Calculation of dryout and post-dryout heat transfer for tube geometry

Hoyer, N.

doi:10.1016/s0301-9322(97)00057-8

Cited by 64 publications

(13 citation statements)

References 11 publications

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“…For the bubbly flow, the droplet phase fraction is set to zero, the vapour phase fraction is evaluated from the drift flux model [1] and the liquid phase fraction is obtained by difference. For the slug flow regime, the droplet phase fraction is again set to zero and the vapour and the liquid phase fractions are obtained from the slug flow model of Orell and Rembrand [15]. For annular flow, the entrained liquid fraction is determined from the correlation of Govan [10].…”

Section: Analysis Of the Pressure Drop Datamentioning

confidence: 99%

“…For the bubbly and the post-dryout phases, the frictional pressure gradient is estimated from the densities and superficial velocities of the mixture of liquid/bubble or gas/droplet phases, respectively. For the slug flow, the frictional pressure gradient is obtained directly from the Orell and Rembrand model [15] while for the annular flow regime, the frictional pressure gradient is obtained as part of the triangular relationship. The overall set of flow regime criteria and evaluation methods for the phase fraction and the frictional component of the pressure drop are summarized in Table 2.…”

Section: Analysis Of the Pressure Drop Datamentioning

confidence: 99%

“…A case in point is the annular flow model which was originally developed based on adiabatic air-water data but which has since been applied successfully to non-adiabatic systems at pressures up to 70 bar [9]. However, recent studies [15,16] have shown that extension of the model to much higher pressures (say, greater than 100 bar for a steam-water system) was not straightforward and that correction factors for both entrainment and deposition rates had to be incorporated to obtain good results.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Pressure drop studies on two-phase flow in a uniformly heated vertical tube at pressures up to the critical point

Vijayarangan

Jayanti

Balakrishnan

2007

International Journal of Heat and Mass Transfer

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Section: Analysis Of the Pressure Drop Datamentioning

confidence: 99%

Section: Analysis Of the Pressure Drop Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Pressure drop studies on two-phase flow in a uniformly heated vertical tube at pressures up to the critical point

Vijayarangan

Jayanti

Balakrishnan

2007

International Journal of Heat and Mass Transfer

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“…The phenomenological (mechanistic) models for LFD have been suggested by various investigators. Representative models are due to Levy [2], Saito et al [3], Katto [4], Sugawara [5] and Hoyer [6] with different level of success. Over the years there have been significant improvements in the mechanistic prediction of dryout.…”

Section: Introductionmentioning

confidence: 99%

A Mechanistic Approach for the Prediction of Critical Power in BWR Fuel Bundles

Chandraker

Vijayan

Sinha

et al. 2012

JPES

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The critical power corresponding to the Critical Heat Flux (CHF) or dryout condition is an important design parameter for the evaluation of safety margins in a nuclear fuel bundle. The empirical approaches for the prediction of CHF in a rod bundle are highly geometric specific and proprietary in nature. The critical power experiments are very expensive and technically challenging owing to the stringent simulation requirements for the rod bundle tests involving radial and axial power profiles. In view of this, the mechanistic approach has gained momentum in the thermal hydraulic community. The Liquid Film Dryout (LFD) in an annular flow is the mechanism of CHF under BWR conditions and the dryout modeling has been found to predict the CHF quite accurately for a tubular geometry. The successful extension of the mechanistic model of dryout to the rod bundle application is vital for the evaluation of critical power in the rod bundle. The present work proposes the uniform film flow approach around the rod by analyzing individual film of the subchannel bounded by rods with different heat fluxes resulting in different film flow rates around a rod and subsequently distributing the varying film flow rates of a rod to arrive at the uniform film flow rate as it has been found that the liquid film has a strong tendency to be uniform around the rod. The FIDOM-Rod code developed for the dryout prediction in BWR assemblies provides detailed solution of the multiple liquid films in a subchannel. The approach of uniform film flow rate around the rod simplifies the liquid film cross flow modeling and was found to provide dryout prediction with a good accuracy when compared with the experimental data of 16, 19 and 37 rod bundles under BWR conditions. The critical power has been predicted for a newly designed 54 rod bundle of the Advanced Heavy Water Reactor (AHWR). The selected constitutive models for the droplet entrainment and deposition rates validated for the dryout in tube were also found to perform well for the rod bundle under BWR conditions.

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“…At the point the heat transfer coefficient in core begins to deteriorate and finally results in fuel failure. The heat flux is commonly referred to as departure from nucleate boiling (DNB) or critical heat flux (CHF) (Hoyer, 1998;Katto, 1994). One of the most important requirements in the design of PWR is to avoid the occurrence of CHF.…”

Section: Introductionmentioning

confidence: 99%