The Distribution Parameter C0 in the Drift Flux Modeling of Forced Convective Boiling (original) (raw)
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PROCEEDINGS OF THE INTERNATIONAL ENGINEERING RESEARCH CONFERENCE - 12TH EURECA 2019
Saturated flow boiling have many applications in multiphase flow equipment such as boilers and evaporators. Occurrence and movement of bubbles is an important aspect as far as saturated boiling is concerned since the bubbles can cause significant effect on the heat transfer. Also, flow boiling heat transfer coefficient (HTC) is an important parameter as it is a vital term in calculating the effective heat transfer. So modelling of saturated boiling which considers effect of bubble characteristics is of great importance. This paper deals with calculating the bubble characteristics such as bubble departure diameter, bubble departure frequency and active nucleation site density of flow of refrigerant R-134a using correlations from Lie et. al. [4] and implementing the same in the open source CFD tool OpenFOAM. The paper also validates the variation of flow
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The information on heat transfer and especially on the void fraction in the reactor core under subcooled conditions is very important for the water-cooled nuclear reactors, because of its influence upon the reactivity of the system. This paper gives a short owerview of subcooled boiling phenomenon and indicates the simplifications made by the RELAP5 model of subcooled boiling. RELAP5/MOD3.2 calculations were compared with simple one-dimensional models and with high-pressure Bartolomey experiments [8]. Nomenclature Greek letters Cfspecific heat of the fluid, J/kgK p density, kg/m C constant y/_ parameter in (eq.5) d bubble diameter /-_ volumetric mass exchange rate, kg/ms Fconvective factor from Chen's correlation AT$ai _ w a l l s u p e rheat, Tw-Tsal K G -mass flux, kg/m s ^ _ u i d s u b c o o l l T TK kfthermal conductivity, W/Mk henthalpy, J/kg Subscripts hf0 heat transfer coefficient to the single r_ £j ^ phase liquid, W/mK (eq.5,6) J _ Nu Nusselt number SQt Pe-Peclet numbe...
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CFD Modeling of Subcooled Flow Boiling for Nuclear Engineering Applications
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In this work a general-purpose CFD code CFX-5 was used for simulations of subcooled flow boiling. The subcooled boiling model, available in a custom version of CFX-5, uses a special treatment of the wall boiling boundary, which assures the grid invariant solution. The simulation results have been validated against the published experimental data [1] of highpressure flow boiling in a vertical pipe covering a wide range of conditions (relevant to the pressurized water reactor). In general, a good agreement with the experimental data has been achieved. To adequately predict the lateral distribution of two-phase flow parameters, the modelling of two-phase flow turbulence and non-drag forces under wall boiling conditions have been also investigated in the paper.
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