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首页> 外文期刊>International Journal of Heat and Mass Transfer >Thermal transients during the evaporation of a spherical liquid drop
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Thermal transients during the evaporation of a spherical liquid drop

机译：球形液滴蒸发过程中的热瞬变

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摘要

This work is centered upon the thermal transients taking place during the evaporation of a spherical drop of a pure liquid suspended in a gaseous environment. Based on mass and energy conservation equations, a so-called complete model is developed considering quasi-steady diffusive and Stefan convective transports in the non-isothermal gas phase, and unsteady conduction in the liquid drop. A simplified version of the complete model, the so-called quasi-homogeneous model, is developed using an asymptotic analysis in the limit of small thermal homogenization time in the drop compared to the total drop evaporation time. The models enable highlighting the role of two dimensionless numbers, R and H, characterizing the two thermal transients of the problem: the thermal relaxation transient of the drop interfacial temperature and the thermal homogenization transient of the drop. The values of these two dimensionless numbers are provided for several liquids and their dependence on the evaporation conditions is discussed. It is shown that, when an accurate evaluation of the drop evaporation time is required by the considered application, the use of a fully quasi-steady model should be restricted to systems presenting small values of R compared to one (at least an order of magnitude smaller) and H ＜ 1. For other systems, it appears necessary to use the complete model or the quasi-homogeneous model. A simple formula is proposed to evaluate the relative difference between the drop evaporation times predicted by the complete model and by the fully quasi-steady model. When an accurate evaluation of the time evolution of the drop temperature field is required by the considered application, it appears to be necessary to use the complete model, whatever the system considered in this work. Indeed, the thermal transients can generally take an important part of the drop evaporation time and large temperature gradients can develop in the drop. The use of the complete model reveals that three different types of dynamics can be observed when a drop evaporates, depending on the relative values of three temperatures: the initial drop temperature, the dew point temperature of the gas far from the drop and the established interfacial temperature (i.e. the drop interfacial temperature calculated using a fully quasi-steady model).
机译：这项工作集中在悬浮在气态环境中的纯液体的球形液滴蒸发过程中发生的热瞬变上。基于质量和能量守恒方程，考虑到非等温气相中的准稳态扩散和Stefan对流输运以及液滴中的非稳态传导，开发了一个所谓的完整模型。完整模型的简化版本，即所谓的准均质模型，是使用渐近分析开发的，与总的液滴蒸发时间相比，液滴的热均质时间短，因此需要限制。这些模型可以突出显示两个无因次数R和H的作用，以表征问题的两个热瞬态：液滴界面温度的热弛豫瞬态和液滴的热均质瞬态。为两种液体提供了这两个无量纲数的值，并讨论了它们对蒸发条件的依赖性。结果表明，当所考虑的应用要求对液滴蒸发时间进行准确评估时，应将完全准稳态模型的使用限制为与R相比具有较小R值（至少一个数量级）的系统。较小，且H ＜1。对于其他系统，似乎有必要使用完整模型或准均质模型。提出了一个简单的公式来评估完整模型和完全准稳态模型预测的液滴蒸发时间之间的相对差。当所考虑的应用需要对下落温度场的时间演变进行准确评估时，无论在此工作中考虑的系统是什么，都有必要使用完整的模型。实际上，热瞬变通常会占据液滴蒸发时间的重要部分，并且液滴中会形成较大的温度梯度。完整模型的使用揭示了当液滴蒸发时可以观察到三种不同类型的动力学，具体取决于三个温度的相对值：初始液滴温度，远离液滴的气体露点温度和已建立的界面温度（即使用完全拟稳态模型计算的液滴界面温度）。

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  • 来源
  • 作者

    P. Talbot; B. Sobac; A. Rednikov; P. Colinet; B. Haut;

  • 作者单位

    Universite libre de Bruxelles, TIPs (Transfers, Interfaces and Processes), C.P. 165/67, av. F.D. Roosevelt 50, 1050 Brussels, Belgium;

    Universite libre de Bruxelles, TIPs (Transfers, Interfaces and Processes), C.P. 165/67, av. F.D. Roosevelt 50, 1050 Brussels, Belgium;

    Universite libre de Bruxelles, TIPs (Transfers, Interfaces and Processes), C.P. 165/67, av. F.D. Roosevelt 50, 1050 Brussels, Belgium;

    Universite libre de Bruxelles, TIPs (Transfers, Interfaces and Processes), C.P. 165/67, av. F.D. Roosevelt 50, 1050 Brussels, Belgium;

    Universite libre de Bruxelles, TIPs (Transfers, Interfaces and Processes), C.P. 165/67, av. F.D. Roosevelt 50, 1050 Brussels, Belgium;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Drop; Evaporation; Thermal transients; Relaxation; Homogenization;

    机译：下降;蒸发;热瞬态;松弛;均质化;

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