Effect of Temperature and Ethanol on Evaporation Characteristics of Jatropha Oil Methyl Ester
To investigate the effects of temperature and ethanol on the evaporation characteristics of jatropha oil methyl ester(JME)droplets,the evaporation process of JME droplets(JME,JME-E10 and JME-E50)with different amounts of ethanol(0％,10％and 50％)was studied at the temperatures of 973 and 1 073 K by droplet experiment.The effects of temperature and ethanol content on the normalized square diameter of single fuel droplet evaporation were analyzed.The results showed that the evaporation characteristics of fuel droplets at 973 K were significantly different from those at 1 073 K.The evaporation characteristic curve cannot be simply divided into three stages:transient heating stage,fluctuating evaporation stage and equilibrium evaporation stage.Both ambient temperature and ethanol concentration affected the evaporation of JME bio-oil to a certain extent.Under high temperature conditions,the volatile components contained in the droplet form bubbles,which caused the droplet expand and underwent micro-explosion.The higher ambient temperature of a single droplet,the shorter evaporation time.This was because the expansion rate of the droplet was greater than the evaporation rate before the sudden change,and there were bubbles in the droplet until the bubble became larger.As the pressure was greater than the ambient pressure,it moved to the surface of the droplet,and when the bubble reached the maximum,a micro-explosion occurred.At 973 and 1 073 K,JME was in equilibrium evaporation for a period of time,which conformed to the D2 law,while JME-E10 and JME-E50 were different in that their droplet diameter fluctuated greatly during the evaporation stage.The evaporation process also occurred in polymerization reaction.The average evaporation rate of droplets increased with increasing temperature,and the evaporation rate of JME-E50 was the largest at 1 073 K.The three fuels evaporated at different temperatures and eventually had a small residue owing to the polymerization of the unsaturated components to form high molecular polymers.
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