Al-Kindi Ilyas, Babadagli Tayfun
7-203 Donadeo Innovation Centre for Engineering, University of Alberta, 9211-116 Street NW, Edmonton, Alberta T6G 1H9, Canada.
ACS Appl Mater Interfaces. 2021 Jun 16;13(23):27612-27621. doi: 10.1021/acsami.1c05503. Epub 2021 Jun 7.
The displacement characteristics of gas-liquid systems in capillary media under nonisothermal and nonisobaric conditions are controlled by capillarity as phase alteration (specifically vaporization) starts earlier in smaller (nano)capillaries compared to the larger ones. For an accurate modeling of these types of natural and engineered processes, this thermodynamically dictated displacement process should be well understood. With this aim, the capillarity effect on phase change and the displacement dynamics of hydrocarbon liquids in homogeneous and heterogenous silicate microfluidics chips was studied. It was observed that the boiling temperatures of pentane, a pentane-heptane mixture, and a pentane-heptane-octane mixture were 1.6-6.9% lower than bulk measurements due to confinement effects, and the early vaporization had a significant influence on the vapor displacement process. In homogeneous (uniform capillary pressure distribution) porous media, the consistency of capillary pressure resulted in a uniform and quicker propagation/displacement of vapor. However, in the media with variable capillary pressure (heterogeneous pore structure), the vapor's flow tended to take place nonuniformly along the system, thus leading to a major gas fingering and gas-flow restriction. The presence of other-heavier-components (liquid phase) in the porous medium developed an excessive barrier against the vapor's flow throughout the pore channels that was specifically caused by the viscous forces of the liquids. Moreover, it was observed that the existence of liquids with high boiling points contribute to slowing the vapor propagation of the lighter components, and the gas displacement becomes slower as the density and viscosity of the liquid-phase components increases.
在非等温非等压条件下，毛细管介质中气液系统的驱替特性受毛细作用控制，因为与较大的毛细管相比，较小（纳米）毛细管中的相变（特别是汽化）开始得更早。为了准确模拟这些自然和工程过程，需要深入理解这种由热力学决定的驱替过程。为此，研究了毛细作用对均相和非均相硅酸盐微流控芯片中相变以及烃类液体驱替动力学的影响。研究发现，由于受限效应，戊烷、戊烷 - 庚烷混合物以及戊烷 - 庚烷 - 辛烷混合物的沸点比体相测量值低1.6 - 6.9%，且早期汽化对蒸汽驱替过程有显著影响。在均相（毛细管压力分布均匀）多孔介质中，毛细管压力的一致性导致蒸汽均匀且更快地传播/驱替。然而，在毛细管压力可变（孔隙结构非均相）的介质中，蒸汽流倾向于沿系统不均匀地发生，从而导致严重的气窜和气流受限。多孔介质中其他较重组分（液相）的存在对蒸汽在整个孔隙通道中的流动形成了过大的阻碍，这是由液体的粘性力特别导致的。此外，研究还发现，高沸点液体的存在会导致较轻组分的蒸汽传播速度减慢，并且随着液相组分密度和粘度的增加，气体驱替变得更慢。
