Nam Hyeon Taek, Cho Hyung Hee, Lee Seungro, Lee Donghwi
Department of Mechanical Engineering, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea.
Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea.
ACS Appl Mater Interfaces. 2024 Jul 3;16(26):34313-34325. doi: 10.1021/acsami.4c04114. Epub 2024 Jun 22.
Boiling heat transfer has a high thermal efficiency by latent heat absorption, which makes it an attractive process for cooling electronic device chips. Critical heat flux (CHF), the maximum heat flux, is a crucial factor determining the operating range of the boiling applications. The CHF can be enhanced by improving the fluid supply to the boiling surface. Herein, micropillar interfacial surfaces have been proposed to increase the CHF by increasing the rewetting flow, which determines the fluid-supply capacity near the bubble contact line. A state-of-art two-phase particle image velocimetry (two-phase PIV) technique is introduced for rewetting flow measurement on micropillar structures (MPSs) to analyze the CHF-enhancement mechanism. The two-phase PIV visualization setup offers high spatial (∼120 μm) and temporal (∼2000 Hz) resolutions for measuring rewetting flow during bubble growth. The MPS samples exhibit enhanced CHF and rewetting flows compared to those on a plain surface. The roughest case, D04G10 sample, had a CHF of 164 W/cm, 1.84 times higher than that of the plain surface. The D04G10 sample also recorded the highest rewetting velocity of 0.311 m/s, 4.7 times higher than that of the plain surface. The comparison between the rewetting flow and wicking performance shows that wicking-induced flow accounted for a substantial part (∼17%) of the rewetting flow and contributed significantly to the CHF enhancement owing to large rewetting flow by delaying vapor-film formation. Based on these findings, a new CHF model suggested by introducing the rewetting parameter shows a high CHF prediction accuracy of 94%.
沸腾传热通过潜热吸收具有很高的热效率，这使其成为冷却电子设备芯片的一个有吸引力的过程。临界热流密度（CHF），即最大热流密度，是决定沸腾应用操作范围的关键因素。通过改善向沸腾表面的流体供应可以提高CHF。在此，已提出微柱界面表面通过增加再润湿流来提高CHF，而再润湿流决定了气泡接触线附近的流体供应能力。引入了一种先进的两相粒子图像测速技术（两相PIV）来测量微柱结构（MPS）上的再润湿流，以分析CHF增强机制。两相PIV可视化装置为测量气泡生长过程中的再润湿流提供了高空间分辨率（约120μm）和高时间分辨率（约2000Hz）。与平面表面相比，MPS样品表现出增强的CHF和再润湿流。最粗糙的情况，即D04G10样品，CHF为164W/cm²，比平面表面高1.84倍。D04G10样品还记录到最高再润湿速度为0.311m/s，比平面表面高4.7倍。再润湿流与毛细作用性能的比较表明，毛细作用诱导的流占再润湿流的很大一部分（约17%），并且由于延迟汽膜形成导致再润湿流较大，对CHF增强有显著贡献。基于这些发现，通过引入再润湿参数提出的新CHF模型显示出94%的高CHF预测准确率。
