On bubble dynamics in subcooled nucleate boiling on a platinum wire
On bubble dynamics in subcooled nucleate boiling on a platinum wire
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DOI：
10.1016/j.ijthermalsci.2018.11.007
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发表时间：
2019-03
影响因子：
4.5
通讯作者：
A. Ozbey;M. Karimzadehkhouei;K. Sefiane;A. Koşar;J. Christy
中科院分区：
文献类型：
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作者：
A. Ozbey;M. Karimzadehkhouei;K. Sefiane;A. Koşar;J. Christy
虽然人们对沸腾现象给予了很大的关注，但由于其复杂和虚幻的性质，其潜在的物理和机制仍未完全理解。本文以直径为250 μm的铂丝为实验对象，研究了去离子水在体积温度为30 °C和常压下的过冷池沸腾过程，从核沸腾（ONB）点开始，到更高的热流密度。利用高速摄像系统进行可视化。记录了气泡生长、迁移、合并、跳跃和脱离的图像。对这些事件分别进行了调查，并进行了全面的讨论。利用高速相机图像分析了表面张力、气泡-气泡相互作用、成核点-气泡相互作用、马兰戈尼对流和气泡内不可冷凝气体积聚等重要参数。较低的外加热流导致气泡从成核位置成核，气泡缓慢生长到一定直径，并准备沿线材迁移。热通量的增大使气泡的生长速度加快，且由于温度梯度的增大和成核位置附近温度场的扰动，有利于气泡的聚并、跳跃和分离现象的发生。另一个被考虑的重要机制是气泡内不可冷凝气体的动量，特别是当气泡尾部消失和气泡收缩而停止在不移动的气泡附近或在成核位置附近时。
While much attention has been given to the phenomenon of boiling, the underlying physics and mechanisms are still not fully understood due to its complicated and illusive nature. In this study, an experimental investigation of subcooled pool boiling of de-ionized (DI) water, at a bulk temperature of 30 °C and atmospheric pressure, was performed on a platinum wire with a diameter of 250 μm, starting from the onset of nucleate boiling (ONB) point and rising to higher heat fluxes. A high speed camera system was utilized for visualization. Images of bubbles growth, migration, coalescence, leaping and detachment were recorded. Each of these events was investigated separately, and a comprehensive discussion undertaken. High speed camera images were analyzed by taking the most important parameters, such as surface tension, bubble-bubble interactions, nucleation site-bubble interactions, Marangoni convection and accumulation of non-condensable gases inside the bubbles. Lower applied heat fluxes led to bubble nucleation from the nucleation sites and slow growth of bubbles to a certain diameter, which were ready to migrate along the wire. Increasing the heat flux made the bubbles grow faster and favored coalescence, leaping and detaching that be observed one after another due to an increase in the temperature gradient and perturbation of the temperature field near the nucleation sites. Another important mechanism considered was the momentum of the non-condensable gases inside the bubbles, especially while the bubble tail disappeared and the bubble shrank whilst stopping near an immobile bubble or near the nucleation sites.