Effect of ambient temperature on the micro-explosion characteristics of soybean oil droplet: The phenomenon of evaporation induced vapor cloud

•Soybean oil droplet shows four-staged evaporation characteristics at high temperatures.•The micro-explosion strength increases with the increase of ambient temperature.•Evaporation induced vapor cloud was first observed at 973 K.•Homogenous and heterogeneous nucleation were observed at 873 K, 923 K...

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Bibliographic Details
Published in:International journal of heat and mass transfer 2019-08, Vol.139, p.736-746
Main Authors: Wang, Lintao, Wang, Jigang, Qiao, Xinqi, Ju, Dehao, Lin, Zhimin
Format: Article
Language:English
Subjects:
Ambient temperature
Atomizing
Droplet evaporation
Droplets
Evaporation
Evaporation rate
Explosions
Micro-explosion
Nucleation
Outflow
Soybean oil
Soybeans
Transient heating
Vapor cloud
Vapor clouds
Vegetable oils
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Summary:•Soybean oil droplet shows four-staged evaporation characteristics at high temperatures.•The micro-explosion strength increases with the increase of ambient temperature.•Evaporation induced vapor cloud was first observed at 973 K.•Homogenous and heterogeneous nucleation were observed at 873 K, 923 K and 973 K. Micro-explosion characteristics of soybean oil droplet were investigated using high speed backlight imaging technique at ambient temperature 873 K, 923 K and 973 K. Experimental results indicate that soybean oil droplet underwent transient heating phase, micro-explosion evaporation phase, equilibrium evaporation phase, and residue evaporation phase at all the studied temperatures. The evaporation rate of equilibrium evaporation phase is increased when the temperature increased. However, a decrease for the evaporation rate of residue evaporation phase. Homogeneous and heterogeneous nucleation are observed at all temperatures, homogeneous nucleation lead to strong micro-explosion and heterogeneous nucleation lead to weak micro-explosion. Moreover, micro-explosion strength increased when the ambient increased. It was found that the micro-explosion occurred at the end of droplet evaporation, this is one of the reasons for the poor atomization characteristics of bio-oil in the engine. More importantly, the evaporation induced vapor cloud is observed at 973 K, this is mainly due to the non-isothermal condensation caused by Stefan outflow.
ISSN:0017-9310
1879-2189
DOI:10.1016/j.ijheatmasstransfer.2019.04.038