Critical Heat Flux of Narrow Vertical Annuli With Closed Bottoms
Critical Heat Flux of Narrow Vertical Annuli With Closed Bottoms
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DOI：
10.1115/1.3245542
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发表时间：
1983-02
影响因子：
--
通讯作者：
Yung Chang;S. Yao
中科院分区：
文献类型：
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作者：
Yung Chang;S. Yao
各种传热设备中都可能存在窄环。当加热的狭窄垂直环形空间在底部封闭并充满液体时，可能会发生沸腾并且可能会超过临界热通量。一个实际的例子是立式蒸汽发生器中加热管和管板之间的狭窄环形空间。环隙的间隙通常为0.25mm量级；环形体的底端通过焊接封闭。在底部管板附近的加热管上观察到严重的腐蚀。据信，限制在具有封闭底部的狭窄环中导致低临界热通量和在过渡沸腾状态下的操作。在这些位置，腐蚀的发生速度可能比蒸汽发生器其他地方高几个数量级[1]。研究垂直闭底窄环空间中临界热通量的基本性质对于理解热水力相关腐蚀具有重要意义。
Narrow annuli may exist in various heat transfer equipment. When a heated narrow vertical annulus is closed at the bottom and filled with liquid, boiling may occur and critical heat flux may be exceeded. A practical example is the narrow annuli between the heated tubes and the tube sheet in vertical steam generators. The gaps of the annuli are usually in the order of 0.25 mm; the bottom ends of the annuli are closed by welding.Serious corrosion has been observed on the heated tubes near the bottom tube sheet. It is believed that confinement in the narrow annuli with closed bottoms results in a low critical heat flux and operation in the transition boiling regime. At these locations corrosion may proceed at rates [1] several orders of magnitude higher than elsewhere in the steam generator. The study of the fundamental nature of critical heat flux in the vertical closed-bottom narrow annulus will be important to the understanding of the thermal-hydraulic related corrosion.