Institute of Thermal Science and Technology, Shandong University, Jinan 250061, China.
Shandong Institute of Advanced Technology, Jinan 250100, China.
Langmuir. 2021 Dec 21;37(50):14744-14752. doi: 10.1021/acs.langmuir.1c02696. Epub 2021 Nov 23.
Flow condensation in nanochannels is a high-efficiency method to deal with increasingly higher heat flux from micro/nanoelectronic devices. Here, we study the flow condensation heat transfer characteristics of nanochannels with different nanopillar cross-sectional areas and heights using molecular dynamics simulation. Results show that two phases containing vapor in the middle of the channel and liquid near walls can be distinguished by obvious interfaces when the fluid is at a stable state. The condensation performance can be promoted by adding nanopillars. With the increase in nanopillar cross-sectional areas or heights, the time that the fluid spends to reach stability will be put off, while the condensation performance enhances. Different from the small enhancement of nanopillar cross-sectional areas, the condensation heat transfer performance improves significantly at a higher nanopillar height, which increases the heat transfer rates by 11.6 and 35.8% when heights are 6 and 8, respectively. The preeminent condensation heat transfer performance is ascribed to the fact that nanopillars with a higher height disturb the vapor-liquid interface and vapor region, which not only allows vapor atoms with strong Brownian motion to collide with nanopillar atoms directly but also increases deviations of vapor-liquid potential energy to facilitate condensation heat transfer in nanochannels.
在纳米通道中进行流动冷凝是处理来自微/纳米电子设备的日益增加的高热通量的高效方法。在这里，我们使用分子动力学模拟研究了具有不同纳米柱横截面积和高度的纳米通道中的流动冷凝传热特性。结果表明，当流体处于稳定状态时，中间含有蒸汽的两相和靠近壁面的液体可以通过明显的界面区分开来。通过添加纳米柱可以促进冷凝性能。随着纳米柱横截面积或高度的增加，流体达到稳定所需的时间将会推迟，而冷凝性能则会增强。与纳米柱横截面积的小增强不同，纳米柱高度的增加会显著提高冷凝传热性能，当高度分别为 6 和 8 时，传热速率分别提高了 11.6%和 35.8%。卓越的冷凝传热性能归因于具有更高高度的纳米柱会干扰蒸汽-液体界面和蒸汽区域，这不仅允许具有强布朗运动的蒸汽原子直接与纳米柱原子碰撞，而且还增加了蒸汽-液体位能的偏差，从而促进了纳米通道中的冷凝传热。
