Investigation spatial distribution of droplets and the percentage of surface coverage during dropwise condensation

Barati, Solmaz Boroomandi; Pionnier, Nicolas; Pinoli, Jean‐Charles; Valette, S.; Gavet, Yann

doi:10.1016/j.ijthermalsci.2017.10.020

Cited by 17 publications

(9 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Mei et al used a computer simulation to obtain the drop distribution also for a contact angle of 90°, but their results were intended for larger drop sizes where the distribution function was already well established . Barati et al used a numerical simulation of dropwise condensation to investigate condensation as a function of time for drops with a contact angle of 88°, though they did not report steady state drop distribution data . Meng et al demonstrated how a computer simulation could incorporate the possibility of coalescence-induced jumping but did not use their model to obtain an expression for the drop-size distribution and focused on predicting heat transfer for drops with a single contact angle (140°) and maximum drop size (30 μm) .…”

Section: Introductionmentioning

confidence: 99%

“…The present work reports a computational approach to obtain the steady state drop-size distribution and associated time-averaged heat transfer rates for dropwise condensation over a range of contact angles from 90 to 180°. Condensation is simulated in a Lagrangian approach, similar in form to previous computational approaches, allowing for coalescence at naturally occurring drop sizes. ,− Unlike previous computational simulations, the present work considers how the departure of drops both by jumping and gravity-induced sweeping influences the steady state drop-size distribution and associated time-averaged heat transfer rates. The present work spans also a larger range of physical conditions than previous studies.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Simulation of Drop-Size Distribution During Dropwise and Jumping Drop Condensation on a Vertical Surface: Implications for Heat Transfer Modeling

et al. 2019

View full text Add to dashboard Cite

Accurate models for condensation heat transfer are necessary to improve condenser design. Drop-size distribution is an important aspect of heat transfer modeling that is difficult to measure for small drop sizes. The present work uses a numerical simulation of condensation which incorporates the possibility of coalescence and coalescenceinduced jumping over a range of drop sizes. Results of the simulation are compared with previous theoretical models and the impact of the assumptions used in those models is explored. In particular, previous drop-size distribution models may predict heat transfer rates less accurately for high contact angles and for coalescence-induced jumping since coalescence occurs over a range of drop sizes and does not always result in departure. The influence of various input parameters (nucleation site distribution approach, nucleation site density, contact angle, maximum drop size, heat transfer modeling to individual drops, and minimum jumping size) on the drop-size distribution and overall heat transfer rate is explored. Assignment of the nucleation site spatial distribution and heat transfer model affect both the drop-size distribution and predicted overall heat transfer rate. Results from the simulation suggest that, when the contact angle is large (as on superhydrophobic surfaces) and no coalescence-induced jumping occurs, the heat transfer may not be as sensitive to the maximum drop-size as previously supposed. Furthermore, this work suggests that when coalescenceinduced jumping occurs, reducing the maximum drop size may not always increase heat transfer since drops similar in size to those removed by coalescence-induced jumping can contribute significantly to the overall heat transfer rate.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulation of Drop-Size Distribution During Dropwise and Jumping Drop Condensation on a Vertical Surface: Implications for Heat Transfer Modeling

et al. 2019

View full text Add to dashboard Cite

show abstract

“…As it was explained in our former works [25,26], the process of dropwise condensation consists of four main steps: nucleation of initial droplets, growth rate due to adsorption, growth rate due to coalescence followed by nucleation of new small droplets, and sliding of the very big droplets from the surface. There are two kinds of growth procedures for each droplet regardless of its size and shape:…”

Section: Growth Rate Of Ellipsoidal Dropletsmentioning

confidence: 99%

“…where k represents each generation of droplets, ∆t is the time step, and , and C 3 = θ 4KwSinθ [25,27]. Miljkovic et al [4,28,29] have done considerable efforts to calculate the growth rate of jumping and non-jumping cassie-baxter and Wenzel droplets on the super-hydrophobic pillared substrates.…”

Section: Adsorptionmentioning

confidence: 99%

Modeling and simulating the growth of ellipsoidal droplets during dropwise condensation on pillared surfaces

Barati

Rabiet

Pinoli

et al. 2019

Applied Thermal Engineering

Self Cite

View full text Add to dashboard Cite

A numerical simulation model is proposed to describe ellipsoidal droplets growth on pillared substrates during dropwise condensation. Comparison between gray scale images taken from droplets growing on pillared surfaces with those growing on flat surfaces shows considerable differences that must be taken into account in the simulation model. Firstly, since the droplets can be easily canalized between the pillars, the shape of droplets change from spherical to ellipsoidal specially in coalescence step. Secondly, on pillared surfaces due to droplets three dimensional configuration, coalescence can occur in all three dimensions. And thirdly, if a droplet touches a pillar, they will stay in touch until the end of the process. The model proposed here calculates the growth rate of ellipsoidal droplets during adsorption and coalescence steps, and checks the coalescence by verifying the existence of real intersection between each pair of droplets. The results of this model is compared with real data from 6 different configurations of pillars. The mean relative error of the model for droplets density is 10.00 ± 0.68%, while it proposes more accurate results for predicting droplets radius with the mean error of 2.28 ± 0.42%.

show abstract

“…For faster atmospheric water capture (and higher heat transfer), water should condense in droplet form (dropwise condensation, contact angle > 0°), rather than filmwise condensation, [ 22–27 ] as droplets drastically decrease the thermal resistance of the process. Droplets should roll‐off the surface at small volumes, allowing the free surface area to nucleate new droplets at a higher rate.…”

Section: Introductionmentioning

confidence: 99%

Quantification of Nucleation Site Density as a Function of Surface Wettability on Smooth Surfaces

Katselas

Parin

Neto

2022

Adv Materials Inter

View full text Add to dashboard Cite

In most climatic conditions, radiative cooling of typical surfaces results in only a few degrees of subcooling, and dew only forms a few hours per night on some nights. [3,4] Even so, dew is considered an important source of water for basic sustenance of plants and animals, especially in arid and semiarid regions. [11,12] In the past 20 years, research has been dedicated to obtaining design principles that lead to the most efficient dew water collection on artificial surfaces. [3,[13][14][15] The efficiency of atmospheric water collection (as well as the efficiency of processes of industrial relevance, such as heat transfer in cooling towers) depends on the ability of a surface to first nucleate water droplets at a high rate, and shed those droplets at low volumes, so they can be collected. [16][17][18][19] Classical nucleation theory teaches that the free energy barrier for nucleation ΔG is lower for ideal planar surfaces that are highly wettable by water (low water contact angle), and can be estimated by the following equation [20]

show abstract

Investigation spatial distribution of droplets and the percentage of surface coverage during dropwise condensation

Cited by 17 publications

References 33 publications

Simulation of Drop-Size Distribution During Dropwise and Jumping Drop Condensation on a Vertical Surface: Implications for Heat Transfer Modeling

Simulation of Drop-Size Distribution During Dropwise and Jumping Drop Condensation on a Vertical Surface: Implications for Heat Transfer Modeling

Modeling and simulating the growth of ellipsoidal droplets during dropwise condensation on pillared surfaces

Quantification of Nucleation Site Density as a Function of Surface Wettability on Smooth Surfaces

Contact Info

Product

Resources

About