Growth of droplets on a substrate by diffusion and coalescence

Steyer, Alexandre; Guénoun, P.; Beysens, Daniel; Knobler, Charles M.

doi:10.1103/physreva.44.8271

Cited by 60 publications

(52 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Detailed experimental and analytical studies on the dynamics of the BF on solid surfaces have already been performed [9,[11][12][13]18,19]. However, the studies of the dynamics of the inhibited condensation regime in the neighborhood of a single growing drop have been quite limited and have only been performed with an NaCl saturated drop, where the water vapor pressure is p s0 0.76p s .…”

Section: F Region Of Inhibited Condensationmentioning

confidence: 99%

Droplet pattern and condensation gradient around a humidity sink

et al. 2014

View full text Add to dashboard Cite

We describe the evolution of a water drop saturated with NaCl and the growth of pure water droplets in a breath figure pattern (BF) condensing around it. This salty drop acts as a humidity sink, inhibiting the BF inside a ring at a distance r = δ from the sink center and slowing down BF growth outside the ring. The initial salty drop is taken either from a salt-saturated solution (type I experiment) or by placing an NaCl crystal on the substrate (type II experiment). The results are similar, provided that the initial time for type II evolution is taken at the end of the crystal dissolution. The evolution of the salty drop radius R is deduced from the establishment of a three-dimensional hyperbolic concentration profile around the salty drop. This profile scales with r/δ. Accounting for the salt concentration decrease with salty drop growth, R is seen to grow as t 5 . In the region r > δ, water droplets nucleate and grow. The rate of evolution of the water droplets at constant r/δ can be used to determine the local water pressure. The corresponding data reasonably agree with a hyperbolic water vapor profile around the salty drop. These results can be applied to the growth of BF patterns to determine whether hyperbolic or linear water vapor profiles apply.

show abstract

Section: F Region Of Inhibited Condensationmentioning

confidence: 99%

Droplet pattern and condensation gradient around a humidity sink

et al. 2014

View full text Add to dashboard Cite

show abstract

“…In a study by Beysens et al [54,55], numerical simulations were also used with scaling arguments to investigate water vapour condensation on hydrophobic surfaces. The authors focused specifically on the initial steps of the process.…”

Section: Surface Topographymentioning

confidence: 99%

Low Pressure Radio Frequency Ammonia Plasma Surface Modification on Poly(ethylene terephthalate) Films and Fibers: Effect of the Polymer Forming Process

Öteyaka

Chevallier

Turgeon

et al. 2011

Plasma Chem Plasma Process

View full text Add to dashboard Cite

We investigated the effect of a polyethylene terephthalate (PET) forming process on radiofrequency ammonia plasma surface-treated PET flat films and fibres obtained by melt blowing. Ammonia plasma treatment allowed for the incorporation of amino functionalities on both the film and fibre surfaces, with higher values observed at very short treatment times. This plasma treatment also induced polymer chain scissions which were observed as the formation of hydrophilic nodules that coalesced together and were loosely bound to the underlying polymeric materials. These plasma-induced surface damages were notably more important on the melt-blown PET fibres. Consequently, maximisation of the surface amino groups with minimal polymer chain breaking was achieved using very short plasma treatment times (typically 1 s). We also demonstrated that the polymer forming process must be taken into account when plasma modifications are to be performed on PET, as it may already lead to polymer chain breakings subsequently added to those induced in the plasma environment.

show abstract

“…Other studies have previously indicated that single droplet growth-law exponents are sensitive to boundary conditions that influence the pattern of vapor mass flow to the surface from the surroundings [14]. To assess the influence of relative humidity on the growth only by direct condensation on the droplet interfaces (excluding growth by coalescence), the condensation mass flux on the interfaces of the individual droplets is calculated based on the instantaneous rate of change of droplet radius (omitting step changes due to coalescence).…”

Section: Single Droplet Growthmentioning

confidence: 99%

The effect of relative humidity on dropwise condensation dynamics

Castillo

Weibel

Garimella

2015

International Journal of Heat and Mass Transfer

View full text Add to dashboard Cite

Dropwise condensation of atmospheric water vapor is important in multiple practical engineering applications. The roles of environmental factors and surface morphology/chemistry on the condensation dynamics need to be better understood to enable efficient water-harvesting, dehumidication, and other psychrometric processes. Systems and surfaces that may promote faster condensation rates and selfshedding of condensate droplets could lead to improved mass transfer rates and higher water yields in harvesting applications. In the present study, experiments are performed in a facility that allows visualization of the condensation process on a vertically oriented, hydrophobic surface at a controlled relative humidity and surface subcooling temperature. The distribution and growth of water droplets are monitored across the surface at different relative humidities (45%, 50%, 55%, and 70%) at a constant surface subcooling temperature of 15 °C below the ambient temperature. The droplet growth dynamics exhibits a strong dependency on relative humidity in the early stages during which there is a large population of small droplets on the surface and single droplet growth dominates over coalescence effects.At later stages, the dynamics of droplet growth is insensitive to relative humidity due to the dominance of coalescence effects. The overall volumetric rate of condensation on the surface is also assessed as a function of time and ambient relative humidity. Low relative humidity conditions not only slow the absolute rate of condensation, but also prolong an initial transient regime over which the condensation rate remains significantly below the steady-state value.Keywords: dropwise condensation, relative humidity, growth dynamics, droplet distribution,

show abstract

Growth of droplets on a substrate by diffusion and coalescence

Cited by 60 publications

References 7 publications

Droplet pattern and condensation gradient around a humidity sink

Droplet pattern and condensation gradient around a humidity sink

Low Pressure Radio Frequency Ammonia Plasma Surface Modification on Poly(ethylene terephthalate) Films and Fibers: Effect of the Polymer Forming Process

The effect of relative humidity on dropwise condensation dynamics

Contact Info

Product

Resources

About