摘要
燃用甲醇可使柴油机实现高效清洁燃烧,燃料的蒸发特性对燃料的混合、着火、燃烧过程影响显著。甲醇十六烷值较低,着火困难,添加正庚烷可提高甲醇燃料的十六烷值。搭建了液滴蒸发试验装置,采用单液滴挂滴测量方法,使用高速摄像机拍摄液滴蒸发图像,基于图像处理技术研究了正庚烷-甲醇液滴的蒸发过程。分析不同正庚烷掺混体积比(0、5%、10%、15%)和环境温度(100~500℃)对液滴蒸发特性的影响。结果表明,正庚烷-甲醇燃料液滴的蒸发特性遵循D^(2)定律,即液滴直径D与液滴初始直径D_(0)比值的平方(D/D_(0))^(2)与蒸发时间呈线性关系。液滴相对面积随时间变化近似为一条斜率为负的直线。掺混体积比一定时,液滴蒸发速率随温度增加而增加。当温度从100℃增至500℃后,正庚烷掺混体积比0、5%、10%和15%的液滴单位面积蒸发速率分别增加了543%、639%、896%、556%。温度一定时,不同正庚烷添加剂掺混体积比的甲醇液滴蒸发的变化趋势基本相同。与纯甲醇相比,除200、300℃外,掺混体积比5%的正庚烷使液滴蒸发时间延长。100℃时,随正庚烷掺混体积比增加,液滴蒸发时间缩短;200℃时,随正庚烷掺混体积比增加,液滴蒸发时间延长;其余试验温度下,随正庚烷掺混体积比增加,液滴蒸发时间先延长后缩短。其中,在200、300、400、500℃,正庚烷掺混体积比从5%增至15%后,液滴蒸发时间分别延长了53.9%、17.1%、47.5%、53.1%。
Methanol fueling can make diesel engine achieve efficient and clean combustion.The evaporative properties of the fuel have a significant effect on the mixing,ignition and combustion process.Methanol has a low cetane number,which makes ignition difficult.The cetane number of methanol fuel can be increased by the addition of n-heptane.the droplet evaporation process of n-heptane methanol droplet was studied based on image processing technology by using the single droplet hanging measurement method and high-speed camera to capture the droplet evaporation image.The effects of different n-heptane blending volume ratios(0,5%,10%,15%)and ambient temperatures(100-500℃)on the evaporation characteristics of droplets were analyzed.The results show that the evaporation characteristics of n-heptane-methanol droplet followed the D^(2)law,which means that the square of the ratio of the droplet diameter D to the initial droplet diameter D_(0)((D/D_(0))^(2))is linearly related to the evaporation time.The trend of the relative area of the droplets with time is approximated as a straight line with a negative slope.The evaporation rate of droplets increases with the increase of temperature when the mixing ratio is fixed.The evaporation rates per unit area of droplets is increased by 543%,639%,896%,and 556%for 0,5%,10%,and 15%n-heptane blending ratios,respectively,when the temperature is increased from 100℃to 500℃.The evaporation trends of methanol droplets with different n-heptane additive blending ratios are basically the same when the temperature is certain.Compared with pure methanol,5%volume ratio of n-heptane prolongs the evaporation time of droplets except at 200 and 300℃.At 100℃,the droplet evaporation time is shortened with the increase of n-heptane blending ratio,while prolonged at 200℃.At the rest of the test temperatures,the droplet evaporation time is prolonged and then decreased with the increase of n-heptane blending ratio.At 200,300,400 and 500℃,the droplet evaporation time is prolonged by 53.9%,17.1%,47
作者
张美娟
魏衍举
张启霞
陈晟闽
ZHANG Meijuan;WEI Yanju;ZHANG Qixia;CHEN Shengmin(School of Automotive and Traffic,Wuxi Institute of Technology,Wuxi 214121,China;School of Automobile&Traffic Engineering,Jiangsu University,Zhenjiang 212013,China;School of Energy and Power Engineering,Xi′an Jiaotong University,Xi′an 710049,China)
出处
《洁净煤技术》
CAS
北大核心
2022年第12期51-58,共8页
Clean Coal Technology
基金
国家自然科学基金资助项目(52176128,91741110,51776089)
陕西省重点研发计划资助项目(No.2019ZDLGY15-10)
江苏省高等职业院校专业带头人高端研修资助项目(2019GRFX111)
江苏省高校自然科学研究面上资助项目(17KJD470004)
江苏高校“青蓝工程”资助项目。
关键词
柴油机
清洁燃料
甲醇
正庚烷
液滴
蒸发特性
diesel engine
clean fuels
methanol
n-heptane
droplet
evaporation characteristics
