Abstract Two-phase thermosyphons are very efficient devices with excellent temperature uniformity due to their high thermal conductance characteristics. Large temperature gradients observed in sodium two-phase thermosyphons under steady state operation is a clear sign of design flaws. Bad designs may lead to the decrease of the device thermal performance, as well as to significant thermal stresses in the thermosyphon walls, affecting the operation life and promoting leakages. This study presents steady state theoretical models concerning the startup limit, the continuum limit and the temperature distribution along the condenser. The models proposed in this study are based on the analogy between a two-phase thermosyphon and a thermal fin, where a modified Biot number is proposed to predict the vapor flow behavior inside two-phase thermosyphons. The results obtained are in good agreement with experimental data, showing that the proposed models can be used for the design of reliable and safe high temperature two-phase thermosyphons .

中文翻译：

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高温热虹吸管的启动和连续极限的修正 Biot 数模型

摘要 两相热虹吸管具有高热导特性，是一种非常高效的装置，具有良好的温度均匀性。在稳态操作下在钠两相热虹吸管中观察到的大温度梯度是设计缺陷的明显迹象。糟糕的设计可能会导致设备热性能下降，以及在热虹吸管壁中产生显着的热应力，从而影响使用寿命并促进泄漏。本研究提出了关于启动极限、连续极限和沿冷凝器的温度分布的稳态理论模型。本研究中提出的模型基于两相热虹吸管和散热片之间的类比，其中提出了修改的 Biot 数来预测两相热虹吸管内的蒸汽流动行为。