Numerical investigation of intermittent dryout in diabatic vapor-water annular flow in an upward vertical tube

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering Pub Date : 2025-05-12 DOI:10.1016/j.applthermaleng.2025.126806

Xin Zhang , Jianxin Shi , Xu Chen , Baozhi Sun , Wanze Wu , Qingpeng Zeng

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Abstract

Dryout is a key limitation to heat transfer efficiency in high heat flux systems, and its triggering mechanism must be elucidated through the analysis of liquid film interfacial behavior in diabatic annular flow. This study examines vertical upward vapor–liquid diabatic annular flows of water at 7 MPa, with a mass flux of 750 kg/(m²·s), and an inlet vapor quality of 0.5, under three distinct heat flux conditions representative of operating conditions in once-through steam generators (OTSGs). The spatial–temporal distributions of liquid film thickness are examined, along with the axial variations in base film thickness and wave amplitude. The relationship between liquid film thickness distribution and wall temperature was explored, with particular attention to the correspondence between the timing of temperature rise and the liquid film thickness reaching a local minimum. The results indicate that the mass source is higher in the base film region, and the rupture of the base film leads to direct vapor-wall contact, causing localized vapor superheating. Higher heat flux results in an increased intermittent dryout fraction.

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竖直管内非绝热蒸汽-水环流间歇干化的数值研究

干干是影响高热流密度系统换热效率的关键因素，必须通过分析非绝热环空流动中的液膜界面行为来阐明其触发机制。本研究考察了7 MPa、质量通量为750 kg/（m2·s）、进口蒸汽质量为0.5的水在三种不同热流密度条件下垂直向上的汽液非绝热环流，这些热流密度条件代表了一次性蒸汽发生器（otsg）的运行条件。研究了液膜厚度的时空分布，以及基膜厚度和波幅的轴向变化。探讨了液膜厚度分布与壁面温度的关系，特别注意了温度上升时间与液膜厚度达到局部最小值的对应关系。结果表明：基膜区质量源较高，基膜破裂导致气壁直接接触，造成局部蒸汽过热；较高的热通量导致间歇干化率增加。

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来源期刊

Applied Thermal Engineering 工程技术-工程：机械

CiteScore

11.30

自引率

15.60%

发文量

1474

审稿时长

57 days

期刊介绍： Applied Thermal Engineering disseminates novel research related to the design, development and demonstration of components, devices, equipment, technologies and systems involving thermal processes for the production, storage, utilization and conservation of energy, with a focus on engineering application. The journal publishes high-quality and high-impact Original Research Articles, Review Articles, Short Communications and Letters to the Editor on cutting-edge innovations in research, and recent advances or issues of interest to the thermal engineering community.