Numerical Analysis of Supercritical Water Heat Transfer in Horizontal Circular Tube

2009 ◽  
Author(s):  
Bo Zhang ◽  
Jianqiang Shan ◽  
Jing Jiang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Supercritical Fluids ◽  
Supercritical Water ◽  
Circular Tube ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Heat Transfer Deterioration ◽  
Horizontal Flows ◽  
Safety And Reliability

CANDU supercritical water reactor (SCWR) offers advantages in the areas of sustainability, economics, safety and reliability and proliferation resistance. However, there is still a big deficiency in understanding and prediction of heat transfer behaviour in supercritical fluids. In this paper, heat transfer is numerically investigated on supercritical water for three-dimensional horizontal flows. Three ε-type turbulence models are tested and the numerical results are compared with experimental data. Based on the result, the standard k-ε turbulence model with enhanced wall treatment is recommended. The effect of the buoyancy and heat transfer deterioration is also analyzed, and the criteria for onset of buoyancy effects is evaluated. The quantity Gr/Re2.7 recommended by Jackson et al. (1975) gives a capacity to predict the buoyancy.

Numerical Investigation on Heat Transfer of Supercritical Water With a Variable Turbulent Prandtl Number Model

2020 ◽  
Vol 6 (3) ◽  
Author(s):  
Xiangfei Kong ◽  
Dongfeng Sun ◽  
Lingtong Gou ◽  
Siqi Wang ◽  
Nan Yang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Prandtl Number ◽  
Supercritical Fluids ◽  
Supercritical Water ◽  
Viscosity Ratio ◽  
Turbulent Viscosity ◽  
Turbulence Models ◽  
Turbulent Prandtl Number ◽  
Vertical Tubes

Abstract Turbulent Prandtl number (Prt) has a great impact on the performance of turbulence models in predicting heat transfer of supercritical fluids. Unrealistic treatment of Prt may lead to large deviations of the prediction results from experimental data under supercritical conditions. In this study, the effect of Prt on heat transfer of supercritical water was extensively studied by using shear stress transport (SST) k–ω turbulence model, and the results suggested that using the existing Prt models would lead to failures in predicting the heat transfer characteristics of supercritical water under deteriorated heat transfer (dht) conditions. A new variable Prt model was proposed with the Prt varied with pressure, turbulent viscosity ratio, and molecular Prandtl number. The new model was validated by comparing the numerical results with the corresponding experimental data, and it was found that the new variable Prt model exhibited better performance on reproducing the dht of supercritical water in vertical tubes than those of the existing Prt models.

Heat transfer deterioration to supercritical water in circular tube and annular channel

2013 ◽  
Vol 255 ◽  
pp. 97-104 ◽  
Author(s):  
Lei Liu ◽  
Zejun Xiao ◽  
Xiao Yan ◽  
Xiaokang Zeng ◽  
Yanping Huang
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Circular Tube ◽  
Annular Channel ◽  
Heat Transfer Deterioration

Numerical Investigation on Heat Transfer to Supercritical Water Flowing Upward in a 4-M Long Bare Vertical Circular Tube

2020 ◽  
Author(s):  
Dong Yang ◽  
Qixian Wu ◽  
Lin Chen ◽  
Igor Pioro
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Numerical Investigation ◽  
Supercritical Water ◽  
Wall Temperature ◽  
Nuclear Power ◽  
Circular Tube ◽  
Vertical Tube ◽  
Nuclear Power Reactor ◽  
Flow Acceleration

Abstract Thermal efficiency and safety of Generation-IV nuclear-power-reactor concept - Supercritical Water-cooled Reactor (SCWR) depend on solid knowledge of specifics of SCW thermophysical properties and heat transfer within these conditions. As a preliminary, but conservative approach to uncover these specifics is analysis of experimental data obtained in bare tubes including numerical investigation. This paper presents the numerical investigation, based on computational fluid dynamics, of the heat-transfer characteristics of SCW flow in a 4-m long circular tube (ID = 10 mm). The flow and heat-transfer mechanism of SCW in the vertical tube under the influence of buoyancy and flow acceleration are analyzed. Results of numerical simulation predict the experimental data with reasonable accuracy. The results indicated that in the region of q/G > 0.4 kJ/kg, the wall temperature distribution tends to be non-linear, and heat transfer may deteriorate. When Tb < Tpc < Tw, internal wall temperature shows peaks, which corresponds to heat-transfer deterioration. Meanwhile the position, where the deterioration occurs is continuously moved forward to the inlet as the heat flux increases. Velocity changes near the wall show an M shape according to mass conservation for the density change.

scholarly journals Numerical Investigation of Heat Transfer to Supercritical Water in Vertical Tube under Semicircular Heating Condition

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3958
Author(s):  
Zhenchuan Wang ◽  
Guoli Qi ◽  
Meijun Li
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Vertical Tube ◽  
Heating Condition ◽  
Buoyancy Effect ◽  
Uniform Heating ◽  
Three Dimensional Model ◽  
Heat Transfer Deterioration

In-depth understanding and analysis of turbulent convection heat transfer of supercritical water under semicircular heating conditions play a major role in system design and security. The inaccurate numerical results on simulating the buoyancy effect under deterioration heat transfer cases are partly attributed to the invalidity of the turbulent model. An improved turbulence model, which is validated suitable to three-dimensional model, is adopted in the present paper to numerical simulated flow and heat transfer in a vertical tube under semicircular heating condition. Heat transfer deterioration phenomenon occurs under semicircular heating condition, while the degree of deterioration is weakened due to the influence of variable physical properties and buoyancy effect. The velocity profile is distorted into “M-shape” in the heating side and present parabolic distribution in the adiabatic side, leading to different deterioration mechanisms under semicircular heating condition compared with uniform heating. The larger density difference between the heating side and the adiabatic side increases the shear stress production of turbulent kinetic energy; turbulent development is much faster recovery than the phenomenon in uniform heating condition. The results show that the semicircular heating condition can effectively alleviate the degree of heat transfer deterioration in a vertical tube.

Heat Transfer Analysis of the Surface of a Nozzle Guide Vane in a Transonic Annular Cascade

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Kasem Eid Ragab ◽  
Lamyaa El-Gabry
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Guide Vane ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Heat Transfer Analysis ◽  
Cfd Models ◽  
Commercial Code ◽  
Nozzle Guide ◽  
Annular Cascade

Abstract In the current study, a numerical analysis was performed for the heat transfer over the surface of nozzle guide vanes (NGVs) using three-dimensional computational fluid dynamics (CFD) models. The investigation has taken place in two stages: the baseline nonfilm-cooled NGV and the film-cooled NGV. A finite volume based commercial code was used to build and analyze the CFD models. The investigated annular cascade has no heat transfer measurements available; hence in order to validate the CFD models against experimental data, two standalone studies were carried out on the NASA C3X vanes, one on the nonfilm-cooled C3X vane and the other on the film-cooled C3X vane. Different modeling parameters were investigated including turbulence models in order to obtain good agreement with the C3X experimental data; the same parameters were used afterward to model the industrial NGVs.

CFD Analysis of Flow and Heat Transfer in a Direct Transfer Preswirl System

2011 ◽  
Vol 134 (3) ◽  
Author(s):  
Umesh Javiya ◽  
John W. Chew ◽  
Nicholas J. Hills ◽  
Leisheng Zhou ◽  
Mike Wilson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Turbulence Modeling ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Quantitative Agreement ◽  
Wall Turbulence ◽  
Direct Transfer ◽  
Cfd Models ◽  
Flow And Heat Transfer

The accuracy of computational fluid dynamics (CFD) for the prediction of flow and heat transfer in a direct transfer preswirl system is assessed through a comparison of CFD results with experimental measurements. Axisymmetric and three-dimensional (3D) sector CFD models are considered. In the 3D sector models, the preswirl nozzles or receiver holes are represented as axisymmetric slots so that steady state solutions can be assumed. A number of commonly used turbulence models are tested in three different CFD codes, which were able to capture all of the significant features of the experiments. A reasonable quantitative agreement with experimental data for static pressure, total pressure, and disk heat transfer is found for the different models, but all models gave results that differ from the experimental data in some respect. The more detailed 3D geometry did not significantly improve the comparison with experiment, which suggests deficiencies in the turbulence modeling, particularly in the complex mixing region near the preswirl nozzle jets. The predicted heat transfer near the receiver holes was also shown to be sensitive to near-wall turbulence modeling. Overall, the results are encouraging for the careful use of CFD in preswirl-system design.

CFD Analysis of Flow and Heat Transfer in a Direct Transfer Pre-Swirl System

2010 ◽  
Author(s):  
Umesh Javiya ◽  
John Chew ◽  
Nick Hills ◽  
Leisheng Zhou ◽  
Mike Wilson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Quantitative Agreement ◽  
Turbulence Modelling ◽  
Wall Turbulence ◽  
Direct Transfer ◽  
Cfd Models ◽  
Flow And Heat Transfer

The accuracy of computational fluid dynamics (CFD) for the prediction of flow and heat transfer in a direct transfer pre-swirl system is assessed through a comparison of CFD results with experimental measurements. Axisymmetric and three dimensional (3D) sector CFD models are considered. In the 3D sector models, the pre-swirl nozzles or receiver holes are represented as axisymmetric slots so that steady state solutions can be assumed. A number of commonly used turbulence models are tested in three different CFD codes, which were able to capture all of the significant features of the experiments. Reasonable quantitative agreement with experimental data for static pressure, total pressure and disc heat transfer is found for the different models, but all models gave results which differ from the experimental data in some respect. The more detailed 3D geometry did not significantly improve the comparison with experiment, which suggested deficiencies in the turbulence modelling, particularly in the complex mixing region near the pre-swirl nozzle jets. The predicted heat transfer near the receiver holes was also shown to be sensitive to near-wall turbulence modelling. Overall, the results are encouraging for the careful use of CFD in pre-swirl-system design.

scholarly journals Comparison of Two-Equation Turbulence Models for Prediction of Heat Transfer on Film-Cooled Turbine Blades

1997 ◽  
Author(s):  
Vijay K. Garg ◽  
Ali A. Ameri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Computer Time ◽  
Suction Surface ◽  
The Heat Transfer Coefficient

A three-dimensional Navier-Stokes code has been used to compute the heat transfer coefficient on two film-cooled turbine blades, namely the VKI rotor with six rows of cooling holes including three rows on the shower head, and the C3X vane with nine rows of holes including five rows on the shower head. Predictions of heat transfer coefficient at the blade surface using three two-equation turbulence models, specifically, Coakley’s q-ω model, Chien’s k-ε model and Wilcox’s k-ω model with Menter’s modifications, have been compared with the experimental data of Camci and Arts (1990) for the VKI rotor, and of Hylton et al. (1988) for the C3X vane along with predictions using the Baldwin-Lomax (B-L) model taken from Garg and Gaugler (1995). It is found that for the cases considered here the two-equation models predict the blade heat transfer somewhat better than the B-L model except immediately downstream of the film-cooling holes on the suction surface of the VKI rotor, and over most of the suction surface of the C3X vane. However, all two-equation models require 40% more computer core than the B-L model for solution, and while the q-ω and k-ε models need 40% more computer time than the B-L model, the k-ω model requires at least 65% more time due to slower rate of convergence. It is found that the heat transfer coefficient exhibits a strong spanwise as well as streamwise variation for both blades and all turbulence models.

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