Heat transfer response of free convection flow from a vertical heated plate to an oscillating surface heat flux

1998 ◽  
Vol 126 (1-4) ◽  
pp. 101-113 ◽  
Author(s):  
M. A. Hossain ◽  
S. K. Das ◽  
D. A. S. Rees
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Free Convection ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Convection Flow ◽  
Heated Plate ◽  
Free Convection Flow

Effect of Edge Conditions on Natural Convective Heat Transfer From a Narrow Vertical Flat Plate With a Uniform Surface Heat Flux

2007 ◽  
Author(s):  
Patrick H. Oosthuizen ◽  
Jane T. Paul
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Surface Heat Flux ◽  
Three Dimensional ◽  
Surface Heat ◽  
Heated Plate ◽  
Two Dimensional ◽  
Adiabatic Surface

Two-dimensional natural convective heat transfer from vertical plates has been extensively studied. However, when the width of the plate is relatively small compared to its height, the heat transfer rate can be greater than that predicted by these two-dimensional flow results. Because situations that can be approximately modelled as narrow vertical plates occur in a number of practical situations, there exists a need to be able to predict heat transfer rates from such narrow plates. Attention has here been given to a plate with a uniform surface heat flux. The magnitude of the edge effects will, in general, depend on the boundary conditions existing near the edge of the plate. To examine this effect, two situations have been considered. In one, the heated plate is imbedded in a large plane adiabatic surface, the surfaces of the heated plane and the adiabatic surface being in the same plane while in the second there are plane adiabatic surfaces above and below the heated plate but the edge of the plate is directly exposed to the surrounding fluid. The flow has been assumed to be steady and laminar and it has been assumed that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces, this having been treated by using the Boussinesq approach. It has also been assumed that the flow is symmetrical about the vertical centre-plane of the plate. The solution has been obtained by numerically solving the full three-dimensional form of the governing equations, these equations being written in terms of dimensionless variables. Results have only been obtained for a Prandtl number of 0.7. A wide range of the other governing parameters have been considered for both edge situations and the conditions under which three dimensional flow effects can be neglected have been deduced.

Thermal Behavior of Double Glass Window Filled with Absorbing and Non-Absorbing Gas

2013 ◽  
Vol 805-806 ◽  
pp. 1603-1611 ◽  
Author(s):  
Chun Li Tang ◽  
Xiao Wei Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Solar Radiation ◽  
Free Convection ◽  
Surface Heat Flux ◽  
Radiation Flux ◽  
Surface Heat ◽  
Solar Radiation Flux ◽  
Surface Heat Transfer Coefficient

This paper presents a radiant model based on the radiant resistance analysis theory and the results of numerical simulations of double glass window. The two-dimensional steady state model is formulated based upon the radiation and free convection heat transfer at different external and internal ambient conditions.The properties of glass which change with incident wavelength are also considered. Specifically, air and CO2 are used as the medium in the 8mm and 10mm cavity of the double glass window, respectively. Several parameters, including transmitted solar radiation flux, temperature distribution, surface heat transfer coefficient for free convection and total surface heat flux are calculated. The results show that transmitted solar radiation flux is slightly lower when filled with CO2 in the cavity than with air due to their absorption difference. Also, the temperature of gas closing to internal glass sheet and the total surface heat flux of internal glass sheet are decreased when filled with CO2 than with air, although the surface heat transfer coefficient is slightly higher when it is CO2. .The temperature variation curves show that less heat flows into the room when filled with CO2 than air in double glass window.

Vortex Instability of Free Convection Flow Over Horizontal and Inclined Surfaces

1982 ◽  
Vol 104 (4) ◽  
pp. 637-643 ◽  
Author(s):  
T. S. Chen ◽  
K. L. Tzuoo
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Surface Heat ◽  
Convection Flow ◽  
Neutral Stability ◽  
Free Convection Flow ◽  
Vortex Instability ◽  
Surface Heat Transfer ◽  
Wide Range ◽  
Prandtl Numbers

The vortex instability characteristics of laminar free convection flow over horizontal and inclined isothermal surfaces are studied analytically by linear theory. As a prelude to the analysis, the effects of the angle of inclination on the main flow and thermal fields are re-examined by a new approach. Numerical results are presented for wall shear stress, surface heat transfer, neutral stability curve, and critical Grashof number for Prandtl numbers of 0.7 and 7 over a wide range of angles of inclination, φ, from the horizontal. It is found that as the angle of inclination increases the rate of surface heat transfer increases, whereas the susceptibility of the flow to the vortex mode of instability decreases. The present study provides new vortex instability results for small angles of inclination (φ≤30 deg) and more accurate results for large angles of inclination (φ ≥ 30 deg) than previous studies. The present results are also compared with available wave instability results.

scholarly journals EFFECT OF NON-UNIFORM HEAT SOURCE AND RADIATION ON UNSTEADY MHD FREE CONVECTION FLOW PAST AN INFINITE HEATED VERTICAL PLATE IN POROUS MEDIUM

2020 ◽  
Vol 9 (4) ◽  
pp. 219
Author(s):  
PRATIBHA MISHRA ◽  
SWETA TRIPATHI
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Source ◽  
Free Convection ◽  
Skin Friction ◽  
Time Dependent ◽  
Convection Flow ◽  
Heated Plate ◽  
Free Convection Flow ◽  
Uniform Heat

Influence of radiation and non-uniform heat source on unsteady, magneto-hydrodynamic free convection flow of viscous incompressible fluid past an infinite vertical heated plate embedded in porous medium of an optically thin environment with time dependent suction and viscous dissipation is investigated in this paper. Analytical solutions of the coupled non-linear equations are obtained for the velocity field and temperature distribution using oscillating time-dependent perturbation technique. Expressions for skin-friction and heat transfer rate are also derived. The effects of the material parameters on velocity, temperature, skin-friction, and rate of heat transfer are discussed quantitatively.

scholarly journals Free Convection Phenomena in a Ribbed Wall

1990 ◽  
Author(s):  
N. S. Maravegias ◽  
D. P. Georgiou ◽  
D. D. Papailiou
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Thermal Field ◽  
Experimental Information ◽  
Convection Flow ◽  
Heated Plate ◽  
Transfer Enhancement ◽  
Free Convection Flow ◽  
Distance Ratio ◽  
Transfer Rates

The present study reports on experimental information regarding the turbulent free convection flow and thermal field structure, along an isothermally heated vertical flat plate with ribs. The hight to distance ratio of the ribs was equal to 0.1. The obtained experimental data consist of visualization of the flow, as well as detailed mean temperature and turbulent intensity distribution measurements covering the ribbed part of the heated plate. Heat transfer rates and their enhancement, due to the presence of the ribs, have been estimated from the obtained temperature profiles and by using Newton’s cooling law. Comparisons with corresponding measurements in forced convection reported in the literature, are also made. The described experiments constitute a first approach towards a more detailed investigation regarding the significant free convection currents existing under certain conditions in cooled channels. However, they also reveal some physical aspects of the heat transfer enhancement processes in ribbed surfaces which are believed to be applicable in more general situations and could lead to establishing some design criteria for ribbed surfaces.

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