A computational study of droplet evaporation with fuel vapor jet ejection induced by localized heat sources

Sim, Jaeheon; Im, Hong G.; Chung, Suk Ho

doi:10.1063/1.4919809

Cited by 7 publications

(4 citation statements)

References 34 publications

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“…Finally, it is important to point out that the suppression of surface tension forces adopted in this work could in principle affect the internal motion in the liquid phase, because of the different the tangential shear stress at the interface. However, our comparative analyses in this sense, not reported in this work, show that the results obtained with DropletSMOKE++ are in a reasonable agreement both with experimental [66,67] and numerical [36,68] works not based on the VOF methodology. These investigations are still preliminary, but indicate that even neglecting surface tension the internal circulation phenomenon can be quantitatively and qualitatively captured with a reasonable accuracy.…”

Section: Numerical Results and Discussionsupporting

confidence: 66%

DropletSMOKE++: A comprehensive multiphase CFD framework for the evaporation of multidimensional fuel droplets

Saufi¹,

Frassoldati²,

Faravelli³

et al. 2019

International Journal of Heat and Mass Transfer

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This paper aims at presenting the DropletSMOKE++ solver, a comprehensive multidimensional computational framework for the evaporation of fuel droplets, under the influence of a gravity field and an external fluid flow. The Volume Of Fluid (VOF) methodology is adopted to dynamically track the interface, coupled with the solution of energy and species equations. The evaporation rate is directly evaluated based on the vapor concentration gradient at the phase boundary, with no need of semi-empirical evaporation sub-models.The strong surface tension forces often prevent to model small droplets evaporation, because of the presence of parasitic currents. In this work we by-pass the problem, eliminating surface tension and introducing a centripetal force toward the center of the droplet. This expedient represents a major novelty of this work, which allows to numerically hang a droplet on a fiber in normal gravity conditions without modeling surface tension. Parasitic currents are completely suppressed, allowing to accurately model the evaporation process whatever the droplet size. DropletSMOKE++ shows an excellent agreement with the experimental data in a wide range of operating conditions, for various fuels and initial droplet diameters, both in natural and forced convection. The comparison with the same cases modeled in microgravity conditions highlights the impact of an external fluid flow on the evaporation mechanism, especially at high pressures.Non-ideal thermodynamics for phase-equilibrium is included to correctly capture evaporation rates at high pressures, otherwise not well predicted by an ideal gas assumption. Finally, the presence of flow circulation in the liquid phase is discussed, as well as its influence on the internal temperature field. DropletSMOKE++ will be released as an open-source code, open to contributions from the sci-

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Section: Numerical Results and Discussionsupporting

confidence: 66%

DropletSMOKE++: A comprehensive multiphase CFD framework for the evaporation of multidimensional fuel droplets

Saufi¹,

Frassoldati²,

Faravelli³

et al. 2019

International Journal of Heat and Mass Transfer

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show abstract

“…

whereby u is the velocity, ρ the density, t the time, p the pressure, g the gravitational acceleration, τ the stress tensor, c the specific heat, and k the thermal conductivity. The source term S m of Equation (6) accounts for the phase change, and is given by [ 29 ]:

whereby

. The expression h ( T e − T g ) represents the heat transferred between the droplet and gas, and, thus, h ( T e − T g )/ L v represents the mass transfer per unit area along the interface.…”

Section: Numerical Implementationmentioning

confidence: 99%

“…whereby u is the velocity, ρ the density, t the time, p the pressure, g the gravitational acceleration, τ the stress tensor, c the specific heat, and k the thermal conductivity. The source term S m of Equation ( 6) accounts for the phase change, and is given by [29]:…”

Section: Transport Equationsmentioning

confidence: 99%

Numerical Model to Analyze the Physicochemical Mechanisms Involved in CO2 Absorption by an Aqueous Ammonia Droplet

Galdo

Garcı́a

Lorenzo³

2021

IJERPH

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CO2 is the main anthropogenic greenhouse gas and its reduction plays a decisive role in reducing global climate change. As a CO2 elimination method, the present work is based on chemical absorption using aqueous ammonia as solvent. A CFD (computational fluid dynamics) model was developed to study CO2 capture in a single droplet. The objective was to identify the main mechanisms responsible for CO2 absorption, such as diffusion, solubility, convection, chemical dissociation, and evaporation. The proposed CFD model takes into consideration the fluid motion inside and outside the droplet. It was found that diffusion prevails over convection, especially for small droplets. Chemical reactions increase the absorption by up to 472.7% in comparison with physical absorption alone, and evaporation reduces the absorption up to 41.9% for the parameters studied in the present work.

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“…For the evaporating surface, tracking the droplet fluid-air-interface remains important. In the numerical treatment, an approach of moving mesh incorporating the Arbitrary Lagrangian-Eulerian (ALE) technique becomes fruitful as compared to that utilized volume of fluid technique 18 . Heating and flow are coupled and incompressible flow situation is considered.…”

Section: Mathematical Analysis and Numerical Solutionmentioning

confidence: 99%

Heating Enhancement of a Droplet on a Superhydrophobic Surface

Al‐Sharafi

Yilbaş

Al‐Qahtani

2020

Sci Rep

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Enhancement of heating of a droplet on a hydrophobic surface is investigated. A vertical metal (column) pin is introduced in the droplet and the fluid heating, due to the column pin, is examined. The droplet heating is initiated at the hydrophobic surface and the column pin located in the droplet. The effect of the flow currents on the thermal fields inside the droplet fluid is assessed. An experiment is conducted to assure the velocity simulation results while using the particle image velocimetry (PIV). We demonstrated that the velocity simulations are in good agreement with the data obtained from PIV measurements. Two circulating structures are observed inside the droplet, which are related to the buoyancy and the Marangoni currents. The presence of the column pin changes the number of circulations cells to four inside the droplet. Heated fluid in region of the droplet-solid interface is transferred by the buoyancy current towards the droplet sides and heat diffusion increases temperature rise in the droplet central region. The Nusselt number attains larger values for the droplet with column pin configuration than that of the free droplet, which becomes apparent for the large droplet volumes. The Bond number improves with the presence of the column pin in the droplet; but, the Bond number values become smaller than unity for all the droplets with and without column pin configurations considered. Heating of a water droplet on a hydrophobic plate results in the Marangoni and the buoyancy currents, which generate circulating structures in the droplet. The Bond and the Nusselt numbers are affected by the various parameters, some of which include droplet volume, droplet contact angle, temperature ranges, droplet fluid, and etc. The development of the Marangoni current is associated with the surface tension gradient (γ d dT

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A computational study of droplet evaporation with fuel vapor jet ejection induced by localized heat sources

Cited by 7 publications

References 34 publications

DropletSMOKE++: A comprehensive multiphase CFD framework for the evaporation of multidimensional fuel droplets

DropletSMOKE++: A comprehensive multiphase CFD framework for the evaporation of multidimensional fuel droplets

Numerical Model to Analyze the Physicochemical Mechanisms Involved in CO2 Absorption by an Aqueous Ammonia Droplet

Heating Enhancement of a Droplet on a Superhydrophobic Surface

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