An explicit expression of the empirical factor in a widely used phase change model

Chen, Guang; Nie, Taotao; Yan, Xiaohong

doi:10.1016/j.ijheatmasstransfer.2019.119279

Cited by 28 publications

(10 citation statements)

References 24 publications

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“…Similar to the surface tension force (see (7)), the evaporation rate, Γ, must be expressed as a volumetric source term distributed over the thin zone to which the interface is smeared in the VOF model (bulk boiling of water is not possible in this approach). Here, we use the evaporation model proposed in [30] (with slight modifications [25]), containing no user-defined constants:…”

Section: Statement Of the Problemmentioning

confidence: 99%

Numerical Modeling of Water Jet Plunging in Molten Heavy Metal Pool

Yakush,

Sivakov,

Melikhov

et al. 2023

Mathematics

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The hydrodynamic and thermal interaction of water with the high-temperature melt of a heavy metal was studied via the Volume-of-Fluid (VOF) method formulated for three immiscible phases (liquid melt, water, and water vapor), with account for phase changes. The VOF method relies on a first-principle description of phase interactions, including drag, heat transfer, and water evaporation, in contrast to multifluid models relying on empirical correlations. The verification of the VOF model implemented in OpenFOAM software was performed by solving one- and two-dimensional reference problems. Water jet penetration into a melt pool was first calculated in two-dimensional problem formulation, and the results were compared with analytical models and empirical correlations available, with emphasis on the effects of jet velocity and diameter. Three-dimensional simulations were performed in geometry, corresponding to known experiments performed in a narrow planar vessel with a semi-circular bottom. The VOF results obtained for water jet impact on molten heavy metal (lead–bismuth eutectic alloy at the temperature 820 K) are here presented for a water temperature of 298 K, jet diameter 6 mm, and jet velocity 6.2 m/s. Development of a cavity filled with a three-phase melt–water–vapor mixture is revealed, including its propagation down to the vessel bottom, with lateral displacement of melt, and subsequent detachment from the bottom due to gravitational settling of melt. The best agreement of predicted cavity depth, velocity, and aspect ratio with experiments (within 10%) was achieved at the stage of downward cavity propagation; at the later stages, the differences increased to about 30%. Adequacy of the numerical mesh containing about 5.6 million cells was demonstrated by comparing the penetration dynamics obtained on a sequence of meshes with the cell size ranging from 180 to 350 µm.

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Section: Statement Of the Problemmentioning

confidence: 99%

Numerical Modeling of Water Jet Plunging in Molten Heavy Metal Pool

Yakush,

Sivakov,

Melikhov

et al. 2023

Mathematics

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“…Note that a smaller assumed β may lead to inaccurate calculation results, while a larger value may also cause significant divergence. Previous studies pointed out that the appropriate value of β is influenced by various factors such as the fluid properties, geometry, boundary conditions and even mesh size [31,32]. Table 2 summarizes the recent literature [13,15,16,21,22,27,[33][34][35][36] on numerical simulation of flow condensation using VOF model coupled with Lee's phase change model.…”

Section: Phase Change Modelmentioning

confidence: 99%

Numerical Study on R32 Flow Condensation in Horizontally Oriented Tubes with U-Bends

et al. 2022

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In this paper, the flow condensation heat transfer characteristics of R32 in a horizontally oriented tube with a horizontal U-bend (HUB tube) and a horizontally oriented tube with a vertical U-bend (VUB tube) were numerically investigated. The volume of fluid (VOF) multiphase model with the mass transfer assumption by Lee is adopted to simulate the flow condensation behavior of R32, which are validated by well-known empirical correlations. The influence of structural parameters, mass flux and vapor quality on the heat transfer coefficient (HTC) and liquid film distribution is investigated. Meanwhile, the local liquid film thickness (LLFT) and local heat transfer coefficient (LHTC) are also depicted. The phase transition at the U-bend section is captured. Results show that the U-bend has remarkable disturbance on the flow pattern and LHTC due to the effect of centrifugal force where the LLFT is changed, inducing strong secondary flow. The LHTC is increased by a maximum of 8.47% and 11.86% in VUB tube and HUB tube, respectively, when compared to the case in a horizontally straight oriented tube at the same operating conditions.

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“…The phase change model proposed by Lee is the most commonly used. Mass transfers are given by the following equations [6], [8], [11], [13]: where 𝑚𝑚̇𝑙𝑙 𝑙𝑙 , 𝑚𝑚̇𝑙𝑙 𝑙𝑙 are intensities of mass transfer due to evaporation and condensation, respectively (kg.s -1 .m -3 ); 𝛼𝛼 𝑙𝑙 , 𝛼𝛼 𝑙𝑙 are phase volumes fractions (−); 𝜌𝜌 𝑙𝑙 , 𝜌𝜌 𝑙𝑙 are densities of liquid and vapor (kg.m -3 ); 𝑇𝑇 𝑙𝑙 is the temperature of liquid (K); 𝑇𝑇 𝑠𝑠𝑠𝑠𝑠𝑠 is the temperature of saturation (K) and 𝑇𝑇 𝑙𝑙 is temperature of vapor (K). 𝜆𝜆 𝑐𝑐 denotes the mass transfer intensity factor with unit s -1 .…”

Section: Lee Modelmentioning

confidence: 99%

Correlation Coefficients in Lee’s Model of Multiphase Flows

et al. 2022

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Multiple technical and biological systems exhibit multiphase flow phenomena. The demands for accurate calculations of the physical phenomena that occur in engineering technologies have increased along with their rapid advancement. However, it is very hard to identify two- and multi-phase flow through experimental measurements, as a result, in addition to experimental measurements, numerical simulations are also performed, which can help improve our physical understanding of the complex phenomenon of phase transformations. The goal of numerical simulations of phase changes is to precisely simulate the real progress and experiment. These simulations operate on the basis of physical principles and correlation coefficients of phase changes. These correlation coefficients have a different range of values. The examination of the Lee model's correlation coefficients from the ANSYS Fluent environment, which is now the most popular for multiphase flow simulations, is the subject of the article that is being given. In this article is also described and tested the numerical simulation of interphase mass transport in a closed space. Research background: The article is focused on the problematics of multiphase flows. In ANSYS Fluent, there are many types of models, which are used for the numerical simulations of this phenomena. In models are included correlation parameters, which are specific for every single situation and are within the given ranges. This paper is about the Lee model, which correlation coefficients are in the range from 10-3 to 102. Purpose of the article: A detailed description of Lee's model with its testing on a heat pipe in the ANSYS Fluent program with determined correlation coefficients. Methods: The use of CFD simulation of multiphase flow to determine correlation coefficients. Findings & Value added: Testing the correlation coefficients of Lee's model and finding their appropriate values for the given situation.

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An explicit expression of the empirical factor in a widely used phase change model

Cited by 28 publications

References 24 publications

Numerical Modeling of Water Jet Plunging in Molten Heavy Metal Pool

Numerical Modeling of Water Jet Plunging in Molten Heavy Metal Pool

Numerical Study on R32 Flow Condensation in Horizontally Oriented Tubes with U-Bends

Correlation Coefficients in Lee’s Model of Multiphase Flows

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