Natural Convective Heat Transfer on an Unheated Vertical Plate Attached to an Upstream Isothermal Plate

1983 ◽  
Vol 105 (4) ◽  
pp. 759-766 ◽  
Author(s):  
K. Kishinami ◽  
N. Seki
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Thermal Radiation ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Plate Thickness ◽  
Thermal Conductivity Ratio ◽  
Governing Equations ◽  
Difference Form ◽  
The Common

A numerical and experimental investigation on natural convective heat transfer with the coupling of heat conduction and thermal radiation from a vertical unheated plate connected to an upstream isothermal plate is carried out. The governing equations for conduction in the unheated plate and for convection in the boundary layer are written in finite difference form and are analyzed numerically by using an iterative technique coupled through the common heat flux with thermal radiation. The numerical results are discussed after comparing with the experimental results of temperature and velocity profiles and heat transfer coefficient. The coupling effects of heat conduction in the unheated plate and thermal radiation from the surface on laminar natural convective heat transfer from the plate connected to an isothermal heated upstream plate is greatly influenced by the plate-fluid thermal conductivity ratio and plate thickness, and the radiation emissivity of the plate.

Effects of Axial Heat Conduction in the Wall on Convection in Microtubes

2003 ◽  
Author(s):  
Zhi-Xin Li ◽  
Wei Wang ◽  
Zeng-Yuan Guo
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Conduction ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Boundary Condition ◽  
Thermal Conductivity Ratio ◽  
Convective Boundary ◽  
Axial Heat ◽  
Axial Heat Conduction

Single-phase convective heat transfer in microtubes was numerically studied with consideration on the heat conduction in the tube wall. It indicates that the Nusselt numbers of the fully developed laminar convective heat transfer in microtubes with convective boundary condition outside the tube vary from 3.66 to 4.36, which represent the conventional results for isothermal and constant heat flux boundaries respectively. The Nusselt number depends on the parameters of thermal conductivity ratio (k*), diameter ratio (D*), and Biot number. One-dimensional thermal resistance model could underestimate the Nusselt number if the axial heat conduction in the wall can not be ignored. Discrepancies between the experimental results for the Nusselt number based on 1-D model and the standard values might be misunderstood as being caused by novel phenomena at microscales.

scholarly journals A numerical study of free convective heat transfer in a double-glazed window with a between-pane Venetian blind

2021 ◽  
Author(s):  
Tony Avedissian
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Heat Transfer Rate ◽  
Convective Heat ◽  
Transfer Rate ◽  
Numerical Study ◽  
Thermal Conductivity Ratio ◽  
Number Range ◽  
Free Convective Heat Transfer ◽  
Venetian Blind

The free convective heat transfer in a double-glazed window with a between-pane Venetian blind has been studied numerically. The model geometry consists of a two-dimensional vertical cavity with a set of internal slats, centred between the glazings. Approximately 700 computational fluid dynamic solutions were conducted, including a grid sensitivity study. A wide set of geometrical and thermo-physical conditions was considered. Blind width to cavity width ratios of 0.5, 0.65, 0.8, and 0.9 were studied, along with three slat angles, 0º (fully open, +/- 45º (partially open), and 75º (closed). The blind to fluid thermal conductivity ratio was set to 15 and 4600. Cavity aspects of 20, 40, and 60, were examined over a Rayleigh number range of 10 to 10⁵, with the Prandtl number equal to 0.71. The resulting convective heat transfer data are presented in terms of average Nusselt numbers. Depending on the specific window/blind geometry, the solutions indicate that the blind can either reduce or enhance the convective heat transfer rate across the glazings. The present study does not consider radiation effects in the numerical solution. Therefore, a post-processing algorithm is presented that incorporates the convective and radiative influences, in order to determine the overall heat transfer rate across the window/blind system.

scholarly journals Mixed Convective Heat Transfer for MHD Viscoelastic Fluid Flow over a Porous Wedge with Thermal Radiation

2014 ◽  
Vol 6 ◽  
pp. 735939 ◽  
Author(s):  
M. M. Rashidi ◽  
M. Ali ◽  
N. Freidoonimehr ◽  
B. Rostami ◽  
M. Anwar Hossain
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Differential Equations ◽  
Thermal Radiation ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Viscoelastic Fluid ◽  
Main Concern ◽  
Highly Nonlinear ◽  
Special Cases

The main concern of the present paper is to study the MHD mixed convective heat transfer for an incompressible, laminar, and electrically conducting viscoelastic fluid flow past a permeable wedge with thermal radiation via a semianalytical/numerical method, called Homotopy Analysis Method (HAM). The boundary-layer governing partial differential equations (PDEs) are transformed into highly nonlinear coupled ordinary differential equations (ODEs) consisting of the momentum and energy equations using similarity solution. The current HAM solution demonstrates very good agreement with previously published studies for some special cases. The effects of different physical flow parameters such as wedge angle (β), magnetic field ( M), viscoelastic ( k1), suction/injection ( fw), thermal radiation ( Nr), and Prandtl number (Pr) on the fluid velocity component ( f′( η)) and temperature distribution ( θ( η)) are illustrated graphically and discussed in detail.

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