Effects of turbulence models on forced convection subcooled boiling in vertical pipe

Zhang, Rui; Cong, Tenglong; Tian, Wenxi; Qiu, Suizheng; Su, G.H.

doi:10.1016/j.anucene.2015.01.039

Cited by 111 publications

(16 citation statements)

References 12 publications

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“…Eulerian-Eulerian twofluid model along with the interphase actions and wall boiling models used in FLUENT has been validated in our previous work (Zhang et al, 2015c). Besides, the sensitivities of the turbulence model, the mesh size and the near wall turbulence treatment have been studied (Krepper and Rzehak, 2012;Zhang et al, 2015b).…”

Section: Implementation Of the Uncertainty Analysismentioning

confidence: 99%

“…According to previous study on turbulence models (Zhang et al, 2015b), the subcooled boiling simulations were carried out with the Realizable k-ε turbulence model and Enhanced wall function based on the grid with near wall cell Y-plus ranging from 20.2 to 33.1. Besides, the inlet boundary was set at the location 10 times upstream of the test section inlet with a fully developed velocity profile to avoid the effects of inlet velocity profile, since there was a long inducer prior to the inlet of heated section to ensure a fully developed flow in the experiment (Bartolomei and Chanturiya, 1967).…”

Section: Implementation Of the Uncertainty Analysismentioning

confidence: 99%

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Investigation on the Subcooled Boiling in Vertical Pipe With Uncertainties From Boundary Conditions by Using FLUENT

Zhang

et al. 2018

Front. Energy Res.

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Subcooled boiling flow taking place in the reactor system plays a critical role in the safety of nuclear power plants. It has been studied by experiments and system codes in the past decades. Now subcooled boiling can be predicted with CFD code based on the Eulerian two-fluid model, with the development in the computational technology and the understanding in the mechanism of two-phase flow. The published works on the validation of CFD code for two-phase flow were carried out based on the deterministic analysis by comparing the calculated and experimental nominal inputs and outputs, which is not sufficient for code validation since it didn't consider the inevitable uncertainty in the experiment measurements. In the current work, subcooled boiling was predicted by using a CFD code, FLUENT, with consideration of the uncertainties of boundary conditions. The resultant parameters with uncertainties were compared to the experiment data for validation purpose. Confidence intervals of the two-phase parameters were predicted. Besides, correlations between the boundary conditions and the outputs were analyzed.

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Section: Implementation Of the Uncertainty Analysismentioning

confidence: 99%

Section: Implementation Of the Uncertainty Analysismentioning

confidence: 99%

Investigation on the Subcooled Boiling in Vertical Pipe With Uncertainties From Boundary Conditions by Using FLUENT

Zhang

et al. 2018

Front. Energy Res.

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“…According to the literature, and specially the study of Zhang et.al [25] , the k − ε realizable turbulence model is used in this study. In modeling subcooled flows, the turbulent equations only for liquid phase by adding terms for bubble-induced turbulence, and determine the effect of turbulence on the vapor bubbles by introducing a force in the momentum equations.…”

Section: Turbulence Modelmentioning

confidence: 99%

“…One of the important steps in two-phase turbulent flow boiling CFD simulation is choosing a suitable turbulent model. The effect of different turbulent models (k-ε model and k − ω model) on subcooled flow boiling simulation in vertical tube with FLUENT 14.5 code was studied by Zhang.et.al [25] . They employed a two-fluid model coupled with RPI wall boiling model and studied performances of different turbulent models, wall functions and two-phase turbulence treatments based on four sets of grids.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of flow boiling heat transfer in helically coiled tube under constant heat flux

Abdous

Holagh

Saffari

2018

TSE

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Numerical study of subcooled and saturated flow boiling in the curved and helically coiled tubes in presence of phase change is one of the challenging area of CFD studies. In this paper, the CFD modeling of the nucleate and convective flow boiling in the small helically coiled tube at low vapor quality (up to the 18.93 percent) region is studied. A proper Eulerian-based mathematical model is used for interphase exchange forces and heat transfer between two phases in CFD modeling using Bulk boiling model. The results show that, the inner and the bottom wall of the helically coiled tube have the lowest and the highest heat transfer coefficient, respectively. The effect of change in coil diameter, helical pitch and tube diameter is investigated on the counters of vapor volume fraction. It is seen that at low vapor quality flows, the heat transfer coefficient is enhanced by decreasing in coil diameter, tube diameter and increasing in coil pitch of helically coiled tube.

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“…Thomas et al [8] set the bubble diameters as a constant in the whole computation domain and tuned this value for different test conditions based on experience. Zhang et al [3] and Krepper et al [1] defined the bubble diameter as a function of localized fluid subcooling in each computational cell, which was better than Thomas et al's [8] work, but it still cannot present the polydisperse characteristics of bubble size. In the recent work on bubbly flow simulation, the bubble size distribution has been considered by using the PBM or the MUSIG models [9,10].…”

Section: Eulerian Two-fluid Modelmentioning

confidence: 99%

Numerical Study of Bubble Coalescence and Breakup in the Reactor Fuel Channel with a Vaned Grid

Cong

Zhang

2018

Energies

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The characteristics of bubbles of different sizes in fuel assembly are vital to two-phase flow resistance and heat transfer capacity. However, due to the swirl flow caused by the mixing vane, bubbles can crowd at the heated surface, which may anticipate the occurrence of departure from nucleation boiling. In the current work, the adiabatic two-phase flow in a simplified fuel assembly was analyzed by using the Eulerian two-fluid model and the MUSIG (MUltiple SIze Group) model. This computational domain consists of two coolant channels and two sets of vaned spacers, with three sets of periodic boundary conditions at the side faces of the domain. The distributions of vapor phase and bubble diameters were obtained, based on which the effects of mixing vanes on the bubble characteristics were analyzed. Vapor phase crowded at the rod surface in the higher inlet vapor fraction case, but crowded in the channel center in the lower inlet vapor fraction cases. This work can be used as a reference for the design of mixing vanes to avoid the anticipation of departure of nucleation boiling that may be caused by unreasonable design.

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Effects of turbulence models on forced convection subcooled boiling in vertical pipe

Cited by 111 publications

References 12 publications

Investigation on the Subcooled Boiling in Vertical Pipe With Uncertainties From Boundary Conditions by Using FLUENT

Investigation on the Subcooled Boiling in Vertical Pipe With Uncertainties From Boundary Conditions by Using FLUENT

Numerical investigation of flow boiling heat transfer in helically coiled tube under constant heat flux

Numerical Study of Bubble Coalescence and Breakup in the Reactor Fuel Channel with a Vaned Grid

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