3D numerical simulation of condensation and condensate behaviors on textured structures using lattice Boltzmann method

Li, Mingjie; Qu, Jingguo; Ocłoń, Paweł; Wei, Jinjia; Tao, Wen‐Quan

doi:10.1016/j.ijheatmasstransfer.2020.120198

Cited by 18 publications

(8 citation statements)

References 25 publications

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“…Accordingly, the distance between hydrophilic islands affected both droplet growth rate and coalescence-induced droplet departure and was an important parameter for enhancing condensation heat transfer. In addition, the Lattice Boltzmann method has been applied in multiphase flows and phase change heat transfer. , Moreover, in recent studies regarding the Lattice Boltzmann phase change model, surfaces with heterogeneous mixed wettability, different wettability, and textured structures were considered for condensation heat transfer.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the Lattice Boltzmann method has been applied in multiphase flows and phase change heat transfer. 28,29 Moreover, in recent studies regarding the Lattice Boltzmann phase change model, surfaces with heterogeneous mixed wettability, 30 different wettability, 31 and textured structures 32 were considered for condensation heat transfer.…”

Section: Introductionmentioning

confidence: 99%

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Copper-Based Superhydrophobic Nanostructures for Heat Transfer in Flow Condensation

Chehrghani

Abbasiasl

Sadaghiani

et al. 2021

ACS Appl. Nano Mater.

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Superhydrophobic surfaces enhance the condensation heat transfer performance by facilitating removal of condensed droplets and coalescence-induced droplet jumping. During the last decade, studies on superhydrophobic surfaces have been mostly limited to working conditions, which are ideal for electron microscopy techniques. Therefore, the behavior of condensed droplets in the presence of a vapor flow with different vapor qualities and their implementation in flow condensation heat transfer enhancement have received rather little attention, which is the motivation behind this study. Thus, beside heat transfer analysis, we performed a visualization study on flow condensation in a minichannel and investigated droplet dynamics, including a histogram of droplet diameter distribution at different time intervals and stages of a condensation cycle consisting of nucleation growth and departure, droplet departure diameters, cycle time, and droplet number density. The droplet departure diameter decreases with steam mass flux, leading to a shift to smaller radii in droplet size distribution, which enhances condensation heat transfer. Enhancements up to 33% in the heat transfer coefficient were obtained at lower steam qualities for the tested superhydrophobic surface compared to the reference plain hydrophobic surface. We demonstrated that in addition to the high vapor shear stress exerted by the flow on the interface of the vapor and the condensed droplet, the advantage of an inherently unique water repellency feature of the nanostructured superhydrophobic surface can be utilized in flow condensation for enhancing condensation heat transfer.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Copper-Based Superhydrophobic Nanostructures for Heat Transfer in Flow Condensation

Chehrghani

Abbasiasl

Sadaghiani

et al. 2021

ACS Appl. Nano Mater.

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show abstract

“…In a prior study, we demonstrated that although the force analysis on droplets in confined channels could be a complex process, a simplified analysis could be done to clarify that the droplet departure diameter decreases with the steam velocity. 55 As seen in Figure 4a, when the mass flux increases from 10 to 30 kg/m 2 s, the droplet departure diameters considerably decrease in size. This decrease is even more significant when the mass flux is increased from 30 to 50 kg/m 2 s. Previously, we showed that on a superhydrophobic surface, the size of the droplets even gets smaller, and hence, the droplet departure frequency increases when compared to a plain hydrophobic surface.…”

Section: Resultsmentioning

confidence: 86%

“…This occurs when either the size of the droplet or the SMF reaches a minimum value. In a prior study, we demonstrated that although the force analysis on droplets in confined channels could be a complex process, a simplified analysis could be done to clarify that the droplet departure diameter decreases with the steam velocity . As seen in Figure a, when the mass flux increases from 10 to 30 kg/m 2 s, the droplet departure diameters considerably decrease in size.…”

Section: Resultsmentioning

confidence: 93%

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Biphilic Surfaces with Optimum Hydrophobic Islands on a Superhydrophobic Background for Dropwise Flow Condensation

et al. 2021

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Sustaining dropwise condensation is of great importance in many applications, especially in confined spaces. In this regard, superhydrophobic surfaces enhance condensation heat transfer performance due to the discrete droplet formation and rapid removal. On the other hand, droplets tend to nucleate easier and faster on hydrophobic surfaces compared to superhydrophobic ones. To take advantage of the mixed wettability, we fabricated biphilic surfaces and integrated them to small channels to assess their effect on thermal performance in flow condensation in small channels. Hydrophobic islands in the range of 100–900 μm diameter were fabricated using a combination of wet etching, surface functionalization, and physical vapor deposition (PVD) techniques. Condensation experiments were performed in a minichannel with a length, width, and height of 37, 10, and 1 mm, respectively. Here, we report optimum island diameters for the hydrophobic islands in terms of the maximum thermal performance. We show that considering the optimum point for each steam mass flux corresponding to the best heat transfer performance, the condensation heat transfer coefficient is increased by 51, 48, 42, 40, and 36% compared to the plain reference hydrophobic surface for steam mass fluxes of 10, 20, 30, 40, and 50 kg/m2 s, respectively. The optimum island diameters are obtained as 200, 300, 400, 400, and 500 μm, with the ratios of hydrophobic to superhydrophobic surface areas (A* = A hydrophobic/A superhydrophobic) of 3.2, 7.6, 14.4, 14.4, and 24.4%, for steam mass fluxes of 10, 20, 30, 40, and 50 kg/m2 s, respectively. The liquid film forming on the liquid–vapor interface acts as an insulation layer and generates thermal resistance, and bridges appear on the patterned areas and deteriorate the thermal performance. Therefore, it is crucial to characterize the role of droplet mobility on biphilic surfaces to avoid the occurrence of bridging. Through visualization, we demonstrate that the optimum conditions correspond to enhanced droplet nucleation and rapid sweeping regions, where droplet pinning and bridging do not occur. The trends in condensation heat transfer with surface mixed wettability can be divided into three regions: enhanced droplet nucleation and rapid sweeping, highly pinned droplet, and bridging droplet segments. We reveal that the interfacial heat transfer augmentation in the enhanced droplet nucleation and rapid sweeping region is due to both spatial control of droplet nucleation and an increase in the sweeping period. Furthermore, by fitting the experimental data, a correlation for predicting the optimum island diameter for biphilic surfaces is proposed for condensation heat transfer in confined channels, which will be a valuable guideline for engineers and researchers working on the design and development of thermal systems.

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Manufacturing of durable tribological surface by grinding process

Musavi

Adibi

Rezaei

2022

Int J Adv Manuf Technol

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3D numerical simulation of condensation and condensate behaviors on textured structures using lattice Boltzmann method

Cited by 18 publications

References 25 publications

Copper-Based Superhydrophobic Nanostructures for Heat Transfer in Flow Condensation

Copper-Based Superhydrophobic Nanostructures for Heat Transfer in Flow Condensation

Biphilic Surfaces with Optimum Hydrophobic Islands on a Superhydrophobic Background for Dropwise Flow Condensation

Manufacturing of durable tribological surface by grinding process

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