Experimental investigations on start-up and thermal performance of sodium heat pipe under swing conditions

Abstract High-temperature heat pipes (HTHPs) have a potential of being used for passive heat dissipation of marine nuclear reactors in emergency. In order to understand the influence of wave action on the performance of HTHPs, a sodium heat pipe is fabricated and experimentally tested in this work. The effects of low-frequency swing on start-up and thermal performance of this heat pipe are examined and compared with the static state tests. The results show that swinging motion has a negligible influence on the whole start-up performance of the heat pipe, however, it would lead to the small-amplitude periodic temperature fluctuations especially at the evaporator. Temperature fluctuation frequency is nearly corresponding to the swing, and the temperature fluctuation amplitude is increased with the swing amplitude. The steady-state thermal performance is slightly decreased with increasing swing speed and decreasing swing amplitude in terms of thermal resistance under test conditions, but the influence seems negligible as well.