Evolution of a Water Pendant Droplet: Effect of Temperature and Relative Humidity

Portuguez, Etienne; Alzina, Arnaud; Michaud, Philippe; Oudjedi, M.; Smith, Agnès

doi:10.4236/ns.2017.91001

Cited by 13 publications

(11 citation statements)

References 30 publications

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“…The first of these, the surface tension γ LV , is known from pendant drop measurements to have a smooth change with temperature and RH over the range used in our experiments (72.2−75.5 mN m −1 ). 37,38 However, the second of these, the solid−vapor interfacial tension γ SV , is a candidate for the origin of a step change in the observed contact angle. This might occur if a film of vapor condensed on the solid over the narrow 30−40% range of RH, thereby replacing the solid− vapor interface by solid−liquid and liquid−vapor interfaces.…”

Section: Analysis and Discussionmentioning

confidence: 99%

Pinning-Free Evaporation of Sessile Droplets of Water from Solid Surfaces

et al. 2019

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Contact-line pinning is a fundamental limitation to the motion of contact lines of liquids on solid surfaces. When a sessile droplet evaporates, contact-line pinning typically results in either a stick–slip evaporation mode, where the contact line pins and depins from the surface in an uncontrolled manner, or a constant contact-area mode with a pinned contact line. Pinning prevents the observation of the quasi-equilibrium constant contact-angle mode of evaporation, which has never been observed for sessile droplets of water directly resting on a smooth, nontextured, solid surface. Here, we report the evaporation of a sessile droplet from a flat glass substrate treated with a smooth, slippery, omni-phobic covalently attached liquid-like coating. Our characterization of the surfaces shows high contact line mobility with an extremely low contact-angle hysteresis of ∼1° and reveals a step change in the value of the contact angle from 101° to 105° between a relative humidity (RH) of 30 and 40%, in a manner reminiscent of the transition observed in a type V adsorption isotherm. We observe the evaporation of small sessile droplets in a chamber held at a constant temperature, T = (25.0 ± 0.1) °C and at constant RH across the range RH = 10–70%. In all cases, a constant contact-angle mode of evaporation is observed for most of the evaporation time. Furthermore, we analyze the evaporation sequences using the Picknett and Bexon ideal constant contact-angle mode for diffusion-limited evaporation. The resulting estimate for the diffusion coefficient, D E, of water vapor in air of D E = (2.44 ± 0.48) × 10–5 m2 s–1 is accurate to within 2% of the value reported in the literature, thus validating the constant contact-angle mode of the diffusion-limited evaporation model.

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Section: Analysis and Discussionmentioning

confidence: 99%

Pinning-Free Evaporation of Sessile Droplets of Water from Solid Surfaces

et al. 2019

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“…Recent studies described the evolution of surface tension not only as a function of temperature but also as a function of relative humidity [8] [9]. This article provides new local data about the behavior of liquid bridges in a confined geometry.…”

Section: Introductionmentioning

confidence: 93%

Evaporation Kinetics and Breaking of a Thin Water Liquid Bridge between Two Plates of Silicon Wafer

Portuguez¹,

Alzina²,

Michaud³

et al. 2016

AMPC

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In ceramic processing, the study of the different phases of the drying stage considers the material at a macroscopic scale. Very often, the various parameters (among which the temperature and the relative humidity) are chosen in an empirical way, mostly through visual observations. This stage is governed by capillary phenomena which take place within the material, responsible for both the shrinkage and the risk of cracks which can damage the final piece. As part of a better understanding of the local mechanisms during drying, liquids contained in the pores have been reproduced in an ideal case. Drying kinetics and parameter measurements from 303 to 343 K of deionized water liquid bridges between two plates of silicon wafers are presented. Experimental work was carried out using specific device to create liquid bridges, coupled with image analysis and within an adapted instrumented climatic chamber. While the volume and the exchange surface of liquid bridges decrease regularly throughout the drying process, contact angles only diminish at the end. One of the four contact angles may have a different variation, which results in a pinned contact line in its area and reveals a local change of the surface state. From these measurements and observations, the liquid bridge break is proposed as a cracking criterion of porous materials during drying. Indeed, the challenge is to limit the risk of cracking and damaging pieces during this crucial step in material processing.

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“…also acting as a surfactant [9] [10]. This article provides new local data about the behavior of liquid bridges in hydrophobic contacts in a confined geometry.…”

Section: Introductionmentioning

confidence: 99%

Study of the Contact and the Evaporation Kinetics of a Thin Water Liquid Bridge between Two Hydrophobic Plates

Portuguez¹,

Alzina²,

Michaud³

et al. 2017

AMPC

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The evaporation of sessile water droplets on hydrophobic surfaces is a topic which led to numerous investigations. However, how does the liquid behave when the evaporation occurs between two of these particular substrates? The drying stage is governed by capillary phenomena which takes place in a confined space. In the field of material shaping, it is also possible that some regions of a green body exhibit hydrophobic properties. As part of a better understanding of the local mechanisms during drying, liquid bridges have been reproduced in an ideal case. Drying kinetics and parameters measurements from 303 to 343 K (relative humidity of 55%) of deionized water liquid bridges between two plates of hydrophobic substrates are presented. Experimental work was carried out using a specific device to create liquid bridges, coupled with image analysis within an adapted instrumented climatic chamber. While the volume and the exchange surface of liquid bridges decrease regularly throughout the process, contact angles constantly diminish and more significantly at the end. This is different from the evaporation between two hydrophilic plates. From these measurements, the change of curvature of the liquid bridges during evaporation is highlighted.

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Evolution of a Water Pendant Droplet: Effect of Temperature and Relative Humidity

Cited by 13 publications

References 30 publications

Pinning-Free Evaporation of Sessile Droplets of Water from Solid Surfaces

Pinning-Free Evaporation of Sessile Droplets of Water from Solid Surfaces

Evaporation Kinetics and Breaking of a Thin Water Liquid Bridge between Two Plates of Silicon Wafer

Study of the Contact and the Evaporation Kinetics of a Thin Water Liquid Bridge between Two Hydrophobic Plates

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