Formation Mechanism and Characteristics of a Liquid Microlayer in Microchannel Boiling System
Formation Mechanism and Characteristics of a Liquid Microlayer in Microchannel Boiling System
复制标题
微通道沸腾系统液体微层的形成机理及特征
DOI：
10.1115/1.4002365
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发表时间：
2010
影响因子：
--
通讯作者：
Y. Kashiwabara
中科院分区：
文献类型：
--
作者：
Yaohua Zhang;Y. Utaka;Y. Kashiwabara
使用激光消光法进行实验，以测量通过在间隙尺寸为0.5 mm、0.3 mm和0.15 mm的微通道中生长扁平气泡而形成的液膜的厚度。水、乙醇和甲苯被用作测试流体。还使用高速摄像机来同时测量气泡生长过程。实验结果表明，气泡前沿速度和差距大小决定了初始微层厚度。微层厚度相对于界面速度的变化趋势分为两个区域：I区，速度较小，厚度随速度的增加而线性增加; II区，厚度几乎不变或随速度的增加而略有减小。此外，一个无量纲的相关性研究的影响，测试材料和间隙尺寸上的微层厚度。对结果的分析表明，两个区域的边界对应于约110的Weber数，并且在Weber数小于110的区域中，对于ρ 0.62 ν 0.42 σ -0.62值相对较小的液体，微层的厚度较薄。然而，对于韦伯数大于110的区域，液体的运动粘度越小，微层变得越薄。
Experiments were performed using the laser extinction method to measure the thickness of the liquid film formed by growing flattened bubbles in a microchannel for gap sizes of 0.5 mm, 0.3 mm, and 0.15 mm. Water, ethanol, and toluene were used as test fluids. A high-speed camera was also used to simultaneously measure the bubble growth process. It was confirmed that the gap size and bubble forefront velocity determined the initial microlayer thickness. The variation trend of the microlayer thickness relative to the velocity of the interface was divided into two regions: region I, where the velocity is small and the thickness increases linearly with increasing velocity, and region II, where the thickness is almost constant or decreased slightly with increasing velocity. Furthermore, a nondimensional correlation for investigating the effects of test materials and gap sizes on microlayer thickness is presented. An analysis of the results showed that the boundaries of the two regions correspond to a Weber number of approximately 110, and in the region where the Weber number was smaller than 110, the thickness of the microlayer was thinner for the liquid whose value of ρ 0.62 ν 0.42 σ -0.62 was relatively small. However, for the region where Weber number was larger than 110, the smaller the kinematic viscosity of the liquid, the thinner the microlayer became.