Zhong Junjie, Riordon Jason, Zandavi Seyed Hadi, Xu Yi, Persad Aaron H, Mostowfi Farshid, Sinton David
Department of Mechanical and Industrial Engineering, University of Toronto , Toronto, Ontario M5S 3G8, Canada.
Department of Mechanical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
J Phys Chem Lett. 2018 Feb 1;9(3):497-503. doi: 10.1021/acs.jpclett.7b03003. Epub 2018 Jan 16.
Condensation on the nanoscale is essential to understand many natural and synthetic systems relevant to water, air, and energy. Despite its importance, the underlying physics of condensation initiation and propagation remain largely unknown at sub-10 nm, mainly due to the challenges of controlling and probing such small systems. Here we study the condensation of n-propane down to 8 nm confinement in a nanofluidic system, distinct from previous studies at ∼100 nm. The condensation initiates significantly earlier in the 8 nm channels, and it initiates from the entrance, in contrast to channels just 10 times larger. The condensate propagation is observed to be governed by two liquid-vapor interfaces with an interplay between film and bridging effects. We model the experimental results using classical theories and find good agreement, demonstrating that this 8 nm nonpolar fluid system can be treated as a continuum from a thermodynamic perspective, despite having only 10-20 molecular layers.
纳米尺度上的凝结对于理解许多与水、空气和能源相关的自然和合成系统至关重要。尽管其很重要，但在小于10纳米的尺度下，凝结起始和传播的基础物理过程在很大程度上仍不为人知，这主要是由于控制和探测如此小的系统存在挑战。在这里，我们研究了正丙烷在纳米流体系统中受限至8纳米时的凝结情况，这与之前在约100纳米尺度下的研究不同。与仅10倍大的通道相比，凝结在8纳米通道中显著更早开始，并且从入口处开始。观察到凝结物的传播由两个液 - 气界面控制，存在膜效应和桥接效应之间的相互作用。我们使用经典理论对实验结果进行建模并发现吻合度良好，这表明尽管这个8纳米的非极性流体系统仅有10 - 20个分子层，但从热力学角度来看可以被视为连续介质。
