On wetting characteristics of droplet on a spherical particle in film boiling regime

Mitra, Subhasish; Nguyen, Thi Bang Tuyen; Doroodchi, Elham; Pareek, Vishnu; Joshi, Jyeshtharaj B.; Evans, Geoffrey M.

doi:10.1016/j.ces.2016.04.003

Cited by 68 publications

(31 citation statements)

References 43 publications

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“…Mitra et al studied the deformation of water, isopropanol and acetone droplet collision on copper particles at 250°C using a high‐speed camera and captured the vapor region around the evaporating droplets by Schlieren imaging. This group observed rebound and complete disintegration under 250–350°C, which were divided by a critical Weber number range rather than a single threshold. They also studied the droplet–particle with the size ratio close to 1 under normal and elaborated on the nucleate boiling, and gave a time‐dependent scheme for different stages.…”

Section: Introductionmentioning

confidence: 96%

Experimental characterization of liquid film behavior during droplets–polyethylene particle collision

et al. 2020

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Nowadays, the droplet–particle collision characteristics in the gas‐phase ethylene polymerization process are still unclear. The high‐speed photography and a quasi‐circle imaging approach are employed to study the collision interaction characteristics between liquid droplets and polyethylene particles. The liquid film evolution is studied through variations of the film thickness on the particle north pole, the dynamic contact angle, center angle and film thickness at the maximum extension. Results have found that for n‐hexane the threshold temperature of the recoil happening increases with increasing initial Weber number, but for 1‐hexene it is stable. Over 70°C evaporation and splash occurs immediately. Under low Weber numbers, the water droplet stays for damping oscillations, the reference stable height of which is linearly related to temperatures. Moreover, three regimes of film thickness variation with time are identified and mathematically described, while Regime 3 characteristics are found strongly dependent on the liquid species, Weber number, and particle temperature.

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Section: Introductionmentioning

confidence: 96%

Experimental characterization of liquid film behavior during droplets–polyethylene particle collision

et al. 2020

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“…Dynamic wetting of particle surface is an important research aspect in the area of multiphase flows. Ample process applications such as spray coating of tablets in pharmaceutical applications (Hardalupas et al, 1999 ), vaporization of vacuum gas oil feed droplets in contact with catalyst particles in fluid catalytic cracking unit (Ge and Fan, 2007 ; Mitra et al, 2013 , 2015 , 2016 , 2017 ; Nguyen et al, 2015 ; Banitabaei and Amirfazli, 2017 ), spray drying (Charalampous and Hardalupas, 2017 ), thermal cracking of bitumen feed in fluid coking unit, scrubbing of particulate matters from off-gas stream (Mitra et al, 2013 , 2015 , 2016 , 2017 ) require adequate surface wetting of particles. Dynamic wetting of particle surface resulting from such interactions contribute significantly to the liquid distribution on particle surface, associated heat-mass transport processes, and chemical reactions each of which governs the process performance.…”

Section: Introductionmentioning

confidence: 99%

“…Central to the surface wetting behavior is the three-phase contact line motion which changes drastically as a consequence of the several outcomes that are possible based on interacting droplet-particle size ratio (Δ) such as deposition, rebound, disintegration (Δ < 1) (Ge and Fan, 2007 ; Mitra et al, 2013 , 2016 ); capture, penetration, disintegration (Δ> 1) (Mitra et al, 2015 ), deposition, film formation and disintegration (Δ ~ 1) (Bakshi et al, 2007 ; Gac and Gradon, 2014 ; Banitabaei and Amirfazli, 2017 ; Mitra et al, 2017 ). For Δ < 1 scenario, upon impact on the solid surface, droplet spreads into a liquid lamella wherein the impact kinetic energy is transformed into the surface energy and the spreading process continues until the kinetic energy is completely dissipated and a maximum spreading state is reached.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Surface Wetting and Heat Transfer in a Droplet-Particle System of Less Than Unity Size Ratio

Mitra

Evans

2018

Front. Chem.

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Dynamic surface wetting of particles in contact with droplet is a complex phenomenon ubiquitously encountered in many multiphase systems of industrial importance. In this study, we address this aspect by investigating impact behavior of a water droplet (diameter = 2.9 ± 0.1 mm) in the Weber number (We) range from ~4 to 104 on a stationary spherical brass particle (diameter = 10 mm) with and without heat transfer using a combination of high speed imaging and computational fluid dynamics (CFD) modeling approach. In cold state interactions (20°C), droplet exhibited oscillatory interfacial motion comprising periodic spreading and recoiling motion. Interactions involving heat transfer were studied in film boiling regime (350°C) and two outcomes were noted—droplet rebound and disintegration. A coupled Level Set and Volume of Fluid (VOF) approach based multiphase CFD model was utilized to predict the dynamic spread ratio and transient evolution of droplet shape during the interaction. To capture the complex contact line motion realistically, a continuous time varying profile of experimentally measured dynamic contact angles was used as a wall boundary condition for the cold interactions which provided good agreement with experimentally measured droplet spread ratio. In film boiling regime, droplet spread ratio was correlated to impact Weber number and a power law trend was obtained. Rebound and disintegration outcomes were characterized by the droplet-particle contact time. For simulating interactions in film boiling regime, a constant contact angle in the limit of super-hydrophobic surface was implemented in the CFD model to account for the apparent non-wetting effect due to vapor film formation at the contact area. A sensitivity analysis was performed involving three different contact angle boundary conditions (θs = 150, 160, and 170°) to represent the surface hydrophobicity. CFD model predicted interaction outcomes and droplet spread ratios were in reasonable agreement with the experiment at different impact Weber numbers. Increase in spherical surface heat flux and corresponding rise in droplet temperature at different impact Weber numbers were also quantified which showed an increasing trend up to a critical Weber number for droplet disintegration.

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“…Droplet temperature was found to have no effect on the crack formation while the formation of a thin layer of frost on the sphere before the drop impact led to the lateral cracking of the ice. Mitra et al [11] studied droplet-particle interaction of size ration less than unity in the film boiling regime on a highly thermally conductive spherical particle surface. They found a critical Weber number range, noted from rebound to disintegration regime transitions.…”

Section: Introductionmentioning

confidence: 99%

“…Even though some researches have been performed on the impact process of a water droplet on spherical surfaces in previous studies [3][4][5][6][7][8][9][10][11], to the authors' best knowledge, only limited study of a water droplet impact and freezing processes on super cold spherical surfaces (−50°C) has been experimentally performed [10]. According to the Ref.…”

Section: Introductionmentioning

confidence: 99%

The impact and freezing processes of a water droplet on different cold spherical surfaces

Jin

Zhang

et al. 2018

Experimental Thermal and Fluid Science

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On wetting characteristics of droplet on a spherical particle in film boiling regime

Cited by 68 publications

References 43 publications

Experimental characterization of liquid film behavior during droplets–polyethylene particle collision

Experimental characterization of liquid film behavior during droplets–polyethylene particle collision

Dynamic Surface Wetting and Heat Transfer in a Droplet-Particle System of Less Than Unity Size Ratio

The impact and freezing processes of a water droplet on different cold spherical surfaces

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