Comparison of the results of modeling convective heat transfer in turbulent flows with experimental data

2010 ◽  
Vol 83 (5) ◽  
pp. 967-976 ◽  
Author(s):  
A. I. Fomichev
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convective Heat Transfer ◽  
Turbulent Flows ◽  
Convective Heat ◽  
Comparison Of The Results

A Study of Three-Dimensional Mixed Convective Heat Transfer From Short Vertical Cylinders in a Horizontal Forced Flow

2000 ◽  
Author(s):  
David A. Scott ◽  
P. H. Oosthuizen
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Three Dimensional ◽  
Forced Flow ◽  
Low Velocity ◽  
Buoyancy Forces ◽  
The Mean ◽  
Mixed Convective Flow ◽  
Comparison Of The Results

Abstract Heat transfer from relatively short vertical isothermal cylinders in a horizontal forced fluid flow has been considered. The flow conditions are such that the buoyancy forces resulting from the temperature differences in the flow are in general significant despite of the presence of a horizontal forced flow of air, that is, mixed convective flow exists. Because the cylinders are short and the buoyancy forces act normal to the forced flow, three-dimensional flow exists. The experiments were performed in a low velocity, open jet wind tunnel. The study involved the experimental determination of the mean heat transfer coefficient and a comparison of the results with a previous numerical analysis. Mean heat transfer rates were determined using the ‘lumped capacity’ method. The mean Nusselt number has the Reynolds number, Grashof number and the height to diameter ratio of the cylinders as parameters. The results have been used to determine the conditions under which the flow departs from purely forced convection and enters the mixed convection regime, i.e., determining the conditions for which the buoyancy effects should be included in convective heat transfer calculations for short cylinders.

Study on Forced Convective Heat Transfer of FC-72 in Vertical Small Tubes

2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Yantao Li ◽  
Yulong Ji ◽  
Katsuya Fukuda ◽  
Qiusheng Liu
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convection Heat Transfer ◽  
Bulk Liquid ◽  
Transfer Coefficients ◽  
Forced Convective Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

Abstract This paper presents an experimental investigation of the forced convective heat transfer of FC-72 in vertical tubes at various velocities, inlet temperatures, and tube sizes. Exponentially escalating heat inputs were supplied to the small tubes with inner diameters of 1, 1.8, and 2.8 mm and effective heated lengths between 30.1 and 50.2 mm. The exponential periods of heat input range from 6.4 to 15.5 s. The experimental data suggest that the convective heat transfer coefficients increase with an increase in flow velocity and µ/µw (refers to the viscosity evaluated at the bulk liquid temperature over the liquid viscosity estimated at the tube inner surface temperature). When tube diameter and the ratio of effective heated length to inner diameter decrease, the convective heat transfer coefficients increase as well. The experimental data were nondimensionalized to explore the effect of Reynolds number (Re) on forced convection heat transfer coefficient. It was found that the Nusselt numbers (Nu) are influenced by the Re for d = 2.8 mm in the same pattern as the conventional correlations. However, the dependences of Nu on Re for d = 1 and 1.8 mm show different trends. It means that the conventional heat transfer correlations are inadequate to predict the forced convective heat transfer in minichannels. The experimental data for tubes with diameters of 1, 1.8, and 2.8 mm were well correlated separately. And, the data agree with the proposed correlations within ±15%.

Effect of a Pair of Horizontal Frame Members on the Convective Heat Transfer With Laminar and Turbulent Flow From a Recessed Window to a Room

2011 ◽  
Author(s):  
Patrick H. Oosthuizen ◽  
David Naylor
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Convective Heat Transfer ◽  
Turbulent Flows ◽  
Heat Transfer Rate ◽  
Convective Heat ◽  
Transfer Rate ◽  
Numerical Study ◽  
Wall Functions ◽  
Inner Surface

The horizontal frame members that often protrude from the inner surface of a window can significantly effect the convective heat transfer rate from this inner surface to the room. The purpose of the present numerical study was to determine how the size of a pair of horizontal frame members effect this heat transfer rate. The flow has been assumed to be steady and conditions under which laminar, transitional, and turbulent flows occur are considered. Fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces, this being dealt with using the Boussinesq approach. The governing equations have been solved using the FLUENT commercial CFD code. The k-epsilon turbulence model with standard wall functions and with buoyancy force effects fully accounted for has been used. The solution has the following parameters: the Rayleigh number, the Prandtl number, the dimensionless window recess depth, and the dimensionless width and depth of the frame members. Results have been obtained for a Prandtl number of 0.74.

A Review of Forced Convective Heat Transfer in Stationary and Rotating Annuli

1996 ◽  
Vol 210 (2) ◽  
pp. 123-134 ◽  
Author(s):  
P R N Childs ◽  
C A Long
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Forced Convection ◽  
Turbulent Flows ◽  
Convective Heat ◽  
Heat Exchangers ◽  
Outer Cylinder ◽  
Forced Convective Heat Transfer ◽  
Analytical Research ◽  
Laminar And Turbulent Flows

The study of heat transfer by forced convection in annular passages is of interest across the range of process and aeronautical industries, for example from annular heat exchangers to the various configurations of annuli found in turbomachinery. The aim of this paper is to review relevant experimental, numerical and analytical research of heat transfer in both stationary and rotating annuli, with an emphasis on presenting useful information for designers. The geometries considered are the stationary annulus with superposed axial throughflow and the rotating annulus with rotation of either the inner or outer cylinder (both with and without throughflow). The work presented covers laminar and turbulent flows as well as flow regimes where transition occurs or vortex flows are present.

scholarly journals Numerical Investigation On The Impingement Of A Circular Jet Of Nanofluids On A Circular Flat Plate

2021 ◽  
Author(s):  
Dhimitri Kucuqi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convective Heat Transfer ◽  
Experimental Model ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

A numerical study was conducted to investigate and validate experimental convective heat transfer coefficient data associated with an Al2O3-H2O nanofluid through the use of an impingement jet on a flat, circular disk. It was observed that, in conjunction with experimental data, nanofluids provided increased local convective heat transfer coefficients in comparison to the base fluid. Nanofluid concentrations outlined in the experimental model, from 0.0198 to 0.0757 wt%, were investigated in a numerical model and resulting convective heat transfer coefficients were compared. In contrast to the experimental model, the maximum heat transfer enhancement occurred at the nanofluid concentration of 0.0757 wt%. In addition, several other models were tested with various Reynolds numbers and jet height-to-jet diameter ratios for further investigation along with discussion of sources of error. Overall, in comparison to experimental data, the lowest percentage errors achieved for the Reynolds numbers of 4245.7 and 8282 were 17.9% and 34.9%, respectively.

Supercritical Water Heat-Transfer Correlation for Vertical Bare Tubes

2009 ◽  
Author(s):  
Sarah Mokry ◽  
Yevgeniy Gospodinov ◽  
Igor Pioro ◽  
Pavel Kirillov
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Supercritical Water ◽  
Large Set ◽  
Heat Transfer Correlation ◽  
Experimental Dataset ◽  
Forced Convective Heat Transfer ◽  
Normal Heat

This paper presents an analysis of heat transfer to supercritical water in bare vertical tubes. A large set of experimental data, obtained in Russia, was analyzed and an updated heat-transfer correlation for supercritical water was developed. This experimental dataset was obtained within conditions similar to those for proposed SuperCritical Water-cooled nuclear Reactor (SCWR) concepts. Thus, the new correlation presented in this paper can be used for preliminary heat-transfer calculations in SCWR fuel channels. The experimental dataset was obtained for supercritical water flowing upward in a 4-m-long vertical bare tube. The data was collected at pressures of about 24 MPa for several combinations of wall and bulk-fluid temperatures that were below, at, or above the pseudocritical temperature. The values for mass flux ranged from 200–1500 kg/m2s, for heat flux up to 1250 kW/m2 and inlet temperatures from 320 to 350°C. Previous study (Pioro et al., 2008) confirmed that there are three heat-transfer regimes for forced convective heat transfer to water flowing inside tubes at supercritical pressures: (1) Normal heat-transfer regime; (2) Deteriorated heat-transfer regime, characterized by lower than expected heat transfer coefficients (HTCs) (i.e., higher than expected wall temperatures) than in the normal heat-transfer regime; and (3) Improved heat-transfer regime with higher-than-expected HTC values, and thus lower values of wall temperature within some part of a test section compared to those of the normal heat-transfer regime. The HTC data were compared to those values calculated with the Dittus-Boelter and Bishop et al. correlations. The comparison showed that the Bishop et al. correlation represents more closely HTC profiles along the heated length of the tube than the Dittus-Boelter correlation. The latter correlation deviates significantly from experimental data within the pseudocritical range. However, outside the pseudocritical region, the Dittus-Boelter correlation can predict closely experimental HTCs. It should be noted that neither of these correlations can be used for prediction of HTCs within the deteriorated heat-transfer regime. An updated heat-transfer correlation is presented in this paper for forced convective heat transfer in the normal heat-transfer regime to supercritical water in a bare vertical tube. It has demonstrated a good fit (±25%) for the analyzed dataset. This correlation can be used for future comparisons with other independent datasets, with bundled data, for the verification of computer codes for SCWR core thermalhydraulics and for the verification of scaling parameters between water and modeling fluids.

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