New dimensionless correlation-equations for laminar free convection heat transfer in real gases with high wall-fluid temperature differences

2004 ◽  
Vol 43 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Massimo Corcione ◽  
Donato Maria Fontana
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Convection Heat Transfer ◽  
Fluid Temperature ◽  
Correlation Equations ◽  
Convection Heat ◽  
Free Convection Heat

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.

Effect of Aspect Ratio and Tube Orientation on Free Convection Heat Transfer to Water and Mercury in Enclosed Circular Tubes

1961 ◽  
Vol 83 (1) ◽  
pp. 87-93 ◽  
Author(s):  
Floyd W. Larsen ◽  
James P. Hartnett
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Convection Heat Transfer ◽  
Temperature Fluctuations ◽  
Heat Fluxes ◽  
Radius Ratio ◽  
Uniform Heat Flux ◽  
Fluid Temperature ◽  
Convection Heat ◽  
Free Convection Heat

Free convection heat transfer to water and to mercury in a circular tube closed at the bottom end, open to a cooled reservoir at the top, and heated through the wall with a uniform heat flux, has been investigated with emphasis on the effect of length-to-radius ratio and tube inclination. Dimensionless wall and fluid temperatures are presented for several tube inclinations over a range of imposed dimensionless heat fluxes to a tube of length-to-radius ratio 14.6; these results are compared to earlier measurements in a tube of length-to-radius ratio 21.0. Over the range of the investigation the flow was apparently in fully mixed turbulent motion, as evidenced by the large fluid temperature fluctuations recorded during the tests. Inclination of the tube was found to result in a considerable decrease in temperature fluctuations and a corresponding increase in heat transfer above that observed with the tube axis vertical.

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