Laminar Mixed Convection of Cold Water in a Vertical Annulus With a Heated Rotating Inner Cylinder

1992 ◽  
Vol 114 (2) ◽  
pp. 418-424 ◽  
Author(s):  
C. J. Ho ◽  
F. J. Tu
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Mixed Convection ◽  
Forced Convection ◽  
Cold Water ◽  
Convection Heat Transfer ◽  
Axial Rotation ◽  
Convection Heat ◽  
Density Inversion ◽  
Vertical Annulus

A numerical investigation is made to evaluate the perturbing effect of forced convection due to axial rotation of the inner cylinder on natural convection heat transfer of cold water with density inversion effects in a vertical cylindrical annulus. The mixed convection heat and fluid flow structures in the annulus are found to be strongly affected by the density inversion effects. The centrifugally forced convection can result in significant enhancement of the buoyant convection heat transfer of cold water with the density inversion parameter being equal to 0.4 or 0.5; thus the slow axial rotation of the inner cylinder can be a viable means for heat transfer augmentation of cold water natural convection in a vertical annulus.

Natural Convection Heat Transfer of Water Within a Horizontal Cylindrical Annulus With Density Inversion Effects

1983 ◽  
Vol 105 (1) ◽  
pp. 117-123 ◽  
Author(s):  
P. Vasseur ◽  
L. Robillard ◽  
B. Chandra Shekar
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Solutions ◽  
Cold Water ◽  
Freezing Point ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Density Inversion ◽  
Cylindrical Annulus

The effect of density inversion on steady natural convection heat transfer of cold water, between two horizontal concentric cylinders of gap width, L, is studied numerically. Water near its freezing point is characterized by a density maximum at 4°C. Numerical solutions are obtained for cylinders with nonlinear Rayleigh numbers RA ranging from 2 × 103 to 7.6 × 104, a radius ratio 1.75 ≤ ra ≤ 2.6 and an inversion parameter γ, relating the temperature for maximum density with the cavity wall temperatures, between −2 and 2. The results obtained are presented graphically in the form of streamline and isotherm contour plots. The heat transfer characteristics, velocity profiles, and local and overall Nusselt numbers are studied. The results of the present study were found qualitatively valid when compared with an experimental investigation carried out in the past.

Natural Convection Heat Transfer of Cold Water Within an Eccentric Horizontal Cylindrical Annulus

1988 ◽  
Vol 110 (4a) ◽  
pp. 894-900 ◽  
Author(s):  
C. J. Ho ◽  
Y. H. Lin
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Cold Water ◽  
Convection Heat Transfer ◽  
Orientation Angle ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Density Inversion ◽  
Cylindrical Annulus ◽  
Isothermal Cylinders

Natural convection heat transfer of cold water, encompassing a density inversion, within an eccentric horizontal annulus made of two isothermal cylinders, is numerically studied via a finite difference method. Numerical results have been obtained for an annular radius ratio 2.6 with Rayleigh number ranging from 103 to 106, the inversion parameter being 0.0 to 1.0, the eccentricity varying from 0 to 0.8, and the orientation angle of the inner cylinder between 0 and π. Results indicate that the flow patterns and heat transfer characteristics are strongly influenced by the combined effect induced by the density inversion of water and the position of the inner cylinder of the annulus. For the cases considered in the present study, a minimum in heat transfer arises with the inversion parameter between 0.4 and 0.5 depending primarily on the position of the inner cylinder.

Impairment of Local Heat Transfer of the Turbulent Mixed Convection in a Vertical Flat Plate

2018 ◽  
Author(s):  
Myeong-Seon Chae ◽  
Bum-Jin Chung
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Mixed Convection ◽  
Flat Plate ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Convection Heat ◽  
Vertical Flat Plate

The heat transfer of the buoyancy-aided turbulent mixed convective flow in a vertical flat plate was investigated experimentally. Mass transfer experiments were carried out based on the heat and mass transfer analogy. The Rayleigh numbers ranged from 1.69 × 108 to 2.11 × 1013, depending on the height of the vertical flat plate. The Reynolds numbers varied from 4,585 to 17,320 for turbulent regimes. The test results for turbulent forced convections agreed well with the forced convection correlations established by Petukhov et al. The local heat transfer rates of the turbulent mixed flow exhibited the impairment of heat transfer compared to the forced convection and non-monotonous behavior along the axial position due to buoyancy effect. The local minimum heat transfer was 38.6% lower than the forced convection heat transfer. The turbulent mixed convection heat transfer is affected by the height of vertical plate.

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