Simultaneous laser-induced fluorescence, particle image velocimetry and infrared thermography for the investigation of the flow and heat transfer characteristics of nucleating vapour bubbles
Simultaneous laser-induced fluorescence, particle image velocimetry and infrared thermography for the investigation of the flow and heat transfer characteristics of nucleating vapour bubbles
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DOI：
10.1016/j.ijheatmasstransfer.2022.122525
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发表时间：
2022-01-18
影响因子：
5.2
通讯作者：
Bucci, M.
中科院分区：
文献类型：
--
作者：
Voulgaropoulos, V.;Aguiar, G. M.;Bucci, M.
沸腾是一种有效的排热过程，用于许多技术应用中的热交换和热管理目的，从微电子设备到核反应堆的规模。然而，在这个过程中涉及的物理机制尚未完全理解，由于复杂性，从许多相互作用的基础子过程中涉及的成核，生长和分离的过程中发生的气泡。在这里，我们提出了一种先进的方法的基础上相结合，同步高速红外（IR）测温，比率双色激光诱导荧光（2cLIF）和粒子图像测速（PIV），沿着样品的实验结果在去离子水中进行的调查，旨在阐明参与气泡的生命周期的机制。红外测温是用来测量随时间变化的二维温度和热流分布的沸腾表面，和2cLIF是用来测量随时间变化的温度场在一个垂直的平面上，在液相周围的发展气泡。此外，PIV用于测量气泡周围的速度场，与2cLIF在同一平面内。调查揭示，并使我们能够量化的基本传热方面，如三重接触线蒸发的气泡生长过程中的贡献，近壁过热液体层的动态，气泡生长和离开产生的混合效果，周围的气泡对流效应，淬火传热。具体来说，我们观察到，在我们的实验中，随着气泡的缓慢增长，微层不会形成，并且在固-液-汽接触线处的蒸发贡献了传递到气泡的总热量的约三分之一。我们还观察到，当气泡离开沸腾表面时，重新润湿气泡底部干燥点的流体来自与气泡相邻的近壁过热热边界层，即，它比主体中的流体更热。我们证实了这一发现，通过建模淬火传热阶段作为一个瞬态传导过程。(c)2022爱思唯尔有限公司保留所有权利。
Boiling is an effective heat removal process, used for heat exchange and thermal management purposes in many technological applications, from the scale of microelectronic devices to nuclear reactors. However, the physical mechanisms involved in this process are not fully understood yet due to the complexity that arises from the many interacting underlying sub-processes involved in the nucleation, growth and detachment of bubbles that occur during the process. Here, we present an advanced methodology based on combined, synchronized high-speed infrared (IR) thermometry, ratiometric two-colour laser-induced fluorescence (2cLIF) and particle image velocimetry (PIV), along with sample results of an experimental investigation conducted in deionized water, aimed at elucidating the mechanisms involved in the bubble lifecycle. IR thermometry is used to measure the time-dependent 2-D temperature and heat flux distributions over a boiling surface, and 2cLIF is used to measure the time-dependent temperature-field in a vertical plane, in the liquid phase around developing bubbles. Furthermore, PIV is used to measure the velocity fields around the bubbles, in the same plane as 2cLIF. The investigation reveals and allows us to quantify fundamental heat transfer aspects such as the contribution of triple contact line evaporation to the bubble growth process, the dynamics of the near-wall superheated liquid layer, the mixing effect produced by bubble growth and departure, convection effects around the bubble, and quenching heat transfer. Specifically, we observe that, in our experiment, with slowly growing bubbles, the microlayer does not form, and the evaporation at the solid-liquid-vapour contact line contributes to approximately one third of the total heat transferred to the bubble. We also observed that the fluid that rewets the dry spot at the bubble base, as the bubble departs from the boiling surface, comes from the near-wall superheated thermal boundary layer adjacent to the bubble, i.e., it is warmer than the fluid in the bulk. We confirm this finding by modelling this quenching heat transfer phase as a transient conduction process. (c) 2022 Elsevier Ltd. All rights reserved.