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Langmuir. 2016 May 10;32(18):4494-9. doi: 10.1021/acs.langmuir.6b01056. Epub 2016 Apr 26.
In materials with tiny, nanometer-scale pores, liquid condensation is shifted from the bulk saturation pressure observed at larger scales. This effect is called capillary condensation and can block pores, which has major consequences in hydrocarbon production, as well as in fuel cells, catalysis, and powder adhesion. In this study, high pressure nanofluidic condensation studies are performed using propane and carbon dioxide in a colloidal crystal packed bed. Direct visualization allows the extent of condensation to be observed, as well as inference of the pore geometry from Bragg diffraction. We show experimentally that capillary condensation depends on pore geometry and wettability because these factors determine the shape of the menisci that coalesce when pore filling occurs, contrary to the typical assumption that all pore structures can be modeled as cylindrical and perfectly wetting. We also observe capillary condensation at higher pressures than has been done previously, which is important because many applications involving this phenomenon occur well above atmospheric pressure, and there is little, if any, experimental validation of capillary condensation at such pressures, particularly with direct visualization.
在具有微小纳米级孔隙的材料中，液体冷凝会偏离在较大尺度下观察到的整体饱和压力。这种效应被称为毛细冷凝，它会堵塞孔隙，这在烃类生产、燃料电池、催化和粉末附着等方面有重大影响。在这项研究中，在胶体晶体填充床中使用丙烷和二氧化碳进行高压纳米流体制冷研究。直接可视化允许观察冷凝的程度，以及从布拉格衍射推断孔隙几何形状。我们通过实验表明，毛细冷凝取决于孔隙几何形状和润湿性，因为这些因素决定了孔填充时合并的弯月面的形状，这与典型的假设相反，即所有的孔隙结构都可以被建模为圆柱形和完全润湿的。我们还观察到高于以往研究的压力下的毛细冷凝，这很重要，因为许多涉及这种现象的应用都发生在高于大气压的环境中，而在这种压力下，特别是通过直接可视化，对毛细冷凝的实验验证很少，如果有的话。
