Turbulent heat transfer measurements of supercritical CO₂ in a horizontal tube at relatively low Reynolds numbers

2012 ◽  
pp. EEP62
Author(s):  
Katsuyoshi Tanimizu ◽  
Shaikha Al-Suwaidi ◽  
Reza Sadr
Keyword(s):  
Heat Transfer ◽  
Horizontal Tube ◽  
Reynolds Numbers ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Low Reynolds Numbers ◽  
Low Reynolds

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.

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.

Heat transfer and drag for transverse flow past bundles of finned tubes at low reynolds numbers

1978 ◽  
Vol 14 (10) ◽  
pp. 905-907
Author(s):  
A. S. Lyshevskii ◽  
V. G. Sokolov ◽  
V. M. Sychev ◽  
L. Ya. Shkret
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Transverse Flow ◽  
Low Reynolds Numbers ◽  
Finned Tubes ◽  
Flow Past ◽  
Low Reynolds

The study of temperature regimes of a pipe wall under turbulent regime and supercritical pressures

2020 ◽  
Vol 34 (19) ◽  
pp. 2050182
Author(s):  
J. P. Mammadova ◽  
A. P. Abdullaev ◽  
R. M. Rzayev ◽  
R. F. Kelbaliev ◽  
S. H. Mammadova ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Physical Properties ◽  
Wall Temperature ◽  
Reynolds Numbers ◽  
Anomalous Behavior ◽  
Supercritical Pressure ◽  
Engineering Practice ◽  
Turbulent Regime ◽  
Low Reynolds Numbers ◽  
Low Reynolds

The flow regimes of liquids encountered in engineering practice are mainly turbulent due to their structure, with which the features of such flows at supercritical pressure are considered in the work and some results are compared with similar ones obtained at low Reynolds numbers. Under these conditions, the physical properties of the fluid change sharply in the parietal layer and, depending on the values of the heat flux density and temperature, the area of sharp changes in physical properties can move along the flow cross section. Depending on the influence of these factors, the nature of the fluid flow can change, which affects the patterns of heat transfer and, accordingly, the nature of the distribution of wall temperature. In particular, conditions were identified for the appearance of a primary and secondary improved heat transfer regime. The possibility of the existence of an anomalous behavior of heat transfer during a turbulent flow of aromatic hydrocarbons was revealed, the nature of the distribution of the wall temperature along the length of the experimental tube is examined, and the influence of changes in the thermophysical properties of the substance on it is analyzed. The experimental data for water and toluene with a deteriorated heat transfer mode deviate from the calculated by [Formula: see text]25%. As is known, the flow regime of fluids in engineering practice is mainly turbulent in structure. Therefore, it is very important to study the characteristics of such flows at supercritical pressure and compare some results with similar results obtained at low Reynolds numbers.

Sign in / Sign up

Export Citation Format

Share Document