Heat transfer and phase interface dynamics during impact and evaporation of subcooled impinging droplets on a heated surface
Heat transfer and phase interface dynamics during impact and evaporation of subcooled impinging droplets on a heated surface
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DOI：
10.1016/j.applthermaleng.2024.123152
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发表时间：
2024-04
影响因子：
6.4
通讯作者：
Md Tanbin Hasan Mondal;Md Shafayet Alam;Rifat Hossain;Arden L. Moore
中科院分区：
文献类型：
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作者：
Md Tanbin Hasan Mondal;Md Shafayet Alam;Rifat Hossain;Arden L. Moore
全面了解液滴撞击受热表面和随后蒸发过程中的传热机制和流体动力学对于改进传热模型、优化表面工程和最大化整体效率至关重要。这项工作展示了与传热机制相关的发现，并利用定制的MEMS器件，在多个冲击速度下，在一定的表面温度范围内同时跟踪过冷撞击液滴的移动接触线（MCL）。实验结果表明，液滴撞击引起的热流通量对表面温度的依赖性较弱，而蒸发引起的退去式MCL换热对表面温度的依赖性较强。测量还表明，当液滴撞击加热表面并蒸发时，该过程可以根据有效传热速率分为两个部分：初始传导主导的部分，然后是表面蒸发主导的另一部分。对于过冷的撞击液滴，发现振荡运动的影响可以忽略不计，这与过热状态不同；因此，进入液滴的热传导完全支配着第一段。结果还表明，撞击液滴固液界面的热流密度随撞击速度和表面温度的升高而增大。在过冷状态下，液滴撞击加热表面的垂直热流密度值比缓慢沉积的液滴高约1.6倍。此外，本研究量化了液滴内浮力和热毛细对流对整体传热的贡献。
A comprehensive understanding of heat transfer mechanisms and hydrodynamics during droplet impingement on a heated surface and subsequent evaporation is crucial for improving heat transfer models, optimizing surface engineering, and maximizing overall effectiveness. This work showcases findings related to heat transfer mechanisms and simultaneous tracking of the moving contact line (MCL) for subcooled impinging droplets across a range of surface temperatures, utilizing a custom MEMS device, at multiple impact velocities. Experimental results show that heat flux caused by droplet impingement has a weaker dependence on surface temperature than receding MCL heat transfer due to evaporation, which is significantly surface temperature dependent. The measurements also demonstrate that when a droplet impacts a heated surface and evaporates, the process can be divided into two segments based on the effective heat transfer rate: an initial conduction-dominated segment followed by another segment dominated by surface evaporation. For subcooled impinging droplets, the effect of oscillatory motion is found to be negligible, unlike in a superheated regime; hence, heat conduction into the droplet entirely governs the first segment. Results also show that heat flux at the solid-liquid interface of an impinging droplet increases with the rise of either impact velocity or surface temperature. In the subcooled regime, droplets impacting a heated surface have approximately 1.6 times higher vertical heat flux values than gently deposited droplets. Furthermore, this study quantifies the contributions of buoyancy and thermocapillary convection within the droplet to the overall heat transfer.