Experimental study of heat transfer characteristics of bent high-temperature heat pipe

The heat pipe, as a highly efficient heat transfer element, is well adapted to industrial applications with high heat flux. For compact system designs and compatibility with energy converters, bent high-temperature heat pipes are essential. However, the current research on the bending effect of heat pipes mainly focuses on the medium and low-temperature range, and there is a lack of systematic experiments on the heat transfer characteristics of bent high-temperature heat pipes. In this study, high-temperature sodium heat pipes were used as experimental objects, and the bend radius, wick structure type, bend position and bend number were set as variables to examine the changes in heat transfer characteristics of high-temperature heat pipes before and after bending by utilizing the axial temperature distribution, thermal resistance and heat transfer limit. High-temperature heat pipes exhibit performance degradation after bending, with increased thermal resistance and reduced heat transfer limits, significantly influenced by bend radius and wick structure. A bend radius of 250 mm raises temperatures by 40 °C and reduces the heat transfer limit by 10.48 %. Screen wick types show better resistance to bending with less than 10 % performance loss, while artery types deteriorate by 35.21 %. Bend position also affects performance; a lower bend position has better results. The performance of the heat pipe is not significantly degraded by the double bends and the bends near the evaporation section are the main cause of the degradation.