Abstract The natural convection thermal behavior with high Rayleigh number was important in many industrial situations accompanied by internal heating, strong turbulence and solidification process. Experiments were carried out to investigate natural convection thermal characteristics in internally heated pool. Both water and nitrate were selected as simulant materials. The pool temperature along height, heat flux and crust thickness along polar angle were obtained from experiments. The effects of heating power density, pool height, crust solidification, cooling boundary were investigated. Moreover, the geometry effect of 2D and 3D were investigated based on the CFD simulation. The crust formation resulted in higher heat transfer on top with the largest heat flux ratio of 2.4 in nitrate cases and only 1.9 in water cases, indicating that the relationship without solidification applied in system codes may lead to lower peak heat flux at pool top. The Nudn increased exponentially and the Nudn from nitrate tests were higher than those from water tests with larger temperature gap Tmax-Tint. The cooling effectiveness of 3D hemispherical pool was 1.5 times that of 2D slice pool. However, the Nudn from hemispherical simulation was 24.06% higher than the COPRA relation prediction. The application of two-dimensional results needs consideration of geometry extrapolation for further application.

中文翻译：

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内温水池自然对流热特性参数分析

摘要 具有高瑞利数的自然对流热行为在许多伴随内部加热、强湍流和凝固过程的工业情况中是重要的。进行了实验以研究内部加热池中的自然对流热特性。选择水和硝酸盐作为模拟材料。通过实验获得沿高度的池温、沿极角的热通量和地壳厚度。研究了加热功率密度、熔池高度、结壳凝固、冷却边界的影响。此外，基于 CFD 模拟研究了 2D 和 3D 的几何效果。地壳形成导致顶部传热更高，硝酸盐情况下的最大热通量比为 2.4，水情况下仅为 1.9，表明在系统代码中应用没有凝固的关系可能会导致池顶部较低的峰值热通量。Nudn 呈指数增加，硝酸盐试验的 Nudn 高于温差 Tmax-Tint 较大的水试验的 Nudn。3D 半球形水池的冷却效率是 2D 切片水池的 1.5 倍。然而，来自半球模拟的 Nudn 比 COPRA 关系预测高 24.06%。二维结果的应用需要考虑几何外推以供进一步应用。3D 半球形水池的冷却效率是 2D 切片水池的 1.5 倍。然而，来自半球模拟的 Nudn 比 COPRA 关系预测高 24.06%。二维结果的应用需要考虑几何外推以供进一步应用。3D 半球形水池的冷却效率是 2D 切片水池的 1.5 倍。然而，来自半球模拟的 Nudn 比 COPRA 关系预测高 24.06%。二维结果的应用需要考虑几何外推以供进一步应用。