Status and perspectives of turbulent heat transfer modelling in low-Prandtl number fluids

Shams, A.; Santis, Andrea De; Koloszar, Lilla; Ortiz, Agustín Villa; Narayanan, Chidambaram

doi:10.1016/j.nucengdes.2019.110220

Cited by 33 publications

(17 citation statements)

References 18 publications

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“…On the other hand, in low Prandtl-number fluids the contribution of the molecular thermal conduction to the total heat transfer is higher than other streams. Since having high thermal conductivity coefficients, thus very low molecular Pr that result in a much thicker thermal boundary layer as compared to the hydrodynamic one, it becomes difficult to correlate them concurrently with moderate and high Prandtlnumber fluids [6,38].…”

Section: Variablesmentioning

confidence: 99%

Application of the ‘Nusselt-Equation Simulated Evolution Method’ in Forced Convective Heat Transfer Modeling

Sánchez-Escalona¹,

Camaraza-Medina²,

Retirado-Mediaceja³

et al. 2021

IJDNE

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Reliability of heat exchangers thermal analysis strongly depends on the equations selected to determine local convective heat transfer coefficients. Chosen analogy among momentum, heat and mass transfer also plays a remarkable role. Within this context, the aim of the study was to validate a novel approach to obtain mean forced convective film coefficients under single-phase non-laminar fluid flow conditions, inside tubes. It relied on a comprehensive Nusselt-number equation that is able to evolve into different functional forms according to Reynolds-Colburn, Prandtl and von Karman analogies. Parameters estimation was carried out through Genetic Algorithms. Applied experimental database was numerically obtained by Taler by solving the energy conservation equation for fully developed turbulent flow in tubes with constant wall heat flux. Application of the method provided a new correlation, valid for 0.1 ≤ ≤ 10 3 and 3 × 10 3 ≤ ≤ 10 6 . Besides attaining a better fit to the experimental data as compared to benchmark expressions, it correlated very well with the results of reference models (Skupinski, Seban & Shimazaki, Gnielinski, Camaraza-Medina, Petukhov, and Sandall). The first assessment provided mean and maximum relative errors of 2.41% and 19.45%, respectively, while the second comparison resulted in deviations over the Nusselt number up to 20% in 92.59% of the data points. The implemented solution overcomes the drawbacks of non-linear and symbolic regression methods by allowing evolution of the regression function within a controlled mathematical environment. Future model improvements should investigate different fitting-intervals along with higher turbulence regions.

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Section: Variablesmentioning

confidence: 99%

Application of the ‘Nusselt-Equation Simulated Evolution Method’ in Forced Convective Heat Transfer Modeling

Sánchez-Escalona¹,

Camaraza-Medina²,

Retirado-Mediaceja³

et al. 2021

IJDNE

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“…Improvements on modelling and simulation have been proposed and tested on different simple test cases [19]. An update of the ongoing model evaluation and development is reported in [20].…”

Section: Liquid Metal Heat Transfermentioning

confidence: 99%

“…Finally, [20] summarizes the latest developments with respect to advanced turbulent heat flux model developments. In the frame of the SESAME project, new reference data are assessed for a variety of advanced turbulent heat flux models, i.e.…”

Section: Liquid Metal Heat Transfermentioning

confidence: 99%

SESAME project: advancements in liquid metal thermal hydraulics experiments and simulations

Tarantino

Roelofs

Shams

et al. 2020

EPJ Nuclear Sci. Technol.

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Liquid metal cooled reactors are envisaged to play an important role in the future of nuclear energy production because of their possibility to use natural resources efficiently and to reduce the volume and lifetime of nuclear waste. Sodium and Liquid lead (-alloys) are considered the short and long term solution respectively, as coolant in GEN-IV reactor. Thermal-hydraulics of liquid metals plays a key role in the design and safety assessments of these reactors. Therefore, this is the main topic of a large European collaborative program (the Horizon 2020 SESAME) sponsored by the European Commission. This paper will present the progress in the project with respect to liquid metal cooled reactor thermal-hydraulics (liquid metal heat transfer, fuel assembly thermal-hydraulics, pool thermal-hydraulics, and system thermal-hydraulics). New reference data, both experimental and high-fidelity numerical data is being generated. And finally, when considering the system scale, the purpose is to validate and improve system thermal-hydraulics models and codes, but also to further develop and validate multi-scale approaches under development.

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“…The particularity of flow and heat transfer for low-Pr fluids has been widely concerned [18][19][20]. However, most studies on this issue have mainly focused on liquid metals (Pr % 0.01), where many heat transfer correlations for liquid metals were proposed [21][22][23].…”

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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Status and perspectives of turbulent heat transfer modelling in low-Prandtl number fluids

Cited by 33 publications

References 18 publications

Application of the ‘Nusselt-Equation Simulated Evolution Method’ in Forced Convective Heat Transfer Modeling

Application of the ‘Nusselt-Equation Simulated Evolution Method’ in Forced Convective Heat Transfer Modeling

SESAME project: advancements in liquid metal thermal hydraulics experiments and simulations

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

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