Heat transfer in nucleate boiling outside horizontal tube bundles (1st report, Experimental investigation on tube bundle effect)

Experiments are carried out to investigate the Onset of Nucleate Boiling (ONB) of refrigerant R-113 through vertical and inclined tube-bundle channels. Several methods are adopted to ascertain ONB in the experiments, and their differences are analyzed. The experiments show that the results of ONB estimation from the visualization experiment, ONB estimation from the wall temperature and that from the heat transfer coefficient are uniform. The influences of heat flux, mass flow rate, the geometric dimensions and inclination angle of the tube-bundle channels on the ONB height are explored in detail. On the foundation of the comparisons and analyses, an equation is put forward for calculating the ONB height in tube-bundle channels, which has a good accordance with the experimental results.

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A New Heat Transfer Correlation and Flow Regime Map for Tube Bundles

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2906469 ◽

1990 ◽

Vol 112 (1) ◽

pp. 150-156 ◽

Cited By ~ 3

Author(s):

Y. A. Hassan ◽

T. K. Blanchat

Keyword(s):

Heat Transfer ◽

Flow Regime ◽

Steam Generator ◽

Tube Bundle ◽

Nucleate Boiling ◽

Heat Transfer Correlation ◽

Transfer Coefficients ◽

Tube Bundles ◽

Regime Map ◽

Flow Regime Map

A RELAP5/MOD2 computer code model for a once-through steam generator has been developed. The calculated heat transfer in the nucleate boiling flow was underpredicted as shown by a predicted superheat of only 11°C (20°F), whereas plant values range from 22–30°C (40–60°F). Existing heat transfer correlations used in thermal-hydraulic computer codes do not provide accurate predictions of the measurement-derived secondary convective heat transfer coefficients for steam generators because they were developed for flow inside tubes, not tube bundles. The RELAP5/MOD2 flow regime map was modified to account for flow across bundles. This modified flow regime map predicts better transition criteria between bubbly-to-slug and slug-to-annular flow. Consequently, improved saturated conditions for the fluid flow at the entrance to the boiler were obtained. A modified Chen-type heat transfer correlation was developed to predict the boiling heat transfer for steam generator tube bundle geometries. This correlation predicts better superheat.

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Different Type Tube Bundle Heat Transfer to Vertical Foam Flow

ASME 5th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2007-30070 ◽

2007 ◽

Author(s):

Jonas Gylys ◽

Stasys Sinkunas ◽

Tadas Zdankus ◽

Vidmantas Giedraitis

Keyword(s):

Heat Transfer ◽

Experimental Investigation ◽

Flow Velocity ◽

Void Fraction ◽

Tube Bundle ◽

Auxiliary Equipment ◽

Foam Flow ◽

Flow Parameters ◽

Tube Bundles ◽

Foam Generator

Gas-liquid foam due to especially large inter-phase contact surface can be used as a coolant. An experimental investigation of the staggered and in-line tube bundles’ heat transfer to the vertically upward and downward laminar foam flow was performed. The experimental setup consisted of the foam generator, vertical experimental channel, tube bundles, measurement instrumentation and auxiliary equipment. It was determined dependency of heat transfer intensity on flow parameters: flow velocity, direction of flow, volumetric void fraction of foam and liquid drainage from foam. Apart of this, influence of tube position in the bundle to heat transfer was investigated. Foam flow structure, distribution of the foam’s local void fraction and flow velocity in cross-section of the channel were the main factors which influenced on heat transfer intensity of the different tubes. Experimental investigation showed that the heat transfer intensity of the frontal and further tubes of the bundles to vertical foam flow is different in comparison with one-phase fluid flow. The results of the experimental investigation are presented in this paper.

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