Numerical Analysis of Conjugate Heat Transfer of Supercritical CO₂ and Pb-Bi in Tube-in-Tube Channels

This work presents a numerical analysis of conjugate heat transfer in an annular channel with turbulence models for supercritical CO₂ (tube side) and Pb-Bi (annular side) as working fluids to understand the impact of flow constraints and heat transfer. By using the Navier-Stokes formulation and the energy equation clarifying concurrent flow buildup and conjugate heat transmittance in tubes, several turbulent Prandtl models were solved numerically. The turbulent Prandtl number Pr_t of Pb-Bi was used to refine the consistency of the arithmetical simulation. By comparing Pr_t, temperature fluctuation, and heat flux density, it was concluded that the existing Pr_t model should be used with caution in the numerical calculation of liquid metals having low Pr. The heat transfer and flow phenomena at different Pr_t values are significantly different.