Enhancement of subcooled boiling in confined space using ultrasonic waves
Enhancement of subcooled boiling in confined space using ultrasonic waves
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DOI：
10.1016/j.ces.2020.115751
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发表时间：
2020-09
影响因子：
4.7
通讯作者：
Xiao Li;Jiguo Tang;Licheng Sun;Jia Li;J. Bao;Hongli Liu
中科院分区：
文献类型：
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作者：
Xiao Li;Jiguo Tang;Licheng Sun;Jia Li;J. Bao;Hongli Liu
研究了超声波对有限空间内从核态沸腾到膜态沸腾或微泡喷射沸腾的传热和汽泡行为的影响。实验结果表明，在超声场中，受限空间的临界热流密度提高了4倍。在过渡沸腾区，在非受限空间内，过冷度超过20 K时会出现MEB，而在受限空间内，即使过冷度为60 K时也不会出现MEB。可视化显示，一个大的聚结气泡陷阱在有限的空间，这抑制了液体供应到加热表面上。应用超声波将在过冷度超过25 K时重新引入MEB。通过对有、无超声波作用下受限空间内微气泡的对比分析，揭示了由微气泡的剧烈振荡和汽膜坍塌引起的强对流对微气泡的传热起着重要的作用。
Effects of ultrasonic waves on heat transfer and bubble behavior spanning from nucleate boiling to film boiling or microbubble emission boiling (MEB) in a confined space were investigated. Experimental results show that critical heat flux in the confined space is increased by four times in the ultrasonic field. In transition boiling regime, MEB occurs at subcooling over 20 K in the unconfined space, however it cannot be observed in the confined space even for a subcooling of 60 K. Visualizations show that a large coalesced bubble traps in the confined space, which inhibits the supply of liquid onto the heating surface. Applying the ultrasound will reintroduce MEB at subcooling over 25 K. A comparison of MEB in the confined space with and without the ultrasound reveals that the strong bulk convection introduced by the violent oscillation and collapse of vapor film plays an important role in heat transfer of MEB.