Free Convection Heat Transfer From Spheroids

1976 ◽  
Vol 98 (3) ◽  
pp. 452-458 ◽  
Author(s):  
G. D. Raithby ◽  
A. Pollard ◽  
K. T. G. Hollands ◽  
M. M. Yovanovich
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Large Range ◽  
Convection Heat Transfer ◽  
Prolate Spheroid ◽  
Correlation Equations ◽  
Transfer Rates ◽  
Oblate Spheroids ◽  
Free Convection Heat ◽  
Rayleigh Numbers

Measurements of the heat transfer by free convection from isothermal spheroids to air are reported. The range of Rayleigh number, Ra, covered was sufficiently large that both thick boundary layer effects (at low Ra) and turbulence (at high Ra) affect the heat transfer. Data are reported for one prolate spheroid and two oblate spheroids. The results of an approximate method of analysis, which accounts for both thick boundary layers and turbulence, are also given. These are compared to the present measurements, and to earlier measurements for spheres. Excellent agreement with experiment is found. Correlation equations, from which average heat transfer rates can be calculated, are also given. These are thought to be valid at all Rayleigh numbers over a large range of eccentricity.

scholarly journals Free Convection Heat Transfer from Horizontal Cylinders

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 559
Author(s):  
Janusz T. Cieśliński ◽  
Slawomir Smolen ◽  
Dorota Sawicka
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Free Convection ◽  
Convection Heat Transfer ◽  
Horizontal Tube ◽  
Correlation Equations ◽  
Convection Heat ◽  
Number Range ◽  
Heated Cylinder ◽  
Free Convection Heat

The results of experimental investigation of free convection heat transfer in a rectangular container are presented. The ability of the commonly accepted correlation equations to reproduce present experimental data was tested as well. It was assumed that the examined geometry fulfils the requirement of no-interaction between heated cylinder and bounded surfaces. In order to check this assumption recently published correlation equations that jointly describe the dependence of the average Nusselt number on Rayleigh number and confinement ratios were examined. As a heat source served electrically heated horizontal tube immersed in an ambient fluid. Experiments were performed with pure ethylene glycol (EG), distilled water (W), and a mixture of EG and water at 50%/50% by volume. A set of empirical correlation equations for the prediction of Nu numbers for Rayleigh number range 3.6 × 104 < Ra < 9.2 × 105 or 3.6 × 105 < Raq < 14.8 × 106 and Pr number range 4.5 ≤ Pr ≤ 160 has been developed. The proposed correlation equations are based on two characteristic lengths, i.e., cylinder diameter and boundary layer length.

Electrostatic Cooling of a Horizontal Cylinder

1991 ◽  
Vol 113 (3) ◽  
pp. 544-548 ◽  
Author(s):  
M. E. Franke ◽  
L. E. Hogue
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Convection Heat Transfer ◽  
Power Input ◽  
Horizontal Cylinder ◽  
Transfer Rates ◽  
Heated Cylinder ◽  
Free Convection Heat ◽  
Positively Charged ◽  
Corona Wind

The effects of corona wind on the heat transfer rate from a heated horizontal cylinder are described. Corona discharge and a corona wind are developed when a high voltage is applied to an electrode (emitter) near a grounded surface. In this study the corona wind is directed toward the lower region of the grounded cylinder by placing either a positively charged single-wire emitter or multipoint emitter parallel to and directly below the heated cylinder. Heat transfer rates from the heated cylinder under free convection conditions with and without a corona wind are obtained by measuring the power input to the cylinder. Free convection rates are also obtained from interferometer photographs. Free convection heat transfer rates are increased several times by the corona wind.

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