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基于大型熔融池换热特性试验台架COPRA,分别采用水和非共晶摩尔比例20%NaNO_3-80%KNO_3混合物作为熔融物模拟物,进行熔融池换热特性试验研究。熔融池瑞利数Ra′可达到1016量级,与反应堆真实情况下的量级一致。试验对比了水试验和熔盐试验得到的熔融池温度场分布和壁面热流密度分布。结果表明,熔融物硬壳的形成对熔融池换热特性产生了明显影响。试验拟合得到了熔融池换热特性关系式,其中热流密度关系式与国际上其他试验得到的结果符合得较好。在同等Ra′量级下,COPRA试验得到的熔融池向下封头壁面的传热量较国际上其他试验的结果低。
Based on the COPRA test bench for the large-scale heat transfer characteristics of molten pool, the mixture of water and non-eutectic 20% NaNO 3 - 80% KNO 3 was used as the melt simulant to study the heat transfer characteristics of the molten pool. The melting pool Rayleigh number Ra ’can reach the magnitude of 1016, which is the same order of magnitude as the real reactor. The temperature field distribution and wall heat flux density distribution of the molten pool obtained from the water test and molten salt test were compared. The results show that the formation of melt crust has a significant impact on the heat transfer characteristics of the molten pool. The relationship between the heat transfer characteristics of the molten pool was obtained by experimental fitting. The heat flux density was in good agreement with the results from other international experiments. At the same Ra ’level, the heat transfer capacity of the molten pool down to the head surface of the COPRA test is lower than that of other international tests.