Abstract
Droplets and rivulets over solid surfaces play an important role in a number of engineering applications. We use a Computational Fluid Dynamics model consisting in a smooth inclined plate to study the effect of the contact angle on the morphology, residence time and mass transfer into liquid rivulets. Measurements of the contact angle—using the sessile drop method—between aqueous monoethanolamine solutions and two commercial surfaces used for gas separation, are introduced as boundary condition. Reducing the contact angle from 60° to 20° flattens the rivulet, increasing the gas-liquid interface area by 85%. The cumulative residence time broadens, with an increase of 12% in τ10, and of 37% in τ90. There is consequently, a theoretical increase of 68% in the total mass transfer rate. A sensible design of the liquid-solid interaction is therefore crucial to good mass transfer performance.
Highlights
Rivulet flow appears in a number of practical problems such as industrial coating processes (Marshall and Wang, 2005), rainwind induced vibrations in cable-stayed bridges (Cheng et al, 2015), microfluidics (Herrada et al, 2015; Labib et al, 2011), heat exchangers (Hu et al, 2017; Sultanovicet al., 1997) and packed bed absorbers (Nawrocki and Chuang, 1996)
We study numerically the morphology, velocity field and residence time distribution of the rivulets which form over structured packings used for gas scrubbing, describing their impact on the mass transfer
We have studied numerically the effect of the contact angle on the morphology and residence time distribution of gravity-driven liquid rivulets, as well as analysed theoretically their effect on the absorption mass transfer
Summary
Rivulet flow appears in a number of practical problems such as industrial coating processes (Marshall and Wang, 2005), rainwind induced vibrations in cable-stayed bridges (Cheng et al, 2015), microfluidics (Herrada et al, 2015; Labib et al, 2011), heat exchangers (Hu et al, 2017; Sultanovicet al., 1997) and packed bed absorbers (Nawrocki and Chuang, 1996) In the latter for instance, deeper knowledge is needed on the liquid pattern formed over the packing, which is not a fully developed liquid film, but rivulets and droplets (Fitz et al, 1999; Aferka et al, 2011; Olujicand Jansen, 2015; Olujic , 2002; Brito et al, 1994; Bravo and Fair, 1982). In this work, to deepen in the cause of the beneficial effect that a greater spreading coefficient has on the absorption mass transfer into liquid structures formed on solid surfaces
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