Variable-Property Turbulent Flow in a Horizontal Smooth Tube during Uniform Heating and Constant Surface-Temperature Cooling

1973 ◽  
Vol 95 (1) ◽  
pp. 134-135 ◽  
Author(s):  
J. Zucchetto ◽  
R. S. Thorsen
Keyword(s):  
Turbulent Flow ◽  
Surface Temperature ◽  
Smooth Tube ◽  
Uniform Heating ◽  
Variable Property

scholarly journals CFD and Experimental Analysis of a Falling Film outside Smooth and Helically Grooved Tubes

2014 ◽  
Vol 6 ◽  
pp. 915034 ◽  
Author(s):  
Cenk Onan ◽  
Derya Burcu Ozkan ◽  
Serkan Erdem
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Transfer Coefficient ◽  
Surface Temperature ◽  
Transfer Coefficient ◽  
Experimental Results ◽  
Smooth Tube ◽  
Falling Film ◽  
Grooved Tube

Simultaneous heat and mass transfer are investigated in a falling film outside grooved and smooth tubes. A numerical analysis of the helically trapezoidal-grooved and reference smooth tube was performed in the computational fluid dynamics program “Ansys Fluent 14.” The three-dimensional model drawings in the x, y, and z coordinates are used, and the effects of the falling film outside the helically grooved tube on the surface temperature and surface heat transfer coefficient are determined. The average surface temperature, heat transfer coefficient, and Nu values are determined experimentally for a constant heat flux. An uncertainty analysis and Nu correlation for the grooved tube are also provided in this study. The Reynolds number varied between 50 and 350 for the falling film and between 1500 and 3500 for air. Using a computational fluid dynamics (CFD) analysis for the reference smooth tube, the experimental results are validated within 2–12% difference. The experimental results are also within 6–13% of the grooved tubes.

Molecular diffusion in the laminar sub-layer during turbulent flow in a smooth tube

2004 ◽  
Vol 59 (6) ◽  
pp. 1191-1197 ◽  
Author(s):  
C.R. Huang ◽  
A.F. Denny ◽  
N.W. Loney
Keyword(s):  
Turbulent Flow ◽  
Molecular Diffusion ◽  
Smooth Tube

Subcooled Boiling Heat Transfer for Turbulent Flow of Water in a Short Vertical Tube

2008 ◽  
Author(s):  
Koichi Hata ◽  
Nobuaki Noda
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Surface Temperature ◽  
Boiling Heat Transfer ◽  
Vertical Tube ◽  
Test Tube ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Average Roughness ◽  
Inner Surface

The subcooled boiling heat transfer for Platinum test tube divided into three sections (upper, mid and lower positions) for the flow velocities (u = 4.0 to 13.3 m/s), the inlet liquid temperatures (Tin = 295.26 to 305.25 K), the inlet pressures (Pin = 739.26 to 1064.48 kPa) and the exponentially increasing heat input with various periods (Q = Q0 exp(t/τ), τ = 22.52 ms to 26.31 s) was systematically measured by an experimental water loop comprised of a pressurizer. The Platinum test tube of inner diameter (d = 3 mm), heated length (L = 66.5 mm), L/d (= 22.17) and wall thickness (δ = 0.5 mm) with a commercial finish of inner surface (average roughness, Ra = 0.40 μm) is used in this work. The outer surface temperature of the test tube was observed by an infrared thermal imaging camera. The axial variations of the inner surface temperature, the heat flux and the heat transfer coefficient from non-boiling to CHF were clarified. The subcooled boiling heat transfer for Platinum test tube with a commercial finish of inner surface was compared with the values calculated by other workers’ correlations for the subcooled boiling heat transfer. The influence of exponential period (τ) and flow velocity (u) on the subcooled boiling heat transfer is investigated into details and the predictable correlation of the subcooled boiling heat transfer for turbulent flow of water in a short vertical tube is derived based on the experimental data for Platinum test tube with a commercial finish of inner surface. The correlation can describe the subcooled boiling heat transfer coefficients obtained in this work within 15% difference.

Computational simulations of buoyancy-influenced turbulent flow and heat transfer in a vertical plane passage

2004 ◽  
Vol 218 (11) ◽  
pp. 1385-1397 ◽  
Author(s):  
J Wang ◽  
J Li ◽  
S He ◽  
J D Jackson
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Turbulent Flow ◽  
Computational Study ◽  
Convective Heat Transfer Coefficient ◽  
Vertical Plane ◽  
Heated Wall ◽  
Computational Simulations ◽  
Variable Property ◽  
Flow And Heat Transfer

Computational simulations are reported of some recent experiments on turbulent variable-property mixed convection to air flowing upwards and downwards through a vertical plane passage, one wall of which was uniformly heated. In addition to heat transfer from that wall by convection, there was some radiative heat transfer to the opposite wall. In the experimental study, measurements were made of profiles of velocity and turbulence within the flow, and also local values of convective heat transfer coefficient were determined along the heated wall. The Reynolds number was varied from 44000 down to 7000 and the Grashof number from 3.0 × 108 to 9.0 × 09. To simulate the experiments by computational means, the governing equations for variable-property buoyancy-influenced two-dimensional turbulent flow and heat transfer in Reynolds-averaged form were solved using an elliptic formulation in conjunction with two well-known low-Reynolds-number k-e turbulence models. In this paper, results from the computational study are compared directly with experiment. In general, the observed effects of buoyancy on flow and heat transfer were satisfactorily reproduced but there were some clear discrepancies between the predictions and the experimental results, especially with downward flow under conditions where the influence of buoyancy was strong.

An Indirect Method of Investigating Heat Transfer in Turbulent Flow in a Tube

1986 ◽  
Vol 10 (1) ◽  
pp. 1-7 ◽  
Author(s):  
B.S. Larkin ◽  
P. Savic
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Surface Temperature ◽  
Indirect Method ◽  
Liquid Interfaces ◽  
Tube Surface ◽  
Measure Surface Temperature ◽  
Surface Liquid

This paper describes a method of determining the correlation for heat transfer in turbulent flow in a tube, by measuring the heat transfer between water flowing through two similar tubes soldered together. This technique eliminates the need to measure surface temperature and minimizes thermocouple errors. Excellent consistency is obtained and it is argued that this implies accuracy of the same order. An analysis is given which describes the conduction of heat between the two tube surface/liquid interfaces.

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