Numerical Simulation of Displacement Process of Liquid Scintillator and Ultrapure Water in a Large Diameter Spherical Tank
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摘要: 中微子实验装置一方面需要屏蔽大量的宇宙射线和来自岩石、空气、灰尘的天然放射性;另一方面需要尽可能降低实验设施自身的放射性本底。本文利用计算流体动力学(CFD)软件模拟研究了中心探测器(大直径球罐)内液体闪烁体(简称液闪)和超纯水的置换过程,分析水中的放射性杂质进入液闪的情况,研究自然对流对置换过程中液闪本底的影响。通过模拟无自然对流和有自然对流2种工况,得到2种工况下液闪和水的相态与流态分布以及相含量随时间的变化情况,提取出相界面处竖直向上速度,并计算得出截面向上总流量,以判断自然对流对置换过程的影响。结果表明:在有自然对流工况下液闪向上的平均体积流量是小于无自然对流状态的,可知自然对流可以抑制水中放射性杂质进入液闪。
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关键词:
- 大直径球罐 /
- 计算流体动力学(CFD) /
- 置换 /
- 自然对流
Abstract: On the one hand, the Neutrino experimental facility needs to shield a lot of cosmic rays and natural radioactivity from rocks, air and dust. On the other hand, it is necessary to reduce the radioactive background of the experimental facility as much as possible. In this paper, the displacement process of liquid scinulator (liquid flash) and ultrapure water in the central detector (large-diameter spherical tank) is studied by CFD simulation. The situation of radioactive impurities in the water entering the liquid scinulator is analyzed, and the effect of natural convection on the liquid flash background during the displacement is studied. By simulating the two conditions of "no natural convection" and "with natural convection", the phase and flow distribution under the two different conditions was obtained, and the changes in the phase content with time are also obtained. The vertical upward velocity at the phase interface was extracted, and the total upward flow of the section was calculated to judge the influence of natural convection on the displacement process. The results show that the upward average volume flow of the liquid scintillator in the natural convection is less than that under the condition of no natural convection, which shows that natural convection can inhibit radioactive impurities from entering the liquid scintillator.-
Key words:
- Large diameter spherical tank /
- CFD /
- Displacement /
- Natural convection
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表 1 球形中心探测器尺寸
Table 1. Size of Spherical Center Detector
名称 进液管 中心探测器 出液管 内径/m 0.8 35.4 1.0 容积/m3 1.01 23228 48.77 表 2 液闪属性参数
Table 2. Properties of Liquid Scintillator
密度/
(kg·m−3)导热系数/
[W·(m·K)−1]比热容/
[J·(kg·K)−1]黏度/
[(kg·m)·s−1]体积膨胀
系数/K−1856 0.1426 2304 4.012×10−3 8.9×10−4 表 3 不同工况设置
Table 3. Settings of Different Operating Conditions
工况设置 工况一(无自然对流) 工况二(有自然对流) 相的数量 两相 两相 初始液闪体积分数 0 0 液闪密度/(kg·m−3) 不变 变化 入口温度/℃ 24 24 球壁面温度/℃ 24 20~22.74 计算工况 瞬态 瞬态 -
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