Experimental Study on Liquid Lead-bismuth Heat Transfer Characteristic in Rod Bundle Channel of Hexagonal Assembly

To explore the flow and heat transfer characteristics of liquid lead-bismuth eutectic (LBE) in the hexagonal rod bundle assembly, an experiment on liquid lead-bismuth heat transfer was carried out at 0.250 kPa of operation pressure, 200-300 ℃ of inlet temperature, 0.47 071.48 W·m-2 of heat flux, 0.4 kg·s-1 of mass flow rate, and 300-600 of Peclet number (Pe). The experimental facilities and operating conditions were introduced in detail, and the uncertainty of this experiment was analyzed to ensure the accuracy of the results. The heat transfer characteristics of liquid lead-bismuth in the rod bundle under different measuring points, heat flux, and inlet temperature were analyzed, and the relevant experimental results were obtained. The simplified Reynolds averaging equation of turbulent flow and heat transfer were also introduced to analyze the characteristics of LBE based on experimental results. The experimental data show that different inlet temperatures have little effect on the flow and heat transfer characteristics of LBE. At high Pe operating condition, the difference of heat transfer of LBE under different wall heat fluxes is also not significant. Based on the experimental measurements of flow and heat transfer characteristics in the rod bundle channel, the flow and heat transfer empirical relations of liquid metal in the world were calculated and evaluated. The results show that the relation of Mikityuk has the best prediction to this experiment which is introduced in this article. This is because that Mikityuk sorts and analyzed the previous heat transfer relations for liquid metals, and obtains a new form to describe the heat transfer relations for liquid metals. Therefore, a new heat transfer relation of LBE was fitted with reference to the basic form of relation of Mikityuk. The applicability and reliability of the new empirical relation were checked out and evaluated by the experimental data of Karlsruhe Institute of Technology (KIT) in Germany under 19 rods bundle operating condition. The calculation results show that the deviation of the new empirical relation for the KIT 19 rod bundle is ±20%, which proves that the new empirical relation has the high applicability and reliability. Finally, based on the similarity principle of fluid mechanics, the reason for the deviation between the empirical relationship fitted in this article and the KIT 19 rod bundle experiment data was also analyzed. The experimental data and the new empirical relation in this article can provide the references and technical supports for the design and research of flow and heat transfer characteristics of LBE in rod bundle channel of hexagonal assembly in the liquid metal cooled reactor in China