Study On Micro-explosion Characteristics Of Biodiesel And Its Blended Fuel

Full or partial use of renewable energy is an effective way to achieve energy conservation,emission reduction and sustainable development of fossil energy.In this paper,two experimental platforms are set:the common rail heating system under constant terperature and the tube furmace heating system.Using these two experimental platforms,this paper study the expansion,ejection and micro-explosion characteristics of biodiesel,aviation fuel and ethanol mixed droplets prepared with different volume ratios in the combustion cycle,put forward two calculation models of micro-explosion intensity,and analyze the micro-explosion intensity characteristics of binary and ternary mixed droplets.The major contents are summarized as follows;Firstly,this paper propose a method to measure the volume of micro-droplet,and three kinds of droplets with different volumes are produced by this method.Beised on the experimental platform of the common rail heating system under constant telq)erature,this paper study the micro-explosion characteristics of the mixed droplets of biodiesel and ethanol in the combustion cycle,and analyze the flame characteristics,ignition delay time,micro-explosion delay time and burnout time of biodiesel and ethanol in different proportions.In addition,this paper put forward the calculation formula of micro-explosion intensity based on the expansion time of mixed droplets,and analyze the reasons why different intensities of mixed droplets occur when the phenomena of expansion,ejection and micro-explosion occur.Secondly,relying on the common rail heating system under constant temperature,the paper comparatively study the micro-explosion characteristics of RP-3/ethanol and biodiesel/ethanol mixed droplets in the combustion cycle,and explain the conditions of ejection and micro-explosion.Based on the analysis of the combustion sequence diagram of the mixed droplets,it is found that the BD 60%mixed droplet have a higher intensity micro-explosion during combustion,while the RP-3 60%mixed droplets only have an ejection phenonenon during combustion.By adjusting the equation of micro-explosion intensity,the revised calculation formula of micro-explosion intensity is established.Through the analysis of binary mixed droplets,it is found that the calculated value of micro-explosion intensity can distinguish the two combustion phenomena of micro-explosion and ejection.Thirdly,the combustion characteristics of biodiesel,aviation fuel and ethanol mixed fuel are studied by two experimental platforms.According to the phenomenon of mixed droplets after micro-explosion,a new calculation model of micro-explosion intensity is established,and the micro-explosion intensity of 10 kinds of mixed droplets is calculated.Micro-explosions of different intensities are classified into different grades.Furthermore,the micro-explosion characteristics of BD60E40 droplet and BD60R10E30 droplet are compared and analyzed based on the micro-explosion intensity calculation model.Finally,the micro-explosion characteristics of biodiesel and ethanol mixed droplets at different temperatures and different oxygen concentrations are studied using a tubular furnace experimental platform.At 300?,BD60E40 droplets do not explode slightly during heating.However,obvious micro-explosion occur at 400? and 500?.Under the conditions of oxygen concentration of 0%and 30%,the BD60E40 droplets all have secondary micro-explosions,and the secondaiy micro-explosions all occur in free fall.When the oxygen concentration was 50%and 100%,the BD60E40 droplet is observed to bum.The ignition phenomenon first occur around the ejected ethanol vapor above the droplet,and the burning ethanol vapor ignite the mixed droplet.This phenomenon is of great significance for the start-up of an aircraft engine when it stopped in the air.