Studies on diffusion and natural convection of two-component gases

Takeda, Tetsuaki; Hishida, Makoto

doi:10.1016/0029-5493(92)90201-6

Cited by 22 publications

(16 citation statements)

References 9 publications

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“…According to the previous experiments (2)(3)(4) , molecular diffusion and natural convection would have occurred simultaneously in the annular passage between the inner barrel and the water-cooled jacket. The range of Rayleigh number based on the width of the annular passage is about 0 < Ra d < 3.26×10 5 and Ra d < 1.56×10 6 respectively (2,4) . Rayleigh number based on the width of the annular passage of the HTTR or the GTHTR-300C will be two orders of magnitude or bigger than that of the simulated apparatus.…”

Section: Introductionmentioning

confidence: 92%

“…In order to predict or analyze the process of air ingress during the depressurization accident of the VHTR, it is very important to develop computer programs and to validate them by experiments. Previous studies focused mostly on molecular diffusion and natural circulation of the two-component gas mixture in a reverse U-shaped tube and in a simple test model of the HTTR (2) . In order to investigate the basic features of the flow behavior of the multi-component gas mixture, consisting of helium (He), nitrogen (N 2 ), oxygen…”

Section: Introductionmentioning

confidence: 99%

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Study on the Effect of One-Dimensional Natural Circulation on the Mixing Process of Two Component Gases

Funatani

Takeda

2014

Volume 2A: Thermal Hydraulics

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This study is to investigate the effect of one-dimensional natural circulation on the mixing process of two component gases by evaluating the onset time of natural circulation through the apparatus under the stable density stratified fluid layer. The experimental apparatus consists of a reverse U-shaped vertical slot and a storage tank. The left side vertical slot consists of the heated wall and the cooled wall. The right side vertical slot consists of the two cooled walls. Temperature difference between the vertical walls was set to 50, 70, and 100 K. In this study, the combination of the two component gases is He/Ar and density ratio of each component is 1.4/10. The heavy gas was filled with the storage tank and light gas was filled with the reverse U-shaped vertical slot. Before the experiment starts, the localized natural convection was generated in the heated side vertical slot. After the experiment starts, the heavy gas will be transported to the slot by the molecular diffusion and natural convection. And then, natural circulation occurs abruptly through the reverse U-shaped passage. The mixing process of two component gases and the onset time of natural circulation in the vertical fluid layer were affected not only by the localized natural convection but also by the molecular diffusion. The wall and gas temperatures were measured by thermocouples and the velocity of natural convection was measured to evaluate the characteristics of the mixing process and the natural convection. These experimental results show that generation time of natural circulation was affected by molecular diffusion and localized natural convection. When the two components of gases have large density ratios and large Gr numbers, the mixing process of two components of gases was affected by more intensively molecular diffusion than localized natural convection when temperature difference was 50K. The mixing process of two component gas was affected by more intensively localized natural convection than molecular diffusion when temperature difference was 70 to 100K. However, two component gases were affected by more intensively molecular diffusion than localized natural convection at small density ratios and small Gr numbers.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Study on the Effect of One-Dimensional Natural Circulation on the Mixing Process of Two Component Gases

Funatani

Takeda

2014

Volume 2A: Thermal Hydraulics

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show abstract

“…The time required from the first to the second stage is about 10 s in the ingress process. Therefore, the production process of the second stage is a rapid phenomenon because the duration time of the first stage is about 165 min in the reverse U-shaped tube (Takeda and Hishida, 1992). The helium-injection method used this peculiar phenomenon is described in this paper.…”

Section: Basic Feature Of Air Ingress Process In a Reverse U-shape Tubementioning

confidence: 98%

“…The density of the gas mixture in the reactor gradually increases as air enters by the molecular diffusion and natural circulation of the gas mixture in the first stage of the accident. Finally, the second stage of the accident starts after the natural circulation of air occurs suddenly throughout the entire reactor (Takeda and Hishida, 1992).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies focused mostly on molecular diffusion and natural circulation of the two-component gas mixture in a reverse U-shaped tube and in a simple test model of the HTTR (Takeda and Hishida, 1992). In order to investigate the basic features of the flow behavior of the multicomponent gas mixture, consisting of helium (He), nitrogen (N 2 ), O 2 , CO 2 , CO, etc., experimental and numerical studies were performed on the combined phenomena of the molecular diffusion and the natural circulation of the multicomponent gas mixture with the graphite oxidation reaction in the reverse U-shaped tube .…”

Section: Introductionmentioning

confidence: 99%

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Research and development on prevention of air ingress during the primary-pipe rupture accident in the HTTR

Takeda¹

2004

Nuclear Engineering and Design

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Studies on molecular diffusion and natural convection in a multicomponent gas system

Takeda

Hishida

1996

International Journal of Heat and Mass Transfer

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Studies on diffusion and natural convection of two-component gases

Cited by 22 publications

References 9 publications

Study on the Effect of One-Dimensional Natural Circulation on the Mixing Process of Two Component Gases

Study on the Effect of One-Dimensional Natural Circulation on the Mixing Process of Two Component Gases

Research and development on prevention of air ingress during the primary-pipe rupture accident in the HTTR

Studies on molecular diffusion and natural convection in a multicomponent gas system

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