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<p>To enhance the accuracy of turbulence models for high-temperature and high-pressure supercritical CO<sub>2</sub> (sCO<sub>2</sub>) flows far from pseudo-critical temperature, an experimental study, numerical simulation, and theoretical analysis were carried out. The flow and heat transfer characteristics of sCO<sub>2</sub> in a vertical round tube were investigated. A multi-field coupling model was developed with three turbulent models: the Shear Stress Transport (SST) model, Turbulent Kinetic Energy-Specific Dissipation Rate (<i>k</i>-<i>ω</i>), and Turbulent Kinetic Energy-Turbulent Dissipation Rate (<i>k</i>-<i>ε</i>) models. Results show that turbulence models suitable for subcritical states exhibited substantial average discrepancies when applied to sCO<sub>2</sub> turbulent flows far from the pseudo-critical temperature. This caused an excessive prediction of the wall temperature. The value of the turbulent Prandtl number (<i>Pr</i><sub>t</sub>) had a significant impact on the accuracy of the turbulent model. For the sCO<sub>2</sub> turbulent flow that is situated at a significant distance from the pseudo-critical point, by modifying the <i>Pr</i><sub>t</sub>, each of the three turbulent models could precisely forecast the flow dynamics and thermal characteristics of the sCO<sub>2</sub> turbulent fluid. When the pressure and heat fluxes were in the range of 8–20 MPa, and 95–250 kW·m<sup>−2</sup>, the recommended applicable ranges of <i>Pr</i><sub>t</sub> were 0.65–0.7 for the SST model, 0.55–0.6 for the <i>k</i>-<i>ω</i> model, and 0.55–0.6 for the <i>k</i>-<i>ε</i> model. The findings presented here offer a scientific foundation for the practical application of high-heat-flux sCO<sub>2</sub> turbulent flows in engineering.</p>

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Analysis and Optimization of Turbulent Prandtl Number in Supercritical CO2 Turbulent Flow Models Far from Pseudo-Critical Temperature

  • 期刊论文

  • 发表日期：

    2026年4月22日

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  • Binhui Yu,
  • Yanjuan Wang,
  • Shuo Gao,
  • Qibin Liu

摘要

To enhance the accuracy of turbulence models for high-temperature and high-pressure supercritical CO2 (sCO2) flows far from pseudo-critical temperature, an experimental study, numerical simulation, and theoretical analysis were carried out. The flow and heat transfer characteristics of sCO2 in a vertical round tube were investigated. A multi-field coupling model was developed with three turbulent models: the Shear Stress Transport (SST) model, Turbulent Kinetic Energy-Specific Dissipation Rate (k-ω), and Turbulent Kinetic Energy-Turbulent Dissipation Rate (k-ε) models. Results show that turbulence models suitable for subcritical states exhibited substantial average discrepancies when applied to sCO2 turbulent flows far from the pseudo-critical temperature. This caused an excessive prediction of the wall temperature. The value of the turbulent Prandtl number (Prt) had a significant impact on the accuracy of the turbulent model. For the sCO2 turbulent flow that is situated at a significant distance from the pseudo-critical point, by modifying the Prt, each of the three turbulent models could precisely forecast the flow dynamics and thermal characteristics of the sCO2 turbulent fluid. When the pressure and heat fluxes were in the range of 8–20 MPa, and 95–250 kW·m−2, the recommended applicable ranges of Prt were 0.65–0.7 for the SST model, 0.55–0.6 for the k-ω model, and 0.55–0.6 for the k-ε model. The findings presented here offer a scientific foundation for the practical application of high-heat-flux sCO2 turbulent flows in engineering.