振荡条件下熔融池传热特性研究

Research on Heat Transfer Characteristics of Corium Pool Under Oscillating Conditions

为获得振荡条件下熔融池的传热特性,本研究以海洋小型反应堆(简称海洋小堆)双层熔融池为对象开展实验研究。实验采用氟化液FC-40和水分别模拟熔融池的氧化层和金属层,获得了不同振荡条件下熔融池的温度场以及传热量的瞬态变化情况。实验结果显示,振荡条件在运动初始阶段对熔融池的影响最为剧烈,随着振荡运动的持续,熔融池会达到热平衡准稳态。一般情况下,振荡条件下熔融池的温度分层减弱,整体温度较静止条件下的温度低,且向冷却壁面的传热量增大。在相同的高强度振荡条件下,纵向振荡的影响比横向振荡更为剧烈,而在低强度振荡条件下,纵向振荡的影响可以忽略。此外,本研究提出了一个新的无量纲参数Lo来表征振荡影响强度,该参数表示在振荡条件下,特征振荡附加力与流体的特征剪切力之比,可用于量化在相同振荡方向条件下不同振荡强度的影响。本研究成果可为海洋小堆的熔融物堆内滞留(IVR)分析和安全系统的设计提供有价值的参考。

In order to obtain the heat transfer characteristics of corium pool under oscillating conditions,an experimental study was carried out on the two-layer corium pool of small marine reactors.Fluorinert liquid FC-40 and water were used respectively to simulate the oxide layer and metal layer of corium pool in the experiment,and the transient variations of temperature field and heat transfer capacity under different oscillating conditions were obtained.The experimental results show that the oscillating conditions exert the most intense influences in the early stage of movements,and as the oscillating motion continues,the corium pool will reach a quasi-steady state of thermal equilibrium.In general,the temperature stratification of corium pool is weakened under the condition of oscillation,and the overall temperature is lower than that under the static condition,together with the increased heat transfer capacity to the cooling wall.Under the same high-intensity oscillating conditions,the effect of oscillations in vertical direction is more intense than that of oscillations in lateral direction.However,under the condition of low-intensity oscillation,the effect of oscillations in vertical direction can be ignored.Additionally,a new dimensionless parameter Lo was proposed to characterize the oscillatory influence strength,which represents the ratio of the characteristic oscillatory force to the characteristic shear force of fluid under oscillating conditions.It can be used to quantify the influence of different oscillation intensities under the same oscillation direction.This research is supposed to offer valuable reference to the in-vessel retention(IVR)analysis and safety system design for small marine reactors.