Modified turbulent Prandtl number model for helium–xenon gas mixture with low Prandtl number

Zhou, Baoyao; Ji, Yu; Sun, Jinsheng; Sun, Yuzhu

doi:10.1016/j.nucengdes.2020.110738

Cited by 19 publications

(8 citation statements)

References 30 publications

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“…e applicability of the above model to helium-xenon mixtures has been verified in detail in the literature [23]. Hence, this section mainly focuses on the validation of simulation models for water and air.…”

Section: Validation Of Simulation Modelsmentioning

confidence: 91%

“…erefore, the SST k − ω model is selected for numerical simulations in this study. Additionally, to ensure the validity of numerical calculation, the grid independence verification also has been studied in the literature [23]. e current mesh uses the grid number of 40 × 2000 with the y + of the first grid less than 0.5.…”

Section: Turbulence Modelmentioning

confidence: 99%

“…By considering the wide use of HeXe40 in most schemes [19][20][21][22], numerical investigations on turbulent heat transfer of HeXe40 (Pr � 0.21) in a heated tube are performed by employing the new modified turbulent Prandtl number (Pr t ) model proposed in our previous paper [23]. To better reflect the particularity of low-Pr helium-xenon mixture on the turbulent flow and heat transfer in the near-wall region, a numerical comparison between HeXe40 and air (Pr � 0.71) and liquid water (Pr � 6.99) is conducted.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Investigation on Turbulent Flow and Heat Transfer of Helium-Xenon Gas Mixture in a Circular Tube

Zhou

Han

Sun

et al. 2021

Science and Technology of Nuclear Installations

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Gas-cooled space nuclear reactor system usually utilizes the helium-xenon gas mixture as the working fluid. Since the typical helium-xenon mixture has the Prandtl number of about 0.2, which is lower than that of water and air, the turbulent flow and heat transfer features need to be further investigated among the helium-xenon mixture and other fluids. In the current paper, numerical investigations by ANSYS Fluent are performed on helium-xenon mixture flow (HeXe40, M = 40.0 g/mol, Pr = 0.21), airflow (Pr = 0.71), and water flow (Pr = 6.99) in the circular tube. Direct numerical simulation results of liquid metal flow (Pr = 0.01) are also adopted for comparison. Results show that the dimensionless velocity profile and shear stress in the boundary layer of HeXe40 are close to those of other fluids. The empirical correlations from other fluids can also predict well the friction factor of helium-xenon mixtures. Due to the discrepancy in turbulent heat diffusivity ratio, the dimensionless radial temperature profile and turbulent heat conduction of HeXe40 significantly differ from those of other fluids. The molecular conduction region of HeXe40 develops up to y+ ≈ 30 and extends to the logarithmic region of the flow boundary layer. Moreover, the available experimental Nusselt numbers of helium-xenon mixtures are compared with several convective heat transfer correlations, in which Kays correlation is better.

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Section: Validation Of Simulation Modelsmentioning

confidence: 91%

Section: Turbulence Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical Investigation on Turbulent Flow and Heat Transfer of Helium-Xenon Gas Mixture in a Circular Tube

Zhou

Han

Sun

et al. 2021

Science and Technology of Nuclear Installations

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“…[40] reviewed the experimental data for the properties of dense noble gas mixtures across a pressure range of 0.1-20 MPa and temperature up to 1400 K, summarizing semi-empirical property correlations. Based on the study of Tournier et al [40], a property-calculation code for helium-xenon mixtures was developed, and its accuracy was validated in a previous study [30]. Figure 3 presents the calculation of variations in gas mixture properties with temperature.…”

Section: Theoretical Derivationmentioning

confidence: 99%

“…To better illustrate the difference in convective heat transfer, Fig. 1 presents the temperature profiles of the air, helium-xenon mixture, and liquid mercury in a heated tube [30]. The temperature profile of the liquid metal was flat; however, the temperature distribution of the helium-xenon mixture was similar to that of air and relatively steep near the wall.…”

Section: Introductionmentioning

confidence: 99%

Nusselt number correlation for turbulent heat transfer of helium–xenon gas mixtures

Zhou

Sun

et al. 2021

NUCL SCI TECH

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A gas-cooled nuclear reactor combined with a Brayton cycle shows promise as a technology for high-power space nuclear power systems. Generally, a helium–xenon gas mixture with a molecular weight of 14.5–40.0 g/mol is adopted as the working fluid to reduce the mass and volume of the turbomachinery. The Prandtl number for helium–xenon mixtures with this recommended mixing ratio may be as low as 0.2. As the convective heat transfer is closely related to the Prandtl number, different heat transfer correlations are often needed for fluids with various Prandtl numbers. Previous studies have established heat transfer correlations for fluids with medium–high Prandtl numbers (such as air and water) and extremely low-Prandtl fluids (such as liquid metals); however, these correlations cannot be directly recommended for such helium–xenon mixtures without verification. This study initially assessed the applicability of existing Nusselt number correlations, finding that the selected correlations are unsuitable for helium–xenon mixtures. To establish a more general heat transfer correlation, a theoretical derivation was conducted using the turbulent boundary layer theory. Numerical simulations of turbulent heat transfer for helium–xenon mixtures were carried out using Ansys Fluent. Based on simulated results, the parameters in the derived heat transfer correlation are determined. It is found that calculations using the new correlation were in good agreement with the experimental data, verifying its applicability to the turbulent heat transfer for helium–xenon mixtures. The effect of variable gas properties on turbulent heat transfer was also analyzed, and a modified heat transfer correlation with the temperature ratio was established. Based on the working conditions adopted in this study, the numerical error of the property-variable heat transfer correlation was almost within 10%.

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Numerical and theoretical investigations of heat transfer characteristics in helium–xenon cooled microreactor core

Wang,

Chai,

Guan

et al. 2023

NUCL SCI TECH

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Modified turbulent Prandtl number model for helium–xenon gas mixture with low Prandtl number

Cited by 19 publications

References 30 publications

Numerical Investigation on Turbulent Flow and Heat Transfer of Helium-Xenon Gas Mixture in a Circular Tube

Numerical Investigation on Turbulent Flow and Heat Transfer of Helium-Xenon Gas Mixture in a Circular Tube

Nusselt number correlation for turbulent heat transfer of helium–xenon gas mixtures

Numerical and theoretical investigations of heat transfer characteristics in helium–xenon cooled microreactor core

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