Lead cooled fast reactor and supercritical carbon dioxide(S-CO_2) Brayton cycle are considered to be one of the most promising power generation systems because of their high thermal efficiency and compact design. Heat transfer occurs between lead bismuth alloy(Pb/Bi) and S-CO_2 in the intermediate heat exchanger. However

the turbulent transport characteristics and coupling heat transfer behavior of Pb/Bi and S-CO_2 are different from that of conventional fluids. The conventional turbulence prediction models can not accurately predict the coupling heat transfer performance. In order to obtain an accurate prediction model and reveal the rules of the heat transfer between Pb/Bi and S-CO_2

the applicability of the exsiting turbulent Prandtl models of Pb/Bi and S-CO_2 is compared and analyzed at first. It finds that Tang's Prandtl model on the S-CO_2 side and Cheng Tak's Prandtl model on the Pb/Bi side can obtain accurate results. Then

the coupling heat transfer models for Pb/Bi and S-CO_2 are further analyzed and verified

the simulation results are in good agreement with the experimental data. The effects of Reynolds number and inlet temperature on the coupling heat transfer performance between S-CO_2 and Pb/Bi are fully discussed. It finds that the heat resistance of the casing heat exchanger mainly exists on the S-CO_2 side

increasing the flow rate of S-CO_2 can quickly improve the heat transfer performance

and the heat transfer capacity of the heat exchanger is greatly enhanced when the main temperature of S-CO_2 is in the quasi critical zone.