Evaporation from a free liquid surface
Evaporation from a free liquid surface
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DOI：
10.1016/j.ijheatmasstransfer.2014.02.010
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发表时间：
2014-06
影响因子：
5.2
通讯作者：
Amal Lotfi;J. Vrabec;J. Fischer
中科院分区：
文献类型：
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作者：
Amal Lotfi;J. Vrabec;J. Fischer
稳态蒸发从一个平面的液体表面到真空中建模的非平衡分子动力学模拟的Lennard-Jones流体。本文对低温T/Tc= 0.53、中温T/Tc= 0.65和高温T/Tc= 0.84的液体进行了研究，其中T为临界温度。给出了密度、动力学温度、组分区分、漂移速度、出流、入流和总粒子通量以及蒸发系数α的分布结果。此外，速度分布函数。模拟结果与动力学理论的结果进行了比较。主要调查结果如下：（a）对于低温，模拟得出了蒸汽密度和温度以及粒子通量的值，这证实了赫兹关于出射的半边麦克斯韦的假设，即α= 1。(b)对于所有的温度，密度分布没有显着改变在液体中，并在界面上的平衡相比。(c)对于中温和高温，液体中的动力学温度已经有所降低，界面中的动力学温度降低更多，这导致颗粒通量低于赫兹假设的值，因此α随温度降低。最后，给出了一个简单的关联式，用以估计α作为T/Tc的函数。
Steady state evaporation from a planar liquid surface into vacuum is modelled by non-equilibrium molecular dynamics simulations of a Lennard-Jones fluid. Studies are made for liquids at a low temperatureT/Tc= 0.53, a medium temperatureT/Tc= 0.65 and a high temperatureT/Tc= 0.84, whereTcis the critical temperature. Results are given for the profiles of density, kinetic temperature, distinguishing between its components, and drift velocity, for the outgoing, incoming and total particle flux as well as for the evaporation coefficientα. Moreover, velocity distribution functions are shown. The simulation results are compared with those from kinetic theory. The key findings are: (a) For the low temperature, the simulations yield values for the vapour density and temperature as well as for the particle flux which confirm the assumption of Hertz about an outgoing half-sided Maxwellian which impliesα= 1. (b) For all temperatures, the density profiles do not change significantly in the liquid and in the interface in comparison with equilibrium. (c) For the medium and high temperatures, the kinetic temperatures somewhat decrease already in the liquid and more in the interface which leads to a lower particle flux than assumed by Hertz and henceαdecreases with temperature. Finally, a simple correlation is given to estimateαas a function ofT/Tc.