A New Correlation for Predictions of Heat Transfer of Lead-Bismuth Eutectic in Circular Tubes

Liquid lead or lead-bismuth eutectic has good thermal physical properties, neutron performances, and natural circulation capacity. It is the first choice of coolant material for the lead-based fast reactor (LFR). However, there is a fundamental problem, heat-transfer characteristics and quantitative relationship of liquid lead and lead-bismuth eutectic, to be solved in the process of thermal-hydraulic design and safety analysis code development of lead-based fast reactor. The existing correlations are mostly fitted by the experimental data under specific conditions and the applicability is poor in a wide range of parameters, which affects the accuracy of thermal-hydraulic design and safety analysis results. Therefore, it is a necessity to establish experimental databases and correlation databases to obtain a more accurate heat transfer correlation of liquid lead and bismuth eutectics within a wider range of parameters. This paper reviews the typical theoretical and experimental studies on the heat transfer characteristics of liquid lead and lead-bismuth eutectics in the recent 70 years, and an experimental database based on the heat transfer experimental data in the published literature is established, which data points include a wide range of thermodynamic parameters — inner diameter ranging from 9.00 to 16.56 mm, temperature from 250.0 to 412.80 °C, heat fluxes from 20.0 to 12900.0 kW/m2, and mass fluxes from 0 to 12.0 kg/m2s. Based on the database, the typical heat transfer correlations of liquid lead and lead-bismuth eutectics are evaluated and analyzed, and a new heat transfer correlation is developed, its suitable range is 100 < Pe < 5800. The results show that the mean absolute relative error of the new correlation is 16.64%, the average relative error is 0.74%, the standard deviation is 4.37%, and the error of 65.27% of the total data points is within ± 20%. Therefore, the heat-transfer correlation proposed in this study can well predict the heat-transfer coefficient of high-temperature liquid lead or lead-bismuth eutectic in the tube.