Experimental investigation of evaporation from asymmetric microdroplets confined on heated micropillar structures

Li, Shan; Li, Junhui; Ma, Binjian; Jiang, Xinyu; Dogruoz, Baris; Agonafer, Damena

doi:10.1016/j.expthermflusci.2019.109889

Cited by 18 publications

(6 citation statements)

References 50 publications

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“…In order to quantify the influence of buoyancy flow in the vapor domain on evaporation rates, we conducted additional numerical simulations using COMSOL based on a quasi-steady state assumption. The evaporation is predicted by incorporating the thermal diffusion model with convection in the vapor domain. , The simulation methodology and a detailed discussion of the results are provided in Section 5 of the Supporting Information. The numerical results show a strong upward buoyancy flow (∼0.1 m/s) around the droplet.…”

Section: Resultsmentioning

confidence: 99%

“…The evaporation is predicted incorporating the thermal diffusion model with convection in the vapor domain. 59,60 The simulation methodology and a detailed discussion of the results are provided in Section 5 of the Supporting Information. The numerical results show a strong upward buoyancy flow (∼0.1 m/s) around the droplet.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Evaporation of Sessile Water Droplets on Horizontal and Vertical Biphobic Patterned Surfaces

Li²,

Weisensee³

2019

Langmuir

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ABSTACT: This paper presents an experimental study on thermal transport to single water droplets evaporating on heated bi-phobic surfaces consisting of a superhydrophobic matrix with a circular hydrophobic pattern with strong contact line pinning. A single water droplet of 8 µl volume is placed on a preheated surface and allowed to evaporate in an open laboratory environment. We investigate the influence of substrate orientation (horizontal and vertical) on evaporation dynamics. Using optical and infrared imaging, we report droplet fluid dynamics and heat transfer characteristics of the evaporating droplet. Overall, evaporation is more efficient on the vertical surface, exhibiting higher total heat transfer rates and up to 10% shorter evaporation times. Counterintuitively, on the vertical surface, the substrate-droplet interfacial heat flux was higher near the lower contact line than in the upper region, despite a high contact angle and an expected wedge effect at the bottom. At the same time, the temperature is colder in the lower part of the droplet. We attribute this apparent anomaly to the competition between sensible heating and evaporation, and a modified convective flow signature (both within the droplet and the gas phase) compared to a horizontal surface. We also show that the thermal signature becomes uniform once the contact angles at the upper and lower contact lines become equal towards the end of the evaporation process. Insights from this work can guide the design of spray cooling devices, or be used to alter particle deposition patterns during evaporation-based fabrication techniques and ink-jet printing.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Evaporation of Sessile Water Droplets on Horizontal and Vertical Biphobic Patterned Surfaces

Li²,

Weisensee³

2019

Langmuir

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“…The developed methodology can enable the probing of mass-transfer dynamics present in the counter-diffusion problem present during condensation with NCGs present. Indeed, recent studies have developed methodologies to enable the formation of nonaxisymmetric droplets for enhanced evaporation, ,, bringing forth the need for experimental quantification of evaporation physics in more complex systems than studied here.…”

Section: Discussionmentioning

confidence: 99%

Gas-Phase Temperature Mapping of Evaporating Microdroplets

Mousa

Günay

Orejon

et al. 2021

ACS Appl. Mater. Interfaces

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Evaporation is a ubiquitous and complex phenomenon of importance to many natural and industrial systems. Evaporation occurs when molecules near the free interface overcome intermolecular attractions with the bulk liquid. As molecules escape the liquid phase, heat is removed, causing evaporative cooling. The influence of evaporative cooling on inducing a temperature difference with the surrounding atmosphere as well as within the liquid is poorly understood. Here, we develop a technique to overcome past difficulties encountered during the study of heterogeneous droplet evaporation by coupling a piezo-driven droplet generation mechanism to a controlled micro-thermocouple to probe microdroplet evaporation. The technique allowed us to probe the gas-phase temperature distribution using a micro-thermocouple (50 μm) in the vicinity of the liquid−vapor interface with high spatial (±10 μm) and temporal (±100 ms) resolution. We experimentally map the temperature gradient formed surrounding sessile water droplets having varying curvature dictated by the apparent advancing contact angle (100°≲ θ ≲ 165°). The experiments were carried out at temperatures below and above ambient for a range of fixed droplet radii (130 μm ≲ R ≲ 330 μm). Our results provide a primary validation of the centuriesold theoretical framework underpinning heterogeneous droplet evaporation mediated by the working fluid, substrate, and gas thermophysical properties, droplet apparent contact angle, and droplet size. We show that microscale droplets residing on lowthermal-conductivity substrates such as glass absorb up to 8× more heat from the surrounding gas compared to droplets residing on high-thermal-conductivity substrates such as copper. Our work not only develops an experimental understanding of the heat transfer mechanisms governing droplet evaporation but also presents a powerful platform for the study and characterization of liquid−vapor transport at curved interfaces wetting and nonwetting advanced functional surfaces.

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“…1a), which was not possible without any special treatment on the surface. Although there have been a number of studies concerning the physics involved in the edge effect 19,24 and the evaporation characteristics of pinned asymmetric drops, 25–27 the contact line deposition has not yet been fully investigated for them. 23,28…”

Section: Introductionmentioning

confidence: 99%

Geometrically-controlled evaporation-driven deposition of conductive carbon nanotube patterns on inclined surfaces

et al. 2023

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Experimental investigation of evaporation from asymmetric microdroplets confined on heated micropillar structures

Cited by 18 publications

References 50 publications

Evaporation of Sessile Water Droplets on Horizontal and Vertical Biphobic Patterned Surfaces

Evaporation of Sessile Water Droplets on Horizontal and Vertical Biphobic Patterned Surfaces

Gas-Phase Temperature Mapping of Evaporating Microdroplets

Geometrically-controlled evaporation-driven deposition of conductive carbon nanotube patterns on inclined surfaces

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