Experimental study on swing-induced thermal oscillation of horizontal sodium heat pipe

High-temperature heat pipes, renowned for their exceptional thermal conductivity and inherent safety, are extensively employed in applications such as solar receivers and small nuclear reactors. While most existing research evaluate their thermal performance under static conditions, which do not adequately represent dynamic operating environments. This study aims to examine the behavior of a horizontal sodium heat pipe under pitch and roll motions generated by a six-degree-of-freedom robotic arm, by measuring the wall temperature, vapor temperature, and vapor pressure. The results indicate that, at a heating power of 1245 W, the equivalent thermal resistance under static horizontal condition is 0.1349 K/W. Pitch motion leads to noticeable periodic oscillations in temperature and vapor pressure, with oscillation periods aligning with the motion period. Consequently, the thermal resistance varies from −9.49% to 4.30% compared to the static horizontal condition. However, no thermal oscillations were observed during roll motion, as the periodic force field did not influence the return flow of the working fluid. These findings suggest that, while high-temperature heat pipes maintain robust safety under swinging motion, the potential impact of stress oscillations on the long-term reliability of the heat pipe should still be considered. This study offers valuable insights for the design and safety assessment of high-temperature heat pipes in dynamic environments.