Experimental Study on the Heat Transfer Performance of a Cesium Oscillating Heat Pipe

Abstract Due to the active chemical properties, explosive risk and high price of cesium metal, research on high-temperature oscillating heat pipe (HOHP) with cesium as a working fluid has not been reported. In view of the application of HOHPs and the need for systematic academic research, a high-temperature heat pipe with cesium as the working fluid was fabricated in this paper and the filling ratio was 50 %. The start-up and operating characteristics of the Cs-HOHP at an operating temperature of 80°C were investigated experimentally, and the effects of different inclination angles (90°, 60°, 30°, 0°) and different input powers on the heat transfer performance were analysed. The experimental results show that: (1) when the inclination angle was 90°, 60°, and 30°, the start-up temperature of Cs-HOHP was lower compared with that of HOHP with sodium, potassium, and sodium-potassium alloys as the working fluids, whereas the start-up of Cs-HOHP could not be started or had a poor start-up performance when the inclination angle was 0°. (2) At an inclination angle of 60°–90°, the heat transfer performance of Cs-HOHP was insensitive to the inclination angle, and when the inclination angle was 30°, the thermal resistance increased significantly, especially when the input power was low. (3) At an inclination angle of 90° and an input power of 3373 W, the thermal resistance was the smallest, with a value of 0.17 °C/W.