Jaikumar Arvind, Kandlikar Satish G
Microsystems Engineering, Rochester Institute of Technology, 76 Lomb Memorial Drive, Rochester, NY, 14623, USA.
Mechanical Engineering, Rochester Institute of Technology, 76 Lomb Memorial Drive, Rochester, NY, 14623, USA.
Sci Rep. 2017 Nov 16;7(1):15691. doi: 10.1038/s41598-017-16035-8.
We demonstrate that the contact line (CL) motion on energetically heterogeneous solid surfaces occurs in a coupled fashion as against the traditional staggered stick-slip motion. Introducing chemical inhomogeneities at nanoscale induces a local change in dynamic contact angles which manifests as a smooth and continuous motion of the CL. Nanoscale chemically inhomogeneous surfaces comprising of gold, palladium and nickel were generated on copper substrates to demonstrate the underlying CL dynamics. The spatial variations of chemical constituents were mapped using elemental display scanning electron microscope images. Further, the coupled and stick-slip motion was confirmed for a sliding water droplet on these surfaces, and then used in studying the pool boiling bubble dynamics of a single bubble from nucleation to departure. The coupled motion was seen to increase the CL velocity thereby increasing the contribution from transient conduction heat transfer. Consequently, a ~2X increase in the boiling critical heat flux (CHF) was observed. Enhancing the pool boiling performance by introducing nanoscale surface features is an attractive approach in many applications and this work provides a framework and understanding of the CL motion induced through the chemical inhomogeneity effects.
我们证明，在能量异质的固体表面上，接触线（CL）的运动以耦合方式发生，这与传统的交错式粘滑运动不同。在纳米尺度引入化学不均匀性会导致动态接触角的局部变化，这表现为CL的平滑连续运动。在铜基板上生成了由金、钯和镍组成的纳米尺度化学不均匀表面，以展示潜在的CL动力学。使用元素显示扫描电子显微镜图像绘制化学成分的空间变化。此外，证实了这些表面上滑动水滴的耦合和粘滑运动，然后用于研究单个气泡从成核到脱离的池沸腾气泡动力学。观察到耦合运动会增加CL速度，从而增加瞬态传导热传递的贡献。因此，观察到沸腾临界热通量（CHF）增加了约2倍。通过引入纳米尺度表面特征来提高池沸腾性能在许多应用中是一种有吸引力的方法，这项工作提供了一个框架，并对通过化学不均匀性效应引起的CL运动有了理解。
