CIESC Journal ›› 2015, Vol. 66 ›› Issue (2): 703-708.DOI: 10.11949/j.issn.0438-1157.20140745

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Influence of substrate thickness on temperature distribution along surface of drying droplets

ZHANG Kai, WANG Yilin, XU Xuefeng   

  1. School of Technology, Beijing Forestry University, Beijing 100083, China
  • Received:2014-05-20 Revised:2014-09-18 Online:2015-02-05 Published:2015-02-05
  • Supported by:

    supported by the National Natural Science Foundation of China (51275050), the Program for New Century Excellent Talents in University (NCET-12-0786) and the Specialized Research Fund for the Doctoral Program of Higher Education (20120014120017).

基底厚度对蒸发液滴表面温度分布的影响

张凯, 王依霖, 徐学锋   

  1. 北京林业大学工学院, 北京 100083
  • 通讯作者: 徐学锋
  • 基金资助:

    国家自然科学基金项目(51275050);教育部新世纪优秀人才支持计划项目(NCET-12-0786);高等学校博士学科点专项科研基金项目(20120014120017)。

Abstract:

The temperature distribution along the surface of drying droplet has significant influence on fluid flow and particle deposition of the droplet. Currently, the surface temperature distribution of the droplet is often studied by numerical methods. For drying droplets on finite thickness substrates, the effect of meshing on calculated surface temperature is discussed. Compared to the region near the droplet edge, mesh refinement in the central region of the droplet has negligible effect on numerical results. The influence of the size of mesh refinement region near the droplet edge on droplet surface temperature can also be neglected compared to the level of mesh refinement. By studying the effects of relative substrate thickness hR on droplet surface temperature, three different states with changing substrate thickness are found. (1) From center to edge, surface temperature increases monotonically. (2) From center to edge, surface temperature changes non-monotonically. (3) From center to edge, surface temperature decreases monotonically. The different patterns of droplet surface temperature can be explained by considering the combined effects of heat conduction path length and evaporative cooling. The surface temperature "phase diagram" on parameters (hR, q) with different relative thermal conductivities is obtained. The results will be helpful to understanding droplet evaporation and providing theoretical basis for evaporation induced self-assembly and ink jet printing.

Key words: droplet, evaporation, heat transfer, surface temperature distribution, numerical simulation

摘要:

蒸发液滴的表面温度分布对液滴的液体流动和颗粒沉积有着重要的影响。获得液滴表面温度目前主要采用数值计算方法。针对有限厚度基底上的蒸发液滴,分析了网格划分对液滴表面温度计算结果的影响。结果表明,相比于液滴边缘附近区域,液滴中心区域网格的细化对计算结果影响不大;而在接触线附近,相比于网格尺寸,网格细化区域大小对计算结果的影响也很小。利用数值方法研究了基底厚度对蒸发液滴表面温度分布特性的影响,发现随着基底厚度的改变液滴表面出现3种温度分布模式:(1)从液滴顶点到边缘处表面温度逐渐升高;(2)液滴表面温度非单调变化;(3)从液滴顶点到边缘处表面温度逐渐降低。考虑热传导路径长度和蒸发制冷的共同作用,对不同表面温度分布模式进行了解释,并获得了(hR,q)坐标平面上的表面温度分布模式相图。本文结果将有助于对液滴蒸发过程的理解,并为蒸发诱导自组装、喷墨印刷等技术提供理论依据。

关键词: 液滴, 蒸发, 传热, 表面温度分布, 数值模拟

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