Abstract As an efficient approach of heat transfer, condensation is applied to the passive containment cooling system in the nuclear power plant for a fast export of heat. However, the existence of noncondensable gases in the containment will inhibit condensation heat transfer then increase the risks to the nuclear power reactors. In order to search effective methods to improve the condensation heat transfer, this study investigated condensation in the presence of NCG experimentally focusing on two aspects: (i) to search heat transfer characteristics of filmwise condensation; (ii) to evaluate possible heat transfer enhancement taken by dropwise condensation. For the first one, a new numerical model was developed to quantitatively analyze the thermal resistance distribution in the condensation process. The result indicated that the effect of various parameters on condensation heat transfer depended on the variation of both the thermal resistances of the liquid film and NCG accumulation layer. It provided a reliable explanation for the divergence of early perspectives around the effects on condensation heat transfer of subcooling or system pressure. For the second one, dropwise mode was proved to significantly enhance the condensation heat transfer when the noncondensable gas existed. However, this heat transfer enhancement is limited by the NCG accumulation in the gaseous mixture.

中文翻译：

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NCG存在下冷凝传热特性的热阻分析实验研究

摘要 作为一种有效的传热方法，在核电站被动安全壳冷却系统中采用冷凝技术以实现热量的快速输出。然而，安全壳中不凝气体的存在会抑制冷凝传热，从而增加核动力反应堆的风险。为了寻找改善冷凝传热的有效方法，本研究从两个方面对NCG存在下的冷凝进行了实验研究：(i)寻找薄膜状冷凝的传热特性；(ii) 评估滴状冷凝可能进行的传热增强。对于第一个，开发了一种新的数值模型来定量分析冷凝过程中的热阻分布。结果表明，各种参数对冷凝传热的影响取决于液膜和NCG积聚层热阻的变化。它为有关过冷或系统压力对冷凝传热影响的早期观点的分歧提供了可靠的解释。对于第二个，当不凝气体存在时，逐滴模式被证明显着增强了冷凝传热。然而，这种传热增强受到气体混合物中 NCG 积累的限制。它为有关过冷或系统压力对冷凝传热影响的早期观点的分歧提供了可靠的解释。对于第二个，当不凝气体存在时，逐滴模式被证明显着增强了冷凝传热。然而，这种传热增强受到气体混合物中 NCG 积累的限制。它为有关过冷或系统压力对冷凝传热影响的早期观点的分歧提供了可靠的解释。对于第二个，当不凝气体存在时，逐滴模式被证明显着增强了冷凝传热。然而，这种传热增强受到气体混合物中 NCG 积累的限制。