Coolability of particulate beds in severe accidents: Status and remaining uncertainties

Bürger, M.; Buck, M.; Pohlner, Georg; Rahman, Saidur; Kulenovic, Rudi; Fichot, F.; Ma, Weimin; Miettinen, Jorma K.; Lindholm, Ilona; Atkhen, Kresna

doi:10.1016/j.pnucene.2009.09.015

Cited by 34 publications

(4 citation statements)

References 17 publications

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“…Majority of investigations on multiphase flows in systems involving heat-generating porous media primarily deal with determination of the critical heat flux (CHF) and/or the dryout heat flux (DHF) in different situations [20][21][22][23][24][25][26][27][28][29]. WHile CHF quantifies the maximum thermal energy that can be removed from a system, DHF quantifies the minimum thermal energy level at which a system becomes uncoolable.…”

Section: Introductionmentioning

confidence: 99%

Impact of liquid coolant subcooling on boiling heat transfer and dryout in heat-generating porous media

Chakravarty¹,

Ghosh²,

Sen³

et al. 2021

Preprint

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The present article discusses the impact of liquid coolant subcooling on multiphase fluid flow and boiling heat transfer in porous media with internal heat generation. Although extremely relevant and important, only limited studies are available in the open literature on the effects of coolant subcooling in heat-generating porous media and hence, this requires a detailed analysis. The analysis is carried out using a developed computational model of multiphase fluid flow through clear fluid and porous media considering the relevant heat transfer and mass transfer phenomena. Results suggest that the qualitative nature of boiling heat transfer from the heat-generating porous body, with subcooled coolants, remain similar to that observed with a saturated coolant. Quantitative differences are, however, observed as a result of solid-liquid convective heat transfer, and competing mechanisms of boiling and condensation heat transfer, when subcooled liquid coolant is present. It is observed that a substantially larger heating power density is requiredas coolant subcooling is increased -for achieving the same temperature rise in the porous body. Dryout power density at different coolant subcooling is also observed to follow a similar trend. The thermal energy removal limit is, hence, observed to be substantially enhanced in presence of subcooled coolants. Further, the dryout region within the porous body is observed to gradually shift towards its interior as the coolant subcooling is increased.

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Section: Introductionmentioning

confidence: 99%

Impact of liquid coolant subcooling on boiling heat transfer and dryout in heat-generating porous media

Chakravarty¹,

Ghosh²,

Sen³

et al. 2021

Preprint

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“…In the context of nuclear safety, study of the dryout of an initially flooded bed of particles is a key topic [1,2]. Such a situation may occur following a major accident provoking the reactor core fragmentation (such as a loss of coolant accident), leading to the formation of a debris bed in the nuclear reactor vessel.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the dryout of a 2D heat-generating model porous medium

Gourbil

Fichot

Prat

et al. 2019

Experimental Thermal and Fluid Science

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Dryout experiments are performed in a quasi two-dimensional heat-generating model porous medium, with bottom flooding. The test section is composed of an array of heating cylinders placed between two ceramic plates. It is held vertically and a liquid (HFE-7000) is injected from bottom at a controlled flow rate, pressure and temperature. Dryout incipient power is investigated by applying an increasing thermal power to a bundle of heating cylinders until a dry zone is detected. The liquid inlet mass fluxes range from 1.0 kg m s 2 1 to 10.5 kg m s 2 1 and the heat fluxes are between 195 kW m 2 and 1086 kW m 2. Two kinds of dryout phenomenology are observed. First, at low liquid injection rate (below 4.2 kg m s 2 1 inlet mass flux), reaching the dryout power results into a liquid front receding from the top of the test section to the upper limit of the heated zone, while downstream the heated zone, the porous medium is vapour-saturated. Second, at higher flow rate (over 5.2 kg m s 2 1 inlet mass flux), the boiling crisis happens at the surface of a single heating element, resulting in a local film boiling, whereas a two-phase flow still go through the whole test section. In both cases, high-speed visualizations allow characterizing 8 boiling/flow regimes, depending on the inlet mass flux, the power released by the heated zone, and the location inside the porous medium. In particular, when reaching the dryout incipient power, the existence of a pulsed flow regime is highlighted. Such a characterization of boiling/ flow regimes might be helpful in improving dryout models.

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“…The models are related to the knowledge and treatment of two-phase flow and heat transfer in porous media. Summaries and reviews of the previous studies can be found in the works of Bürger et al (2010), Nemec and Levec (2005), Schmidt (2004), Lindholm (2002) and Dullien (1975).…”

Section: Introductionmentioning

confidence: 99%

Pressure drops of single/two-phase flows through porous beds with multi-sizes spheres and sands particles

Zou

Lou

et al. 2015

Annals of Nuclear Energy

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Coolability of particulate beds in severe accidents: Status and remaining uncertainties

Cited by 34 publications

References 17 publications

Impact of liquid coolant subcooling on boiling heat transfer and dryout in heat-generating porous media

Impact of liquid coolant subcooling on boiling heat transfer and dryout in heat-generating porous media

Experimental study of the dryout of a 2D heat-generating model porous medium

Pressure drops of single/two-phase flows through porous beds with multi-sizes spheres and sands particles

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