Channel height effects on forced-convection boiling and critical heat flux from a linear array of discrete heat sources
Channel height effects on forced-convection boiling and critical heat flux from a linear array of discrete heat sources
复制标题
通道高度对离散热源线性阵列的强制对流沸腾和临界热通量的影响
DOI：
10.1016/0017-9310(92)90190-4
复制
发表时间：
1992
影响因子：
5.2
通讯作者：
I. Mudawar
中科院分区：
文献类型：
--
作者：
T. Willingham;I. Mudawar
由于文献中对通道高度对矩形通道内强制对流沸腾和临界热流密度(CHF)的影响缺乏了解，在通道高度分别为2、5和10 mm的情况下，用FC-72在1.36bar上进行了实验。研究了模拟微电子芯片的9个离散热源组成的线性阵列在13~40 0 cm S−1和3~36°C温度范围内的沸腾换热。这些实验的独特之处在于，热流集中在与芯片宽度相对应的通道周长的一小部分上，而未加热的流体在芯片的两边流动。在2 mm通道中的流动显示显示，近饱和流动中的气泡横跨整个通道宽度，速度和/或过冷度的增加减少了气泡层的横向扩展；另一方面，5 mm和10 mm通道中的气泡主要局限在恰好位于切屑上方的区域。利用漂移流模型，建立了确定过冷沸腾空泡率的分析方法。实验数据由空泡率预测和流动显示支持，表明存在一个强迫对流CHF最大的最佳通道高度。对于相同的流速，本研究中的最大CHF值在5 mm流道内获得。
Due to the lack of understanding in the literature of channel height effects on forced-convection boiling and critical heat flux (CHF) in rectangular channels, experiments were performed with FC-72 at 1.36 bar for channel heights of 2, 5, and 10 mm. Boiling heat transfer from a linear array of nine discrete heat sources simulating microelectronic chips was investigated for velocity and liquid subcooling ranges of 13–400 cm s−1and 3–36°C, respectively. Unique to these experiments was the concentration of heat flux on a fraction of the channel perimeter corresponding to the width of the chip, with unheated fluid flowing on either side of the chips. Flow visualization in the 2 mm channel revealed that bubbles in near-saturated flow spanned the entire width of the channel, and increases in velocity and/or subcooling reduced the lateral spread of the bubble layer; on the other hand, bubbles in the 5 and 10 mm channels were primarily confined to the area just above the chips. Using the drift-flux model, an analysis for determining the void fraction in subcooled boiling was developed. Experimental data supported by void fraction predictions and flow visualization suggest the existence of an optimal channel height for which forced-convection CHF is a maximum. For equal flow velocities, maximum CHF values in the present study were obtained with the 5 mm channel.