Development of Closed Two-Phase Thermosyphon for Decay Heat Removal System

衰变热排出系统闭式两相热虹吸管的研制

• 批准号: 14580540
• 负责人: KAMINAGA Fumito
• 金额: $ 2.3万
• 依托单位: Ibaraki University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14580540/
• 关键词: Two-phase thermosyphon; Boiling heat transfer; Maximum heat flux; Condesation heat transfer; Decay heat; Passive system; 静的機器; 沸騰熱伝導; パッシブ

A special type thermosyphon, a looped parallel thermosyphon referred to LPT, has been developed for obtaining better heat transfer performance than a conventional single tube thermosyphon referred to STT. The LPT consists of two STTs joined each other at top and bottom by two U-tubes. The purpose of this study is to obtain fundamental knowledge regarding to heat transfer characteristics of the LPT in order to apply it to a passive heat decay removal system of a nuclear reactor. Effects of fill charge ratio and system pressure on the heat transfer and effect of flow fluctuation in the condenser part on condensation heat transfer in the presence of non-condensable gas are mainly examined. Experiments are conducted with water and ethanol working fluids in wide ranges of system pressures of 23 to 144 kPa for ethanol and 12 to 57 kPa for water, charge ratio of 0.3 to 0.9 and coolant temperatures of 25 to 50 ℃. Experiments using a STT are also conducted to compare with the heat transfer characteristics of the LPT on the same conditions.Major findings of the experiments are as follows : In the evaporator part, the wall temperature profile is more uniform than that in the STT and the heat transfer coefficient is similar between LPT and STT. The maximum heat flux obtained in the LPT excluding a noncondensable gas is three to four times larger than that in STT for both working fluids. But including the gas it falls down to a lower value than that in STT. The reason of the decrease is not clear and has been remained to be investigated. The effect of fluid fluctuation in the bottom U tube on the condensation heat transfer is minor and the effect of the noncondensable gas on the condensation heat transfer can not be minimized by the fluid flow fluctuation which was expected before the experiments.

已经开发出一种特殊类型的热态，即提及LPT的循环平行热轴，它是为了获得更好的传热性能，而不是传统的单管热孔。 LPT由两个stt组成，在顶部和底部通过两个U管组成。这项研究的目的是获得有关LPT传热特征的基本知识，以便将其应用于核反应堆的被动热衰减去除系统。主要检查了填充电荷比和系统压力对冷凝器部分中流动波动的热传递和在存在不可传递气体的情况下的热传热的影响。实验是用水和乙醇工作流体进行的，乙醇的系统压力为23至144 kPa，水为12至57 kPa，充电比为0.3至0.9，冷却液温度为25至50℃。还进行了使用STT的实验，以与LPT在相同条件下的传热特性进行比较。实验的发现如下：在蒸发器部分中，壁温度曲线比STT中的壁温度更为均匀，而LPT和STT之间的传热系数相似。在LPT中获得的最大热通量（不可固定的气体）是两个工作烟道的三到四倍。但包括气体降低到比STT中的气体低。下降的原因尚不清楚，并且仍有待调查。底部U管中的流体波动对冷凝热传热的影响很小，不可固定气体对冷凝热传热的影响无法通过在实验之前预期的流体流动波动来最小化。