Influence of Inclination Angle on the Start-up Performance of a Sodium-Potassium Alloy Heat Pipe |
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Authors: | Qing Guo Xiao Ke Yan Fang Ye Chong Fang Ma |
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Affiliation: | 1. MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, and Beijing Key Laboratory of Heat Transfer and Energy Conversion, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing, China;2. National Institute of Metrology, Beijing, China |
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Abstract: | ABSTRACTAlkali metal heat pipes play significant role in various high-temperature engineering applications because of their excellent heat transfer capacity. Inclination angle is one of major factors which significantly affect start-up and heat transfer characteristics especially for thermosiphons. A sodium-potassium alloy (Na-K) gravity-driven heat pipe (GHP), in which the content of potassium in Na-K is wt. 55%, was fabricated to study the effect of inclination angle on start-up and heat transfer capacities of high-temperature GHPs. The Na-K GHPs was fixed by the adjusting bracket in 9 inclination angles (0°, 10°, 20°, 30°, 40°, 50°, 60°, 70° and 80°). Outside wall temperature was measured by eleven thermocouples which calibrated by the China Institute of Metrology prior to using them in the experiments. Results show that inclination angle has a significant impact on start-up and heat transfer performances of the Na-K GHP because of the impact of gravity on the two-phase flow inside the heat pipe and effective heating area in the evaporator. Start-up and heat transfer characteristics are dramatically improved and temperature difference significantly decreases as the inclination angle increases from 0° to 50°, but slightly decreases when the inclination angle exceeds 60°. |
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