characteristics using the large number of experimental images collected during the research process,adopting appropriate image processing methods is a key point in the work of this paper.Thus,an accurate,automatically recognized and user-friendly image processing program was developed.In order to obtain accurate microstructure of water emulsified diesel,a micro-structure image processing program was developed in this paper for emulsified diesel,which was used for the diameter and position of the dispersed phase in the emulsified diesel image obtained by an optical microscope.The microstructure image with relatively complex background is transformed into a binary image with only dispersed phase information,and the diameter of the dispersed phase in the image is further extracted by the method of pattern detection.In order to quantify the droplet evaporation process of water-emulsified diesel,an image processing program for the main droplet region in the images of the extraction droplet evaporation process was developed.This program can separate the main droplet from the background of the image as well as the main droplet from the thermocouple where the droplet is suspended,resulting in a simple image containing only the area of the droplet.By using the characteristic parameters such as the shape of the divided droplet region,obtaining the calculation and statistics of the relevant parameters,the evaporation process of the droplets can be clearly understood.Subsequently,in order to quantitatively analyze the evaporation characteristics of water emulsified diesel droplets,an image processing program for identifying the main droplet region and analysing droplet variation law in the droplet evaporation experiment image was developed.This program separates the main droplet from the background of the image and separates the main droplet from the thermocouple that hangs the droplet,resulting in a simple image containing only the area of the droplet.By using the characteristic parameters such as the shape of the divided droplet region for calculating and counting the relevant parameters,accurate and quantitative analysis of the evaporation process of the droplets can be performed.In this paper,the droplet suspension method was used to study the droplet evaporation characteristics of water-emulsified diesel with different microstructures(dispersed phase diameter).After the images being processed by the image processing programs mentioned above,the obtained data is calculated and counted,then the trend of the evaporation rate,the normalized projection area,the maximum expansion scale,the cumulative micro-explosion intensity,the micro-explosion frequency,etc.of the droplet evaporation process are obtained.These data analyzes the effects of different dispersed phase diameters on the characteristic parameters of the droplet evaporation process.Finally,in order to optimize the image processing program of this paper while using,a suspension method was used to study the evaporation characteristics of water-incorporated emulsified diesel droplet with different microstructures(dispersion phase diameter).Through the accurate and automatic recognition of the image processing program,the digital processing of the experimental image is completed,then the trend of the evaporation rate,normalized projection area,maximum expansion scale,cumulative micro-explosion intensity and micro-explosion frequency of the droplet evaporation process are obtained.The effects of different dispersed phase diameters were analyzed on these characteristic parameters of the droplet evaporation process.