Free Convection Heat Transfer Across Inclined Honeycomb Panels

1977 ◽  
Vol 99 (1) ◽  
pp. 86-91 ◽  
Author(s):  
R. L. D. Cane ◽  
K. G. T. Hollands ◽  
G. D. Raithby ◽  
T. E. Unny
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Free Convection ◽  
Convection Heat Transfer ◽  
Correlation Equation ◽  
Base Flow ◽  
Convection Heat ◽  
Radiative Coupling ◽  
Aspect Ratios ◽  
Free Convection Heat

Experimentally obtained Nusselt number-Rayleigh number plots are presented for free convective heat transfer across honeycomb panels, heated from below, and inclined with respect to the horizontal at angles of 0, 30, 45, 60, and 90 deg. Aspect ratios of honeycomb cells of 2, 3, 4, and 5 are included; the fluid contained in the cells is air. Substantial suppression of free convection is observed when compared with an air layer of the same depth but not containing a honeycomb. Heat transfer associated with the base flow is found to be of only moderate importance at angles near horizontal, but of considerable consequence for angles near the vertical. The honeycomb walls used were partly transparent to thermal radiation, and a strong radiative coupling is indicated. A correlation equation for the Nusselt number, valid over part of the experimental range, is presented.

An Experimental Study on the Effect of Partition Angle on Free Convection Heat Transfer in a Partition Cavity by Laser Interferometry Method

2010 ◽  
Author(s):  
Tooraj Yousefi ◽  
Sajjad Mahmoodi Nezhad ◽  
Masood Bigharaz ◽  
Saeed Ebrahimi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Free Convection ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Laser Interferometry ◽  
Heated Wall ◽  
Convection Heat ◽  
Free Convection Heat

Steady state two-dimensional free convection heat transfer in a partitioned cavity with adiabatic horizontal and isothermally vertical walls and an adiabatic partition has been investigated experimentally. The experiments have been carried out using a Mach-Zehnder interferometer. The effects of the angel of the adiabatic partition and Rayleigh number on the heat transfer from the heated wall are investigated. Experiments are performed for the values of Rayleigh number based on the cavity side length in the range between 1.5×105 to 4.5×105 and various angle of the partition with respect to horizon from 0° to 90°. The results indicate that at each angle of the adiabatic partition, by increasing the Rayleigh number, the average Nusselt number and heat transfer increase and at each Rayleigh number, the maximum and the minimum heat transfer occur at θ=45° and θ=90°, respectively. A correlation based on the experimental data for the average Nusselt number of the heated wall as a function of Rayleigh number and the angel of the adiabatic partition is presented in the aforementioned ranges.

On Gaseous Free-Convection Heat Transfer With Well-Defined Boundary Conditions

2000 ◽  
Vol 122 (4) ◽  
pp. 661-668 ◽  
Author(s):  
M. R. D. Davies ◽  
D. T. Newport ◽  
T. M. Dalton
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Free Convection ◽  
Boundary Conditions ◽  
Convection Heat Transfer ◽  
Boussinesq Approximation ◽  
Horizontal Cylinder ◽  
Convection Heat ◽  
Variable Property ◽  
Free Convection Heat

The scaling of free convection heat transfer is investigated. The nondimensional groups for Boussinesq and fully compressible variable property free convection, driven by isothermal surfaces, are derived using a previously published novel method of dimensional analysis. Both flows are described by a different set of groups. The applicability of each flow description is experimentally investigated for the case of the isothermal horizontal cylinder in an air-filled isothermal enclosure. The approach taken to the boundary conditions differs from that of previous investigations. Here, it is argued that the best definition of the boundary conditions is achieved for heat exchange between the cylinder and the enclosure rather than the cylinder and an arbitrarily chosen fluid region. The enclosure temperature is shown both analytically and experimentally to affect the Nusselt number. The previously published view that the Boussinesq approximation has only a limited range of application is confirmed, and the groups derived for variable property compressible free convection are demonstrated to be correct experimentally. A new correlation for horizontal cylinder Nusselt number prediction is presented. [S0022-1481(00)01604-2]

scholarly journals Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2909
Author(s):  
Dorota Sawicka ◽  
Janusz T. Cieśliński ◽  
Slawomir Smolen
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Heat Transfer Performance ◽  
Convection Heat Transfer ◽  
Correlation Equation ◽  
Horizontal Cylinder ◽  
Al2o3 Nanoparticles ◽  
Convection Heat ◽  
Number Range ◽  
Free Convection Heat

The results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 × 104 ≤ Ra ≤ 1.3 × 106 and the Prandtl (Pr) number varied from 4.4 to 176. Alumina (Al2O3) nanoparticles were tested at the mass concentrations of 0.01, 0.1 and 1%. Enhancement as well as deterioration of heat transfer performance compared to the base fluids were detected depending on the composition of the nanofluid. Based on the experimental results obtained, a correlation equation that describes the dependence of the average Nusselt (Nu) number on the Ra number, Pr number and concentration of nanoparticles is proposed.

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.

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