Physical insight in the burnout region of water-subcooled flow boiling

Revue Générale de Thermique Pub Date : 1998-06-01 DOI:10.1016/S0035-3159(98)80062-7

Gian Piero Celata, Maurizio Cumo, Andrea Mariani, Giuseppe Zummo

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引用次数: 15

Abstract

The present paper reports the results of a visualization study of the burnout in subcooled flow boiling of water, with square cross-section annular geometry (formed by a central heater rod contained in a duct characterised by a square cross-section). In order to obtain clear pictures of the flow phenomena, the coolant velocity is in the range 3–9 m·s⁻¹ and the resulting heat flux is in the range 7–13 MW·m⁻². From video images (single frames were taken with a light exposure of 1 μs) the following general behaviour of vapour bubbles was observed: when the rate of bubble generation is increasing, with bubbles growing in the superheated layer close to the heating wall, their coalescence produces a sort of elongated bubble called a vapour blanket. One of the main features of the vapour blanket is that it is rooted to the nucleation site on the heated surface. Bubble dimensions, as well as those of the hot spots, are given as a function of thermal-hydraulic tested conditions.

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水过冷流动沸腾燃尽区的物理认识

本文报道了一种方形截面环形几何结构(由包含在方形截面的管道中的中央加热棒形成)的过冷流沸水燃尽可视化研究的结果。为了获得流动现象的清晰图像，冷却剂速度范围为3-9 m·s−1，所得热流密度范围为7-13 MW·m−2。从视频图像(单帧以1 μs光照拍摄)中观察到蒸汽气泡的一般行为:当气泡生成速率增加时，气泡在靠近加热壁的过热层中生长，它们的结合产生一种细长的气泡，称为蒸汽毯。蒸汽包层的一个主要特点是它扎根于受热表面的成核部位。气泡的尺寸以及热点的尺寸是作为热-水力测试条件的函数给出的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Revue Générale de Thermique

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