Free Convection Through Vertical Plane Layers of Non-Newtonian Power Law Fluids

1971 ◽  
Vol 93 (2) ◽  
pp. 164-171 ◽  
Author(s):  
A. F. Emery ◽  
H. W. Chi ◽  
J. D. Dale
Keyword(s):  
Free Convection ◽  
Vertical Plane ◽  
Constant Heat Flux ◽  
Experimental Measurements ◽  
Temperature Profiles ◽  
Flat Plates ◽  
Constant Heat ◽  
Layer Height ◽  
Power Law Fluids ◽  
Prandtl Numbers

Experimental measurements of the heat transferred from a constant heat flux hot wall across vertical plane layers of several pseudoplastic non-Newtonian fluids with generalized Prandtl numbers of 10–500 are reported for a range of Grashof moduli and layer height to width ratios. The rheological properties of the fluids are discussed and it is shown that the similarity analysis of free convection for constant-temperature vertical flat plates presented by Acrivos for infinite Prandtl numbers can be used to correlate the data. Several temperature profiles are given and compared to those measured in water.

Free Convection Through Vertical Plane Layers—Moderate and High Prandtl Number Fluids

1969 ◽  
Vol 91 (3) ◽  
pp. 391-401 ◽  
Author(s):  
R. K. MacGregor ◽  
A. F. Emery
Keyword(s):  
Free Convection ◽  
Vertical Plane ◽  
Constant Heat Flux ◽  
Variable Properties ◽  
Excellent Correlation ◽  
Wall Boundary Conditions ◽  
High Prandtl Number ◽  
Isothermal Wall ◽  
Prandtl Numbers ◽  
Rayleigh Numbers

The results of numerical computations are presented for free convection under isothermal wall and constant-heat-flux wall-boundary conditions. The effects of the Prandtl, Grashof, and Rayleigh numbers, aspect ratio, and variable properties are described. Experimental measurements of net heat transfer through vertical plane layers and of velocity and temperature profiles are given for Prandtl numbers of 1 to 20,000. A comparison of the laminar data with the numerical results shows excellent correlation.

Free convection from a constant heat flux elliptic tube

2003 ◽  
Vol 44 (15) ◽  
pp. 2445-2453 ◽  
Author(s):  
Amr O Elsayed ◽  
Emad Z Ibrahim ◽  
Sayed A Elsayed
Keyword(s):  
Heat Flux ◽  
Free Convection ◽  
Constant Heat Flux ◽  
Constant Heat

scholarly journals EFFECT OF CAVITY RATIO ON HEAT TRANSFER BY FREE LOAD FROM HEATED PLATES UPWARD WITH CONSTANT HEAT FLUX

2021 ◽  
Vol 9 (12) ◽  
pp. 686-695
Author(s):  
Waleed Abdulhadiethbayah ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Free Convection ◽  
Electronic Devices ◽  
Experimental Studies ◽  
Constant Heat Flux ◽  
Rate Of Change ◽  
Constant Heat ◽  
The Difference

Many engineering and industrial applications always seek to find ways to dissipate heat from heated surfaces used in these industries. As it is involved in the cooling of electronic parts and electrical transformers, as well as the design of solar collectors, in addition to being a process of heat exchange between hot surfaces and the fluids in contact with them. Since most electronic devices or their parts are cooled by removing the heat generated inside them by using air as a heat transfer medium and in a free convection way, and the fact that heat transfer by free convection occurs in many fields, so there were many studies that dealt with this topic. The free load is generated by the buoyant force (Bouncy force) As a result of the difference in the density of the fluid adjacent to the heated surface due to the difference in temperatures between the fluid and the surface. The laminar flow along surfaces has been extensively studied analytically [1,2,3,4] In the horizontal, inclined and vertical case, whether by constant heat flux or constant surface temperature, there are also many experimental studies of heat transfer by free convection from horizontal, inclined and vertical surfaces with constant heat flux or constant surface temperature [5,6,7,8]. Some experimental studies have also been conducted on heat transfer by convection from heated surfaces in the form of a disk (ring)The outcome of these studies was to extract an exponential mathematical relationship between the average of Nusselt number and the Kirchhoff number or Rayleigh number and the following formula: (Nu=C(Ra) n It is one of the most suitable formulas for heat transfer by free convection from heated surfaces in all its forms and over a wide range of Rayleigh number . It is noted that not all of these studies dealt with the study of the effect of the cavity ratio on heat transfer by free convection from square-shaped surfaces, which is the form that is more applied in electronic devices. Therefore, the current research means studying the rate of change in the average of Nusselt number, which represents a function of the rate of change in the rate of heat transfer by convection, as well as studying the thermal gradient above the surface, and this was done through using three hollow surfaces in proportions (0.25,0.5,0.75) of the total area.

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