Numerical study of turbulent heat transfer of annular fuel assembly in a sodium-cooled fast reactor by a SST k-ω-k_θ-ε_θ model

ABSTRACT

The annular fuel has two cooling surfaces inside and outside, which can fully take away the heat of the fuel assemblies. It is urgent to conduct research on sodium-cooled fast reactor annular fuel assemblies. The Prandtl number Pr of liquid sodium is much less than 1 (Pr ˂˂ 1). The problem is that using the traditional constant turbulent Prandtl number Pr_t of 0.85 ~ 0.9, which will greatly affect the accuracy of the numerical prediction of the thermal-hydraulic properties of liquid sodium. In order to address this issue, the turbulent heat transfer characteristics of the bare and wire spacers 7-pin annular fuel assembly for a sodium-cooled fast reactor are investigated by a SST k-ω-k_θ-ε_θ model. The open-source CFD software OpenFOAM is used for this calculation. In order to verify the validity of the present calculation method, some classical liquid metal heat transfer correlations are used to compare and analyze the results of the present calculation method (k_θ-ε_θ model), the results of the Reynolds analogy hypothesis (Pr_t = 0.85 model), and the results of the turbulent Prandtl number correlation (Pr_t = kays model). It is shown that the SST k-ω-Pr_t = 0.85 model overestimates the Nusselt number Nu of the annular fuel assembly. The SST k-ω-k_θ-ε_θ model agrees well with the SST k-ω-Pr_t = Kays model of the bare and wire spacers 7-pin annular fuel assembly . It suggests that the numerical calculation results of the SST k-ω-k_θ-ε_θ model are reliable in both the simple and complex fuel assembly models. In brief, the SST k-ω-k_θ-ε_θ model is more capable of predicting the turbulent heat transfer characteristics of the bare and wire spacers 7-pin annular fuel assembly in sodium-cooled fast reactors. In addition, the thermal-hydraulic characteristics of annular fuel assemblies with wire spacers for sodium-cooled fast reactors have been investigated. This research can provide a reference for the study of turbulent heat transfer characteristics of annular fuel assemblies in sodium-cooled fast reactor.

KEYWORDS:

• Sodium-cooled fast reactor
• annular fuel assembly
• SSTk-ω-k_θ-ε_θ model
• OpenFOAM

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by the China Postdoctoral Science Foundation [Grant No. 2023M731458], the Science and Technology Program of Gansu Province, China [Grant No. 23JRRA1099], and the National Natural Science Foundation of China [Grant No. 12122512 and 12005317].