Lead-cooled fast reactor (LFR) is one of the most promising reactor types among the fourth-generation nuclear reactors. However, due to spatial constraints within the LFR system, traditional rectangular heat exchangers face practical limitations. By adjusting the layout of the heat exchanger from a rectangular to a curved arrangement, it is possible to achieve a coordinated layout with other equipment in the lead-cooled fast reactor system, effectively addressing the issue of limited space.

This study aims to analyze the heat transfer performance of curved heat exchangers under various boundary conditions and propose a compact curved heat exchanger suitable for the limited space of lead-cooled fast reactors.

Firstly, a curved heat exchanger (CHX) suitable for limited spaces was designed. Then, computational fluid dynamics (CFD) software Fluent was used to analyze the performance of designed CHX with coupled heat transfer between lead-bismuth eutectic (LBE) and SCO₂. Subsequently, the coupled heat transfer performance of the CHX was analyzed by changing the inlet parameters of the fluid. Finally, the effect of geometric parameters on the heat transfer performance of the heat exchanger was analyzed by changing the curvature in the ranger of 0°~2°.

Computation results show that the thermal resistance primarily resides on the SCO₂ side during the coupled heat transfer process between LBE and SCO₂, and the heat transfer coefficient is more sensitive to changes in the mass flow rate in the SCO₂ side. The curvature of the CHX has minimal impact on the heat transfer performance, indicating that CHXs exhibit strong adaptability to spatial constraints in practical conditions.

The results of this study provide valuable references for the design of curved heat exchangers in future lead-cooled fast reactors.