Abstract In this paper, the boiling vaporization and breakup of single droplets of n-butanol, n-hexadecane and their binary mixtures with 10-50 w.t.% n-butanol have been studied. The experiments of droplet evaporation with an elevated ambient temperature range of 537-609 K were conducted through the pendant drop method and high-speed camera technology. The mathematical method was also proposed to predict the heterogeneous superheat limit and nucleation rate within the droplet. The experimental results indicate that mono-component droplets only go through the transient heating and stable evaporation phases. While for bi-component droplets, the characteristics show strong two-phase flow instability. With increasing n-butanol concentration or ambient temperature, the heterogeneous nucleation will occur inside the blended droplet, which experiences fluctuation evaporation between the transient heating and stable evaporation phases. The droplet vaporization characteristics gradually change from normal evaporation to partial rupture or passive breakup and then to micro explosion which reduces the droplet lifetime considerably. The novelty of this work is that various ambient temperature conditions and compositions are adopted to study the droplet evaporation to identify the conditions that favor flash boiling, and a new analytical model of heterogeneous nucleation is proposed, which can be used to estimate the temperature at the instant of bubble nucleation.

中文翻译：

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二元燃料液滴沸腾汽化及多模破碎的分析与实验研究

摘要 在本文中，研究了正丁醇、正十六烷及其与 10-50 wt% 正丁醇的二元混合物的单个液滴的沸腾汽化和破碎。通过悬滴法和高速相机技术在537-609 K的升高环境温度范围内进行液滴蒸发实验。还提出了数学方法来预测液滴内的异质过热极限和成核率。实验结果表明单组分液滴仅经历瞬态加热和稳定蒸发阶段。而对于双组分液滴，其特性表现出强烈的两相流动不稳定性。随着正丁醇浓度或环境温度的增加，混合液滴内部会发生异相成核，在瞬态加热阶段和稳定蒸发阶段之间经历波动蒸发。液滴汽化特性逐渐从正常蒸发转变为部分破裂或被动破裂，然后是微爆炸，这大大降低了液滴的寿命。这项工作的新颖之处在于采用各种环境温度条件和成分来研究液滴蒸发以确定有利于闪沸的条件，并提出了一种新的非均相成核分析模型，该模型可用于估计温度气泡成核的瞬间。液滴汽化特性逐渐从正常蒸发转变为部分破裂或被动破裂，然后是微爆炸，这大大降低了液滴的寿命。这项工作的新颖之处在于采用各种环境温度条件和成分来研究液滴蒸发以确定有利于闪沸的条件，并提出了一种新的非均相成核分析模型，该模型可用于估计温度气泡成核的瞬间。液滴汽化特性逐渐从正常蒸发转变为部分破裂或被动破裂，然后是微爆炸，这大大降低了液滴的寿命。这项工作的新颖之处在于采用各种环境温度条件和成分来研究液滴蒸发以确定有利于闪沸的条件，并提出了一种新的非均相成核分析模型，该模型可用于估计在气泡成核的瞬间。