Mechanism research of two-phase flow regimes during bottom reflooding in narrow rectangular channel. (February 2021)

• Record Type: Journal Article
• Authors: Xu, Wei; Deng, Yonghao; Liu, Xiaojing; Cheng, Xu; Wu, Dan
• Is Part Of: Annals of nuclear energy. Volume 151(2021)
• Publication Date: 2021-02
• Subjects: Bottom Reflooding -- Narrow Rectangular Channel -- Two-phase Flow Regimes -- Rewetting Front; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2020.107977
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Bottom reflooding visualization experiments are conducted within narrow rectangular channel. Novel method is put forward to determine the quench front and rewetting front precisely. The thickness effects to the bottom reflooding thermal–hydraulic behaviors are analyzed. Two-phase flow regimes during bottom reflooding are discussed qualitatively and quantitatively. Abstract: Visualization experiments and mechanism analysis were performed to fully investigate the thermal hydraulic behaviors during bottom reflooding within narrow rectangular channel. Qualitative and quantitative analysis of the two-phase flow regimes were conducted by means of high-speed camera. Conclusions can be obtained that five flow regimes were observed, including dispersed flow, inverse annular flow, rewetting front, coalesced bubble flow and isolated bubble flow; when the narrow rectangular channel thickness decreases from 5.0 to 2.0 mm, the rewetting velocity and corresponding critical heat flux decrease severely due to the space limitation, whereas the heat transfer capacity increases in the low superheat region; the locations of rewetting front can be determined both by image processing and 'temperature variation speed curve' method, and the mutual authentication results reveal that the visible three-phase contact line and highest point of the temperature variation curve can be regarded as the rewetting front during bottom reflooding.