Heat pipe cooled reactor (HPR) is considered as an excellent candidate for space power systems. As a core cooling method, the operational characteristics of high-temperature heat pipes need to be researched. In this paper, the heat transfer performance of potassium heat pipes (Φ30mm × 800 mm) is studied experimentally. The thermal behavior of heat pipe is tested under various conditions, including heating power (0.2–4 kW), air/water cooling method, inclination angle (0–90°), and filling ratio (20% and 100% of void in wick). And the characteristics of heat transfer limits are analyzed, consisting of dryout, entrainment, and sonic limit. The results show heating power is beneficial to heat transfer within the capillary limit. However, overheating occurs when heating power exceeds the capillary limit. The inclination angle has a strong effect on the thermal efficiency of heat pipe for the competition between gravity and entrainment, and the angle of 30° corresponds to the best thermal performance. Sonic limit and entrainment limit are estimated with a relative error of 38.7% and 17.9%. Dryout is divided into local dryout (<200 °C/m) and integral dryout (>200 °C/m). It is concluded that the high filling ratio (100%) and the small inclination angle (30°) are helpful to realize the optimal thermal performance. This work makes it possible to validate the operation of a high-temperature heat pipe and provides a reference for the design and application of HPR.

热管冷却反应堆（HPR）被认为是空间动力系统的理想选择。作为核心冷却方法，需要研究高温热管的工作特性。本文对Φ30mm×800mm钾热管的传热性能进行了实验研究。在各种条件下测试热管的热性能，包括加热功率（0.2–4 kW），空气/水冷却方法，倾斜角度（0–90°）和填充率（灯芯中空隙的20％和100％） ）。并分析了传热极限的特征，包括变干，夹带和声极限。结果表明，加热功率有利于毛细管极限内的热传递。但是，当加热功率超过毛细管极限时，会发生过热。倾斜角对热管的热效率具有很强的影响，以克服重力和夹带之间的竞争，而30°的角度对应于最佳的热性能。估计声波极限和夹带极限的相对误差为38.7％和17.9％。干分为局部干dry（<200°C / m）和整体干dry（> 200°C / m）。结论是高填充率（100％）和小倾斜角（30°）有助于实现最佳的热性能。这项工作可以验证高温热管的运行，并为HPR的设计和应用提供参考。估计声波极限和夹带极限的相对误差为38.7％和17.9％。干分为局部干dry（<200°C / m）和整体干dry（> 200°C / m）。结论是高填充率（100％）和小倾斜角（30°）有助于实现最佳的热性能。这项工作可以验证高温热管的运行，并为HPR的设计和应用提供参考。估计声波极限和夹带极限的相对误差为38.7％和17.9％。干分为局部干dry（<200°C / m）和整体干dry（> 200°C / m）。结论是高填充率（100％）和小倾斜角（30°）有助于实现最佳的热性能。这项工作可以验证高温热管的运行，并为HPR的设计和应用提供参考。