液态金属锂在管道中传热特性的数值模拟研究

Numerical investigation on heat transfer characterization of liquid lithium metal in pipe

液态金属锂是一种具有广阔发展前景的核反应堆冷却剂,但对其传热特性的相关研究尚不多见。本文建立了描述液态锂在直管内传热过程的稳态二维数学模型,并通过数值模拟分析了液态锂的入口速度、入口温度以及壁面热流密度对其传热性能的影响。结果表明,在较高的入口温度下(>1000 K),液态锂相较于液态钠和铅铋合金在传热性能改善方面具有明显的优势。对于出口径向热流模型的机理分析表明,湍流扩散系数与分子扩散系数之比的数值大小沿管道半径方向呈抛物线型分布。提高液态锂进口速度,降低进口温度和降低壁面热流密度可以有效地削弱低普朗特数液态锂径向传热中分子扩散传热的主导作用。该工作对液态锂的传热特性进行了全面的研究,以期其成为一种具有实际应用前景的核反应堆冷却剂。

Liquid Li metal is a promising nuclear reactor coolant;however,relevant research regarding its heat transfer characteristics remains insufficient.In this study,a steady-state two-dimensional mathematical model is established to describe the heat transfer process of liquid Li in a straight pipe.A numerical analysis is conducted to investigate the effects of inlet velocity,inlet temperature,and wall heat flux on heat transfer in liquid Li.The results indicate the advantage of using liquid Li for improving heat transfer at high inlet temperatures(>1000 K)compared with using liquid sodium and lead–bismuth eutectic.Considering the mechanism of the outlet radial heat flow model,the ratio of turbulent to molecular diffusion coefficients presents a parabolic distribution along the radius of the pipe.Increasing the inlet velocity,decreasing the inlet temperature,and decreasing the wall heat flux can effectively weaken the dominant role of molecular heat transfer owing to the low Prandtl number of liquid Li.The heat transfer of liquid Li is investigated comprehensively in this study,and the results provide a basis for the practical application of liquid Li as a promising coolant.