Prediction of Void Fraction in Subcooled and Low Quality Boiling Regions

Sekoguchi, Kotohiko; Tanaka, Osamu; Esaki, Shuji; Imasaka, Takuo

doi:10.1299/jsme1958.23.1475

Cited by 19 publications

(3 citation statements)

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“…Where, ∆ is wall super heat at onset of vapour generation. Sekoguchi et al (1980) developed an empirical correlation for the wall super heat at commencement of fully developed boiling region as given by Equation 19.…”

Section: Partial Nucleate Boilingmentioning

confidence: 99%

Wall Heat Flux Partitioning Analysis for Subcooled Flow Boiling of Water-Ethanol Mixture in Conventional Channel

Suhas¹,

Sathyabhama²,

Veerabhadrappa³

et al. 2019

Frontiers in Heat and Mass Transfer

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In the present study, heat transfer coefficient of water-ethanol mixture in the subcooled boiling region is determined in a rectangular conventional channel (Channel size ≥3 mm). When the heat flux and mass flux increase it is observed that heat transfer coefficient increases. But the effect of heat flux is significant when compared with that of mass flux in the subcooled boiling region. It is found that maximum and minimum heat transfer coefficient are observed for mixture with 25% Ethanol volume fraction and 75% Ethanol volume fraction respectively. Wall heat flux partitioning analyses is carried out for mixture with different ethanol volume to determine the contribution of heat flux towards convection, agitation and evaporation. It is also found that heat flux due to convection decreases with increase in heat flux at partial and fully developed nucleate boiling heat regions for all volume fractions. The heat flux determined from the partitioning analysis are lower than the experimentally determined heat flux values at the partial nucleate boiling region and are higher at the fully developed boiling region.

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Section: Partial Nucleate Boilingmentioning

confidence: 99%

Wall Heat Flux Partitioning Analysis for Subcooled Flow Boiling of Water-Ethanol Mixture in Conventional Channel

Suhas¹,

Sathyabhama²,

Veerabhadrappa³

et al. 2019

Frontiers in Heat and Mass Transfer

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“…This correlation has a high reliability for the node-average void distribution based on a wealth of experience. 25) Unfortunately, no subchannel analysis code capable of accurately treating the subchannel-wise void fraction in the subcooled boiling region is available for verification. Therefore, Sekoguchi's correlation is not applied in this study.…”

Section: Application Of Drift-flux Model and Consideration Of Subcoolmentioning

confidence: 99%

Application of Quick Subchannel Analysis Method for Three-Dimensional Pin-by-Pin BWR Core Calculations

Tada

Fujita

Endo

et al. 2011

Journal of Nuclear Science and Technology

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Three-dimensional pin-by-pin core analysis is considered to be a candidate for the next-generation BWR core calculation method. In our previous study, the applicability of the transport and burnup calculations for a three-dimensional pin-by-pin BWR core analysis was investigated. However, the thermal-hydraulics calculation has not yet been studied in this framework. In the conventional core analysis code, the bundlewise thermal-hydraulics calculation is adopted. In the actual core analysis, the power distribution inside a fuel assembly is tilted at the region adjacent to a control blade or the core peripheral region. In these regions, the consideration of the subchannel-wise void distribution has an impact on the fission rate distribution. Therefore, an evaluation of the detailed void distribution inside an assembly, i.e., the incorporation of the subchannel wise void distribution, is desirable for the pin-by-pin BWR core analysis. Although several subchannel analysis codes have been developed, these subchannel analysis codes generally require a large computational effort to estimate the subchannel-wise void distribution in a whole BWR core. Therefore, to analyze a whole BWR core within a reasonable computation time, it was necessary to apply a fast subchannel analysis code. In this paper, a quick subchannel analysis code dedicated to pin-by-pin BWR core analysis is newly developed, and the void distribution of the present subchannel analysis code is compared with the prevailing subchannel analysis code NASCA using three-dimensional single-assembly geometries. Since the present subchannel analysis code is used for a coupled neutronics/thermal-hydraulics analysis, the results of the coupling calculation are also compared with those of NASCA. The calculation result indicates that the void distribution difference between NASCA and the present subchannel analysis code is slightly less than 10%. This result indicates that the prediction accuracy of the present subchannel analysis code will be reasonably appropriate for a pin-by-pin BWR core analysis. Furthermore, the results show that the calculation time of the present subchannel analysis code is only 10 min for a hypothetical three-dimensional ABWR quarter-core geometry using a single CPU. This calculation time is sufficient for a pin-by-pin BWR core analysis.

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“…The void profile is affected sensitively by an experimental apparatus (a bubble generating device( 2 ) and an entrance section( 4 ), for example). The mechanism of saddle shape void profile, that maintains most bubbles at the certain distance close to the wall surface can be explained by the following two theories :…”

Section: Introductionmentioning

confidence: 99%

Effects of Wall Roughness and Entry Length on Void Profile in Vertical Bubbly Flow

Takamasa¹

1988

Journal of Nuclear Science and Technology

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An experimental study of upward air-water bubbly two-phase flow in an entry region was performed with various rough wall test tubes. The objective of the work is to clarify the effects of wall roughness and entry length on void profile. The fluid flows in the vertical circular test tube of 25 mm I. D. under nearly atmospheric pressure, at room temperature. The void profile changes from a pattern similar in appearance to the saddle shape which has local void peaks near the wall, into the power law shape whose curve is approximated by a power law formula, with increasing wall roughness and/or entry length. That is, wall roughness and entry length have a similar effect upon void profile. There are two patterns in the power law shape, a pattern with sharp center peak and a pattern with obtuse center peak. As wall roughness and/or entry length increase, the void profile changes from the former pattern to the latter pattern. At enough long entry length (L/D ~ 150), every void profile has almost the same power law shape independent of wall roughness. Some void profiles are asymmetric to the axis.

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Prediction of Void Fraction in Subcooled and Low Quality Boiling Regions

Cited by 19 publications

References 0 publications

Wall Heat Flux Partitioning Analysis for Subcooled Flow Boiling of Water-Ethanol Mixture in Conventional Channel

Wall Heat Flux Partitioning Analysis for Subcooled Flow Boiling of Water-Ethanol Mixture in Conventional Channel

Application of Quick Subchannel Analysis Method for Three-Dimensional Pin-by-Pin BWR Core Calculations

Effects of Wall Roughness and Entry Length on Void Profile in Vertical Bubbly Flow

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