A mathematic model of two-phase flow taking account of sub-cooled boiling, condensation, and void flashing
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S. Y. Jiang
Abstract
Based on a physical model of the test loop HRTL-5 simulating the 5 MW nuclear heating reactor, a drift-flux model of two-phase flow has been derived, in which the sub-cooled boiling and saturated boiling in the heated section, condensation and void flashing in the adiabatic riser etc, are taken into account. It is suitable to investigate the natural circulation two-phase flow, especially at heating reactor conditions. By introducing the concept of condensation boundary layer, a condensation formula has been derived and complemented into the drift-flux model, which was used to investigate the behavior of the HRTL-5 in our previous research works. Based on the mathematical model, a computer program has been developed. At first, through comparing the calculations with the experimental results, the parameters in the two-phase drift-flux model have been determined. Then calculations on the flow characteristics of HRTL-5 have been performed, including the simulation of the mass flow rate and the distribution of various physical variables. At last, the characteristic curves of natural circulation have been simulated; thereby, also useful experiences have been acquired.
Abstract
Auf der Basis eines mathematischen Modells der Testanlage HRTL-5, die einen 5 MW Heizreaktor simuliert, wurde ein Drift-Flux-Modell der Zwei-Phasen Strömung entwickelt, unter Berücksichtigung von unterkühltem Blasensieden im Heizbereich, Kondensation und Blasenverdampfung im adiabatischen Steigrohr usw. Es ist wichtig, die Zwei-Phasen-Strömung in einem System mit Naturumlauf zu untersuchen, insbesondere unter den Bedingungen eines Heizreaktors. Durch Einführung des Konzepts einer Kondensationsgrenzschicht wurde eine Kondensationsformel entwickelt und in das Drift-Flux-Modell integriert, das bereits zur Untersuchung des Verhaltens der HRTL-Testanlage in den vorangegangenen Forschungsarbeiten verwendet wurde. Auf der Grundlage des mathematischen Modells wurde ein Computerprogramm entwickelt. Zuerst wurden die Parameter des Zwei-Phasen-Drift-Flux-Modells bestimmt durch Vergleich der Rechenergebnisse mit den experimentellen Ergebnissen. Dann wurden Berechnungen der Strömungseigenschaften der HRTL-Testanlage durchgeführt, einschließlich der Simulation der Massenströmungsdichte und der Verteilung verschiedener physikalischer Variablen. Zuletzt wurden die charakteristischen Kurven des Naturumlaufs simuliert und dabei wichige Erfahrungen gesammelt.
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Project supported by Trans ± Century Training Program Foundation for the Talents by the Ministry of Education.
List of symbols
- α =
void fraction
- ρ =
density
- p =
pressure
pressure drop along the direction of z
local pressure drop
friction pressure drop
gravity pressure drop
- u =
velocity
- h =
specific enthalpy
- U =
perimeter of heated rods
- q =
heat flux density per unit area
- A =
flow area
- Qc =
heat condensed from vapor to water per unit length
- Ψ =
fraction of heat-generated vapor at surface of heated rod
- τ =
rate of vapor condensation or generation
- C0 =
distribution parameter in drift model
- uvj =
slippage velocity in drift model
- J =
volume flow velocity of two-phase mixture
- G =
mass flow rate
- T =
temperature
- ur =
relative velocity of bubble and liquid
- δ =
thickness of condensation boundary layer
- N =
enthalpy flow rate
- λ =
coefficient of the liquid heat conduction
- Rb =
radius of sub-cooled steam bubble
- nb =
bubbles per unit length
- cp =
specific heat capacity at const pressure
- r =
latent heat
- ule =
inlet velocity of liquid
- □T =
temperature difference or sub-cooling
- t =
time
Subscripts
- t =
sensible heat
- c =
latent heat
- l =
liquid
- v =
vapor
- lv =
difference between liquid and steam
- L =
local
- F =
flow resistance
- G =
gravity pressure drop
- S =
saturation
- in =
inlet
- y =
distance from the steam-liquid interface
References
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© 2003 Carl Hanser Verlag, München
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Articles in the same Issue
- Frontmatter
- Summaries
- Summaries/Kurzfassungen
- Biokinetic model for the calculation of dose coefficients for oral and intravenous administration of 14C labeled drugs
- First nuclear activation experiments using the new accelerator NUCLOTRON in Dubna
- Charge fragmentation in cosmic radiation – and the question of physical anomalons
- Measurements of gamma and neutron flux spectra in iron-water configurations
- Experimental and analytical investigation of the ITU TRIGA Mark-II reactor core
- Books. Bücher
- Books. Bücher
- Experimental studies on condensation of steam mixed with noncondensable gas inside the vertical tube in a pool filled with subcooled water
- Books. Bücher
- Books. Bücher
- A mathematic model of two-phase flow taking account of sub-cooled boiling, condensation, and void flashing
- Books. Bücher
- A new approach to authorisation in the field of radiological protection
- Experimental study on natural convection in the vertical enclosure of a double coaxial cylinder
- Technical Note
- Integral nucleus-nucleus cross-sections
- Books. Bücher
- Books. Bücher
- Technical Note
- Fermat’s optics in nuclear materials
- Advances
- Patent
- Patent
- Note. Mitteilung
