ZHANG Meijuan;WEI Yanju;ZHANG Qixia;CHEN Shengmin;

• 1:School of Automotive and Traffic
• 2:Wuxi Institute of Technology
• 3:School of Automobile & Traffic Engineering
• 4:Jiangsu University

Abstract：

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%, 47.5% and 53.1% when the n-heptane blending volume ratio increases from 5% to 15%, respectively.

Key Words： diesel engine;clean fuels;methanol;n-heptane;droplet;evaporation characteristics

Abstract:

Keywords:

Foundation: 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

Authors: ZHANG Meijuan;WEI Yanju;ZHANG Qixia;CHEN Shengmin;

DOI: 10.13226/j.issn.1006-6772.21082001

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