Experimental examination of heat removal limitation of screw cooling tube at high pressure and temperature conditions

Ezato, Koichiro; Suzuki, Satoshi; Dairaku, M.; Akiba, Masato

doi:10.1016/j.fusengdes.2005.06.360

Cited by 13 publications

(3 citation statements)

References 12 publications

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“…Ezato et al [14] evaluated the CHFs of an M10 screw tube with a 1.5 mm pitch at pressure, inert bulk temperature, and flow velocity ranges of 2-4 MPa, 30 • C-100 • C, and 2.2-19.5 m s −1 , respectively. They reported that the forced convection heat transfer coefficient (HTC) performance of the screw tube in the SP regime was twice as good as that of a plain tube.…”

Section: Introductionmentioning

confidence: 99%

Study on onset of nucleate boiling with screw tube for fusion reactor application

Lim

Park

2022

Nucl. Fusion

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The onset of nucleate boiling (ONB) is the point at which the heat transfer mechanism in fluids changes and is one of the thermo-hydraulic factors that must be considered when establishing a cooling system operation strategy. Because the high heat flux of several MW/m2, which is loaded within a tokamak, is applied under a one-side heating condition, it is necessary to determine a correlative relation that can predict ONB under special heating conditions. In this study, the ONB of a one-side-heated screw tube was experimentally analyzed via a subcooled flow boiling experiment. The helical nut structure of the screw tube flow path wall allows for improved heat transfer performance relative to smooth tubes, providing a screw tube with a 53.98% higher ONB than a smooth tube. The effects of the system parameters on the ONB heat flux were analyzed based on the changes in the heat transfer mechanism, with the results indicating that the flow rate and degree of subcooling are proportional to the ONB heat flux because increasing these factors improves the forced convection heat transfer and increases the condensation rate, respectively. However, it was observed that the liquid surface tension and latent heat decrease as the pressure increases, leading to a decrease in the ONB heat flux. An evaluation of the predictive performance of existing ONB correlations revealed that most have high error rates because they were developed based on ONB experiments on micro-channels or smooth tubes and not under one-side high heat load conditions. To address this, we used dimensional analysis based on Python code to develop new ONB correlations that reflect the influence of system parameters.

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Section: Introductionmentioning

confidence: 99%

Study on onset of nucleate boiling with screw tube for fusion reactor application

Lim

Park

2022

Nucl. Fusion

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“…Raffray [5] studied the effects of armour thickness of a carbon-fibre composite (CFC) monoblock on its peaking factors, but the effects of flow parameters on peaking factors were not considered in their papers. Ezato [6,8] proposed that the peaking factor of an oxygen-free high-conductivity copper (OFHC-Cu) screw tube varies from 1.39 to 1.70 depending on the coolant pressure, velocity and temperature, but the details of influence rules were not given. J. Boscary [9] gave the peaking factors of nine different tubes and the results showed that there were significant differences of peaking factors between different structures or different materials of tubes.…”

Section: Introductionmentioning

confidence: 99%

Numerical Calculation of the Peaking Factor of a Water-Cooled W/Cu Monoblock for a Divertor

Han

Hai-ping

Zhang

et al. 2015

Plasma Sci. Technol.

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In order to accurately predict the incident critical heat flux (ICHF, the heat flux at the heated surface when CHF occurs) of a water-cooled W/Cu monoblock for a divertor, the exact knowledge of its peaking factors (fp) under one-sided heating conditions with different design parameters is a key issue. In this paper, the heat conduction in the solid domain of a water-cooled W/Cu monoblock is calculated numerically by assuming the local heat transfer coefficients (HTC) of the cooling wall to be functions of the local wall temperature, so as to obtain fp. The reliability of the calculation method is validated by an experimental example result, with the maximum error of 2.1% only. The effects of geometric and flow parameters on the fp of a water-cooled W/Cu monoblock are investigated. Within the scope of this study, it is shown that the fp increases with increasing dimensionless W/Cu monoblock width and armour thickness (the shortest distance between the heated surface and Cu layer), and the maximum increases are 43.8% and 22.4% respectively. The dimensionless W/Cu monoblock height and Cu thickness have little effect on fp. The increase of Reynolds number and Jakob number causes the increase of fp, and the maximum increases are 6.8% and 9.6% respectively. Based on the calculated results, an empirical correlation on peaking factor is obtained via regression. These results provide a valuable reference for the thermal-hydraulic design of water-cooled divertors.

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“…Therefore, numerical simulation becomes an effective way of research on subcooled boiling heat transfer characteristics of the water-cooled W/Cu divertor. Koichiro [6] , Araki [7] and Boscary [8] calculated the temperature distribution of the water-cooled divertor by assuming the local heat transfer coefficients (HTC) of the cooling wall to be functions of local wall temperature or heat flux, and only the heat conduction in solid was calculated. The important parameters that were related to subcooled boiling, such as void fraction, were not obtained.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation on Subcooled Boiling Heat Transfer Characteristics of Water-Cooled W/Cu Divertors

Han

Hai-ping

Zhang

2015

Plasma Sci. Technol.

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In order to realize safe and stable operation of a water-cooled W/Cu divertor under high heating condition, the exact knowledge of its subcooled boiling heat transfer characteristics under different design parameters is crucial. In this paper, subcooled boiling heat transfer in a water-cooled W/Cu divertor was numerically investigated based on computational fluid dynamic (CFD). The boiling heat transfer was simulated based on the Euler homogeneous phase model, and local differences of liquid physical properties were considered under one-sided high heating conditions. The calculated wall temperature was in good agreement with experimental results, with the maximum error of 5% only. On this basis, the void fraction distribution, flow field and heat transfer coefficient (HTC) distribution were obtained. The effects of heat flux, inlet velocity and inlet temperature on temperature distribution and pressure drop of a water-cooled W/Cu divertor were also investigated. These results provide a valuable reference for the thermal-hydraulic design of a water-cooled W/Cu divertor.

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Experimental examination of heat removal limitation of screw cooling tube at high pressure and temperature conditions

Cited by 13 publications

References 12 publications

Study on onset of nucleate boiling with screw tube for fusion reactor application

Study on onset of nucleate boiling with screw tube for fusion reactor application

Numerical Calculation of the Peaking Factor of a Water-Cooled W/Cu Monoblock for a Divertor

Numerical Simulation on Subcooled Boiling Heat Transfer Characteristics of Water-Cooled W/Cu Divertors

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