Experimental study on the rewetting velocity on dry out surface due to stepwise boundary condition changes

IF 1.9 3区工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Nuclear Engineering and Design Pub Date : 2025-03-29 DOI:10.1016/j.nucengdes.2025.114020

A. Satou, Y. Wada, Y. Sibamoto

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引用次数: 0

Abstract

Post-boiling transition (post-BT) heat transfer is essential for analyzing the duration of surface dryout and peak cladding temperature during abnormal transients and accidents in light water reactors. The rewetting phenomenon, in which the liquid film front propagates to the dryout surface and becomes wet again due to a decrease in heat flux or an increase in flow rate, is very important for evaluating the dryout duration. Although rewetting velocity models have been proposed mainly for reflooding processes, mechanical rewetting velocity models applicable to much higher flow and heat flux conditions than reflooding processes have been developed in recent years. However, due to the lack of an experimental database on rewetting velocities under such a wide range of thermal–hydraulic conditions, sufficient data for model development and validation do not exist. Therefore, a database on rewetting velocities caused by stepwise boundary condition changes under a wide range and multiple combination of thermal–hydraulic conditions was obtained using a single-tube experimental apparatus. Based on this database and the characteristics of rewetting velocities obtained, an empirical correlation for rewetting velocity was proposed. This correlation predicts the rewetting velocity accurately by taking the change in the mass flux of the liquid or gas phase with stepwise transients as a parameter. This suggested that the change in the mass flux of the gas or liquid phase near the liquid film front has a strong influence on the rewetting under extremely high mass flux conditions compared to the reflooding process.

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边界条件逐级变化下干湿表面复湿速度的实验研究

沸点后转变传热是分析轻水堆异常瞬态和事故中表面干化持续时间和包层峰值温度的关键。再润湿现象是指由于热通量的减小或流量的增大，液膜锋向干区表面扩散并再次变湿的现象，它对评价干区持续时间具有重要意义。虽然目前提出的再润湿速度模型主要适用于再注水过程，但近年来开发了适用于比再注水过程高得多的流量和热通量条件的机械再润湿速度模型。然而，由于缺乏在如此广泛的热-水力条件下的再润湿速度的实验数据库，因此不存在足够的数据来开发和验证模型。因此，利用单管实验装置获得了大范围、多工况组合下边界条件逐级变化引起的重润湿速度数据库。在此基础上，结合获得的再润湿速度特征，提出了再润湿速度的经验关系式。该关系式以液相或气相的质量通量变化为参数，准确地预测了再润湿速度。这表明，在极高质量通量条件下，液膜前缘附近气相或液相质量通量的变化对再润湿过程的影响强于再润湿过程。

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来源期刊

Nuclear Engineering and Design 工程技术-核科学技术

CiteScore

3.40

自引率

11.80%

发文量

377

审稿时长

5 months

期刊介绍： Nuclear Engineering and Design covers the wide range of disciplines involved in the engineering, design, safety and construction of nuclear fission reactors. The Editors welcome papers both on applied and innovative aspects and developments in nuclear science and technology. Fundamentals of Reactor Design include: • Thermal-Hydraulics and Core Physics • Safety Analysis, Risk Assessment (PSA) • Structural and Mechanical Engineering • Materials Science • Fuel Behavior and Design • Structural Plant Design • Engineering of Reactor Components • Experiments Aspects beyond fundamentals of Reactor Design covered: • Accident Mitigation Measures • Reactor Control Systems • Licensing Issues • Safeguard Engineering • Economy of Plants • Reprocessing / Waste Disposal • Applications of Nuclear Energy • Maintenance • Decommissioning Papers on new reactor ideas and developments (Generation IV reactors) such as inherently safe modular HTRs, High Performance LWRs/HWRs and LMFBs/GFR will be considered; Actinide Burners, Accelerator Driven Systems, Energy Amplifiers and other special designs of power and research reactors and their applications are also encouraged.