Droplet Nucleation and Growth in the Presence of Noncondensable Gas: A Molecular Dynamics Study

Dong, Ning; Gao, Hongtao; Yan, Yuying

doi:10.1021/acs.langmuir.1c00961

Cited by 21 publications

(16 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As shown in Figure 6a, the number of liquid molecules first oscillates around N liq = 10 and then increases rapidly at τ = 1000 ps on the partially wetting surface while showing an instant increase once the vapor temperature drops to 400 K (τ = 0 ps) on the completely wetting surface. This distinctive condensation process on the partially wetting surface has also been observed in previous studies, 45 indicating the significant differences between the heterogeneous condensation on partially and completely wetting surfaces.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The condensation simulations are performed using the GCMC+MD method, which has been demonstrated to be effective in simulating condensation processes. − The GCMC method is adopted to maintain the vapor pressure of the system through the whole simulation by inserting or deleting fluid molecules in a specific region. The velocity-Verlet algorithm is utilized to update the particle velocities and positions.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Formation of Liquid Film in Heterogeneous Condensation of Water Vapor: Effects of Solid–Fluid Interaction and Sulfuric Acid Component

et al. 2022

View full text Add to dashboard Cite

Understanding the phenomenon of filmwise condensation on solid surfaces is vital for industrial processes such as air pollutant control and desalination. In this work, we study the formation of condensed liquid films via molecular dynamics simulations, and the effects of solid−fluid interactions and the sulfuric acid component are given major attention. Water is chosen as the fluid, while the solid−fluid interaction is modified to characterize different solid surfaces. The results show that as the solid−fluid interaction decreases, the solid surface transforms from a completely wetting surface to a partially wetting surface, and the film formation process shows significant differences. The condensed liquid on the completely wetting surface forms small liquid films, which merge to form a complete film covering the surface. With the enhancement of solid−fluid interaction, the condensation rate increases first and then remains virtually invariant, resulting in a film formation time that decreases first and then maintains constant. The condensed liquid on the partially wetting surfaces appears as nanodroplets, and the coalescence between nanodroplets leads to the formation of the liquid film. It is found that the stronger the solid−fluid interaction, the more the coalesced droplets tend to be pinned at nucleation sites, the easier it is to form a liquid film, and the shorter the time required for droplet merging. The sulfuric acid component accelerates liquid film formation on both completely wetting and partially wetting surfaces, but the effect of sulfuric acid is more significant on partially wetting surfaces. The 5% molar fraction of sulfuric acid reduces the nucleation time by 72% and increases the condensation rate by 137% under partial wetting, while the same amount of sulfuric acid only increases the nucleation rate by 6% on the completely wetting surface.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Formation of Liquid Film in Heterogeneous Condensation of Water Vapor: Effects of Solid–Fluid Interaction and Sulfuric Acid Component

et al. 2022

View full text Add to dashboard Cite

show abstract

“…[ 43 ] Although the nucleation densities shown in Figure 3 are low compared to the typical values reported on metallic substrates, [ 52,53 ] we emphasize here that, in addition to the rigidity of the substrate, the nucleation density during condensation is also sensitive to other factors such as surface roughness, level of subcooling [ 54 ] and fraction of non‐condensable gases in water vapor. [ 55 ] Additionally the thermal conductivity of these soft organogels of around 0.2 W mK −1[ 56,57 ] is much lower compared to metals, such as Copper and Aluminium, that are typically used in heat transfer applications. Thus we have compared the dewing performance of P10L0 and hydrophobic copper substrates under same atmospheric humidity and subcooling conditions.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Condensation on Soft Materials through Bulk Lubricant Infusion

Sharma

Milionis

Naga

et al. 2021

Adv Funct Materials

View full text Add to dashboard Cite

Soft substrates enhance droplet nucleation during water vapor condensation because their deformability inherently reduces the energetic threshold for heterogeneous nucleation relative to rigid substrates. However, this enhancement is counteracted later in the condensation cycle, when substrate viscoelastic dissipation inhibits condensate droplet shedding. Here a polydimethylsiloxane (PDMS) based organogel is designed to overcome this limitation. It is shown that merely 5% bulk lubricant infusion in PDMS reduces viscoelastic dissipation in the substrate by nearly 28 times while doubling the droplet nucleation density. Parameters for water condensation on this organogel are correlated with material properties controlled by design, i.e., fraction and composition of uncrosslinked chains and shear modulus. It is demonstrated that the increase in nucleation density and reduction in precoalescence droplet growth rate is rather insensitive to the lubricant percentage in PDMS within the broad range investigated. These results indicate the presence of a lubricant layer on the substrate surface that cloaks the growing condensate droplets. This cloaking effect is visualized, and it is shown that cloaking occurs significantly faster on PDMS if it is infused with bulk lubricant. Overall, bulk lubricant infusion in PDMS enhances condensation and leads to a more than 40% higher dewing on the substrate.

show abstract

“…On the other hand, researchers have begun to seek inspiration from the natural world to pursue better water vapor condensation performance. The condensation processes on various bionic surfaces with special wettabilities and micro/nanostructures have attracted tremendous attention. − Based on the special surface functions and characteristics on creature surfaces, such as the self-cleaning function on the locus, the antifog characteristics on dragonfly wings, and the directional detachment of condensed droplets on the butterfly surface, diverse bionic surfaces were designed, and the efficient vapor condensation process was put forward, which included the following condensation characteristics: rapid droplet nucleation, high growth rate, and effective removal of condensed droplets. − Typically, inspired by Namble dessert beetles, the simplified beetle bionic surface with hybrid wettabilities was constructed for water vapor condensation experiments, and researchers discovered that the condensation performance on beetle bionic surfaces with different hydrophilic micropillar diameters was better than that on the surface patterned only with hydrophobic nanograss . Moreover, through constructing nanopillars with hybrid wettabilities on the surface, it was observed that the condensation performance was improved compared with that on the surface with homogeneous hydrophobic nanopillars, and the enhancement of heat and mass transfer performance could be attributed to the steady dropwise condensation and regular nucleation .…”

Section: Introductionmentioning

confidence: 99%

Vapor Condensation on Bioinspired Hierarchical Nanostructured Surfaces with Hybrid Wettabilities

et al. 2022

View full text Add to dashboard Cite

Vapor condensation on bioinspired hierarchical nanostructured surfaces with hybrid wettabilities has been investigated using molecular dynamics simulations. A series of hierarchical surfaces consisting of nanocylinder arrays with hydrophilic top and hydrophobic nanopillar arrays are constructed. The results manifest that the condensed nanodroplets undergo three states in the whole water vapor condensation process, and the total condensed atom number on surfaces increases with the increase of nanocylinder diameter (D), which indicates that the introduction of hydrophilic nanocylinders is conducive to improving the condensation performance compared with that on the hydrophobic surface patterned with homogeneous nanopillars. However, the nucleation sites on hierarchical nanostructured surfaces are covered by the condensed nanodroplets at the end of condensation, which suppresses the further enhancement of condensation performance. To solve these problems, we add a collection region close to the edge of the nanostructured surface. It is noticed that the condensed nanodroplets can roll into the collection regions gradually during the condensation process, which keeps the nucleation sites on nanostructured surfaces exposed effectively, especially for the cases of 20 Å ≤ D ≤ 40 Å. Moreover, the cluster number, the total condensed atom number, and the condensation enhancement efficiency on hierarchical nanostructured surfaces with collection regions at 20 Å ≤ D ≤ 40 Å are higher obviously compared with those on surfaces without collection regions. Our study demonstrates that the bioinspired hierarchical nanostructured surface with the collection region is beneficial to boost the vapor condensation performance, which can bring new insights into water vapor condensation.

show abstract

Droplet Nucleation and Growth in the Presence of Noncondensable Gas: A Molecular Dynamics Study

Cited by 21 publications

References 52 publications

Formation of Liquid Film in Heterogeneous Condensation of Water Vapor: Effects of Solid–Fluid Interaction and Sulfuric Acid Component

Formation of Liquid Film in Heterogeneous Condensation of Water Vapor: Effects of Solid–Fluid Interaction and Sulfuric Acid Component

Enhanced Condensation on Soft Materials through Bulk Lubricant Infusion

Vapor Condensation on Bioinspired Hierarchical Nanostructured Surfaces with Hybrid Wettabilities

Contact Info

Product

Resources

About