Thermal-hydraulic Phenomena Relevant to Global Dryout in a Hemispherical Narrow Gap

Jeong, Jin Hee; Park, R. J.; Kim, S. B.

doi:10.1007/s002310050266

Cited by 8 publications

(3 citation statements)

References 7 publications

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“…The pictures of the hot vessel by the video camera did not show any signature of fast cooling of the wall in the lower part. It should be remarked here that recent results (Jeong et al, 1998) show that the critical heat flux (CHF) in a narrow spherical curved gap is ∼ =50-100 kW/m 2 , which is of the same order as the radiation heat loss from the bottom head wall external sur- face. Details of the cooling rate will be discussed in the next few sections.…”

Section: Experimental Results For Bottom Head Wall Temperaturesmentioning

confidence: 95%

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Experiments on in-vessel melt coolability in the EC-FOREVER Program

Sehgal

Giri

Chikkanagoudar

et al. 2006

Nuclear Engineering and Design

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Section: Experimental Results For Bottom Head Wall Temperaturesmentioning

confidence: 95%

“…Several experiments have also been constructed, with a gap of specific dimensions (1-3 mm) between a heated hemispherical vessel and an outer unheated vessel. The critical heat flux, with water flooding of the gap, was measured (Jeong et al, 1998;Asmolov et al, 1999;Köhler et al, 1998). The values of CHF obtained are not very high.…”

Section: Introductionmentioning

confidence: 99%

Experiments on in-vessel melt coolability in the EC-FOREVER Program

Sehgal

Giri

Chikkanagoudar

et al. 2006

Nuclear Engineering and Design

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“…[11] correlated them in terms of Wallis parameters using W as a CL. ** original data were presented in terms of Wallis parameters and correlated by Jeong et al [24] *** Original data were presented in terms of Wallis parameters and correlated by San Fabian et al [25] j G The test rig was designed such that the water and air flows will be evenly distributed. A schematic diagram of the test facility is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Counter-current flow limitation velocity measured in annular narrow gaps formed between large diameter concentric pipes

Jeong

2008

Korean J. Chem. Eng.

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A two-phase flow configuration in which the gas phase flows upwards while the liquid phase flows downwards is referred to as a counter-current flow pattern. This flow configuration cannot be preserved if any flow rate exceeds a criterion known as the counter-current flow limitation (CCFL) or flooding. Since the CCFL is important to chemical engineers, it has long been studied via experimental and analytical approaches. Most of the previous CCFL experiments in annular channels have been carried out with a small diameter annulus and large gap-to-diameter ratio annulus. The present experiment examines the CCFL in narrow annular channels having gap sizes of 1, 2, 3, and 5 mm. The outer diameter of the annular passage is 500 mm. At a gap size of 1 mm, it was visually observed that a CCFL locally occurred in some region of the periphery while the other region remained in a counter-current flow configuration. The region under partial CCFL condition expanded with an increase in the air flow rate, finally reaching a global CCFL. The air flow rate for the global CCFL was roughly 15% larger than that for initiation of a partial CCFL. This difference in air flow rate between the initiation of a partial CCFL and the global CCFL was reduced as the gap size increased. When the gap size was 5 mm, the partial CCFL was not observed, but onset of flooding led to a global CCFL. Because of the existence of a transient period, the CCFL was experimentally defined as the situation where net water accumulation is sustained. The measured CCFL data are presented in the form of a Wallis' type correlation. Two length scales, hydraulic diameter and average circumference, were examined as the characteristic length scale. The average circumference appeared to better fit the experimental data, including results reported elsewhere. A new correlation using the average circumference as the characteristic length scale is suggested based on the experimental measurements of the present work and previous reports.

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Critical heat removal rate through a hemispherical narrow gap

Park

Kang

et al. 2003

Heat and Mass Transfer

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Thermal-hydraulic Phenomena Relevant to Global Dryout in a Hemispherical Narrow Gap

Cited by 8 publications

References 7 publications

Experiments on in-vessel melt coolability in the EC-FOREVER Program

Experiments on in-vessel melt coolability in the EC-FOREVER Program

Counter-current flow limitation velocity measured in annular narrow gaps formed between large diameter concentric pipes

Critical heat removal rate through a hemispherical narrow gap

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