Modeling nanofluid sessile drop evaporation

Gerken, William J.; Oehlschlaeger, Matthew A.

doi:10.1007/s00231-017-1986-7

Cited by 6 publications

(2 citation statements)

References 27 publications

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“…The evaporation and deposition of dispersed particles (commonly termed as the “coffee-stain” or “coffee-ring” effect) in pure fluids were initially studied by Deegan and co-workers − on a flat surface. Since then, numerous investigators have addressed this problem at ambient and elevated substrate temperatures for single-component fluids. ,− Moffat et al , observed that a nanofluid sessile droplet on a substrate exhibits a stick–slip behavior caused by nanoparticle aggregation near the triple contact line, which was found to be further dependent on the evaporation rate and effective thermal conductivity of droplets . Du and Deegan used numerical simulations of a two-dimensional (2D) droplet to show that, depending on the initial drop volume and substrate inclination, the solute deposited can be higher at either the top or lower contact line.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Investigation of Evaporation of Ethanol–Water Droplets Laden with Alumina Nanoparticles on a Critically Inclined Heated Substrate

et al. 2022

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We experimentally investigate the evaporation of water−ethanol binary sessile droplets loaded with alumina nanoparticles on a critically inclined heated surface and compare it to the no-loading condition. In contrast to a droplet of pure fluids, several distinct and interesting phenomena observed in a binary-nanofluid droplet on a critically inclined substrate are reported for the first time. The critical angle at which a droplet begins to slide increases for ethanol-rich binary droplets up to 0.6 wt % nanoparticle loading. The critical angle for binary droplets also increases as the substrate temperature increases and as the ethanol concentration decreases for modest loading conditions. It is observed that the advancing side of a binary droplet is pinned in both the loading and no-loading scenarios, whereas the receding side is pinned in the loading case but shrinks continuously in the no-loading case. The pinning effect caused by nanoparticles results in a larger perimeter and surface area for the nanoparticle-laden droplets, enhancing the evaporation rates and significantly decreasing the lifetime of the nanoparticle-containing droplets compared to the no-loading case. Increasing the ethanol percentage in the binary droplet placed on an inclined substrate produces complex thermosolutal Marangoni convection, which becomes more affluent in the case of nanoparticles loading than the no-loading condition. The radial symmetry of the circular coffee ring structure observed on a horizontal surface is shattered in the inclined case because the droplet elongates and preferentially deposits toward the advancing side of the triple line due to the action of the body force. Despite its fundamental nature, the present study can contribute to understanding many practical applications.

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Section: Introductionmentioning

confidence: 99%

An Experimental Investigation of Evaporation of Ethanol–Water Droplets Laden with Alumina Nanoparticles on a Critically Inclined Heated Substrate

et al. 2022

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“…Following the pioneering work of Deegan and co-workers, ,, numerous researchers (e.g., refs − ) have experimentally and theoretically studied the evaporation of sessile droplets of single-component fluids in the presence of nanoparticles at ambient and elevated temperatures. Moffat et al , experimentally analyzed the stick–slip behavior caused by the aggregation of nanoparticles near the triple contact line of a sessile droplet containing nanoparticles at ambient temperature.…”

Section: Introductionmentioning

confidence: 99%

Evaporation Dynamics of a Sessile Droplet of Binary Mixture Laden with Nanoparticles

et al. 2021

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We investigate the evaporation dynamics of a sessile droplet of ethanol–water binary mixtures of different compositions laden with alumina nanoparticles and compare with the no-loading condition at different substrate temperatures. Shadowgraphy and infrared imaging methods are used, and the experimental images are postprocessed using a machine learning technique. We found that the loading and no-loading cases display distinct wetting and contact angle dynamics. Although the wetting diameter of a droplet decreases monotonically in the absence of loading, the droplet with 0.6 wt % nanoparticle loading remains pinned for the majority of its lifetime. The temporal variation of the normalized droplet volume in the no-loading case has two distinct slopes, with ethanol and water phases dominating the early and late stages of evaporation, respectively. The normalized droplet volume with 0.6 wt % loading displays a nearly linear behavior because of the increase in the heat transfer rate. Our results from infrared imaging reveal that a nanofluid droplet displays far richer thermal patterns than a droplet without nanoparticle loading. In nanoparticle-laden droplets, the pinning effect, as well as the resulting thermo-capillary and thermo-solutal convection, causes more intense internal mixing and a faster evaporation rate. Finally, a theoretical model is also developed that satisfactorily predicts the evaporation dynamics of binary nanofluid droplets.

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