Turbulent Heat Transfer at Low Reynolds Numbers

1969 ◽  
Vol 91 (4) ◽  
pp. 532-536 ◽  
Author(s):  
C. J. Lawn
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Eddy Diffusivity ◽  
Reynolds Numbers ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Low Reynolds Numbers ◽  
Eddy Diffusivities ◽  
Uniform Wall ◽  
Uniform Wall Heat Flux

A realistic velocity profile and semiempirical values for the ratio of the eddy diffusivities of momentum and heat are used to solve the heat-balance equation for the situation of fully developed gas flow in a pipe with uniform wall heat flux. The predicted heat transfer is higher than the experimental at Reynolds numbers below 104 and this is shown to be due to the inadequacy of the simple eddy-diffusivity hypothesis.

THE MOMENTUM AND VORTICITY TRANSFER THEORIES OF TURBULENT HEAT TRANSFER

1954 ◽  
Vol 32 (6) ◽  
pp. 419-429 ◽  
Author(s):  
A. W. Marris
Keyword(s):  
Heat Transfer ◽  
Outer Boundary ◽  
Eddy Diffusivity ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Distribution Law ◽  
Radial Temperature ◽  
Turbulent Region ◽  
Eddy Diffusivities ◽  
Developed Turbulence

The case of heat transfer by a cylindrical turbulent region is examined further theoretically from the standpoint of the vorticity transfer analogy. The radial distribution of the eddy diffusivity for vorticity is considered and, on the logarithmic velocity distribution law for fully developed turbulence, this quantity is found to be negative throughout an interval at the outer boundary of the turbulent region. When this region is excluded from the relevant integrals, results are obtained for the Nusselt modulus and radial temperature distribution for the particular case of Prandtl number equal to the ratio of the eddy diffusivities for vorticity and heat, and are compared with the corresponding results on the momentum transfer analogy theory.

scholarly journals Experimental Study of Heat Transfer Enhancement through a Tube with Wire-Coil Inserts at Low Turbulent Reynolds Number

2018 ◽  
Vol 3 (3) ◽  
pp. 122-133
Author(s):  
Mohammad Zoynal Abedin ◽  
M. A. Rashid Sarkar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Test Section ◽  
Reynolds Numbers ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Low Reynolds Numbers ◽  
Wire Coil ◽  
Low Reynolds

This paper reports an experimental analysis to investigate the enhancement of turbulent heat transfer flow of air through one smooth tube and four different tubes with wire-coil inserts (Pitches, Pc = 12, 24, 40, and 50 mm with corresponding helix angles, a =100, 200, 350, and 450, respectively) at low Reynolds numbers ranging from 6000 to 22000. The test section of the tube was electrically heated and was cooled by fully developed turbulent air flow. The performance of the tubes was evaluated by considering the condition of maximizing heat transfer rate. From the measured data, the heat transfer characteristics such as heat transfer coefficient, effectiveness and Nusselt number, and the fluid flow behaviours such as friction factor, pressure drops and pumping power along the axial distance of the test section were analyzed at those Reynolds numbers for the tubes. The results indicated that for the tubes with wire-coil inserts at low Reynolds numbers, the turbulent heat transfer coefficient might be as much as two-folds higher, the friction factors could be as much as four-folds higher, and the effectiveness might be as much as 1.25 folds higher than those for the smooth tube with similar flow conditions. A correlation was also developed to predict the turbulent heat transfer coefficients through the tubes at low Reynolds numbers.

A Surface Rejuvenation Model for Turbulent Heat Transfer in Annular Flow With High Prandtl Numbers

1978 ◽  
Vol 100 (1) ◽  
pp. 92-97 ◽  
Author(s):  
B. T. F. Chung ◽  
L. C. Thomas ◽  
Y. Pang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Annular Flow ◽  
Circular Tube ◽  
Eddy Diffusivity ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Fully Developed Flow ◽  
High Prandtl Number ◽  
Prandtl Numbers

Heat transfer for high Prandtl number fluids flowing turbulently in a concentric circular tube annulus with prescribed wall heat flux is investigated analytically. This surface rejuvenation based analysis is restricted to thermally and hydrodynamically fully developed flow with constant properties and negligible viscous dissipation. This formulation leads to predictions for the Nusselt Number that are in basic agreement with predictions obtained on the basis of earlier eddy diffusivity models for 30 ≤ Pr ≤ 1000 and 104 ≤ Re ≤ 106.

Predictions of Turbulent Heat Transfer in an Axisymmetric Jet Impinging on a Heated Pedestal

1999 ◽  
Vol 121 (1) ◽  
pp. 43-49 ◽  
Author(s):  
S. Parneix ◽  
M. Behnia ◽  
P. A. Durbin
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Turbulence Model ◽  
Reynolds Numbers ◽  
Turbulent Heat Transfer ◽  
Recent Experimental Data ◽  
Turbulent Heat ◽  
Normal Velocity ◽  
Comparison Results ◽  
The One

Cooling or heating of a flat plate by an impinging jet, due to its many applications, has been widely studied. Recent experimental data concerning more complex geometries has become available. In this study, the cooling of a heated pedestal mounted on a flat plate, a configuration which is closer to the one met in some engineering applications (e.g., cooling of electronic components), has been numerically simulated. The normal velocity relaxation turbulence model (V2F model) in an axisymmetric geometry has been adopted. Results have been obtained for a range of jet Reynolds numbers and jet-to-pedestal distances. Comparison of the predicted heat transfer coefficient with experiments has shown a very good agreement. For comparison, results have also been obtained with the widely used κ – ε turbulence model and the agreement with the data is poor.

Sign in / Sign up

Export Citation Format

Share Document