TWO NEW FREE-FLIGHT METHODS FOR OBTAINING CONVECTIVE-HEAT-TRANSFER DATA

1964 ◽  
Author(s):  
DALE COMPTON ◽  
GARY CHAPMAN
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Free Flight ◽  
Transfer Data

Free Convection Effects on Laminar Forced Convective Heat Transfer in a Horizontal Isothermal Tube

1982 ◽  
Vol 104 (1) ◽  
pp. 145-152 ◽  
Author(s):  
W. W. Yousef ◽  
J. D. Tarasuk
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Free Convection ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Temperature Difference ◽  
Reynolds Numbers ◽  
Transfer Data ◽  
Forced Convective Heat Transfer ◽  
Nusselt Numbers

The influence of free convection due to buoyancy on forced laminar flow of air in the entrance region of a horizontal isothermal tube was investigated. The Graetz numbers ranged form 2.5 to 110.0, the Reynolds numbers ranged from 120 to 1200, the Grashof numbers ranged from 0.8 × 104 to 8.7 × 104, and the ratio L/D was varied from 6 up to 46. The average Nusselt numbers based on the log-mean temperature difference, ranged from 2.0 to 25.9. The heat transfer data were correlated according to the influence of free convection which was found to have a significant effect at points close to the entrance to the tube.

Supercritical Water Heat Transfer in a Vertical Bare Tube

2008 ◽  
Author(s):  
Yevgeniy Gospodinov ◽  
Sarah Mokry ◽  
Pavel Kirillov ◽  
Igor Pioro
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Supercritical Water ◽  
Wall Temperature ◽  
Test Section ◽  
Bulk Fluid ◽  
Transfer Data ◽  
Normal Heat ◽  
Bare Tube

This paper presents selected results on heat transfer to supercritical water flowing upward in a 4-m-long vertical bare tube. Supercritical water heat-transfer data were obtained at pressures of about 24 MPa, mass fluxes of 200 – 1500 kg/m2s, heat fluxes up to 884 kW/m2 and inlet temperatures from 320 to 350°C for several combinations of wall and bulk-fluid temperatures that were below, at or above the pseudocritical temperature. In general, the experiments 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 characterized in general with heat transfer coefficients (HTCs) similar to those of subcritical convective heat transfer far from critical or pseudocritical regions, which are calculated according to the Dittus-Boelter type correlations; (2) deteriorated heat-transfer regime with lower values of the HTC and hence higher values of wall temperature within some part of a test section compared to those of the normal heat-transfer regime; and (3) improved heat-transfer regime with higher values of the HTC and hence lower values of wall temperature within some part of a test section compared to those of normal heat-transfer regime. These new heat-transfer data are applicable as a reference dataset for future comparison with supercritical-water bundle data and for a verification of scaling parameters between water and modeling fluids. Also, these HTC data were compared to those calculated with the original Dittus-Boelter and Bishop et al. correlations. The comparison showed that the Bishop et al. correlation, which uses the cross-section average Prandtl number, represents HTC profiles more correctly along the heated length of the tube than the Dittus-Boelter correlation. In general, the Bishop et al. correlation shows a good agreement with the experimental HTCs outside the pseudocritical region, however, overpredicts the experimental HTCs within the pseudocritical region. The Dittus-Boelter correlation can also predict the experimental HTCs outside the pseudocritical region, but deviates significantly from the experimental data within the pseudocritical region. It should be noted that both these correlations cannot be used for a prediction of HTCs within the deteriorated heat-transfer regime.

Convective Heat Transfer Near One-Dimensional and Two-Dimensional Wall Temperature Steps

2004 ◽  
Vol 126 (2) ◽  
pp. 202-210 ◽  
Author(s):  
Debjit Mukerji ◽  
John K. Eaton ◽  
Robert J. Moffat
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Wall Temperature ◽  
Two Dimensional ◽  
Temperature Step ◽  
Transfer Data ◽  
One Dimensional ◽  
The One

Steady-state experiments with one-dimensional and two-dimensional calorimeters were used to study the convective heat transfer near sharp steps in wall temperature in a turbulent boundary layer. Data acquired under low and high freestream turbulence conditions indicated that spanwise turbulent diffusion is not a significant heat transport mechanism for a two-dimensional temperature step. The one-dimensional calorimeter heat transfer data were predicted within ±5 percent using the STAN7 boundary layer code for situations with an abrupt wall temperature step. The conventional correlation with an unheated starting length correction, in contrast, greatly under-predicts the heat transfer for the same experimental cases. A new correlation was developed that is in good agreement with near and far-field semi-analytical solutions and predicts the calorimeter heat transfer data to within ±2 percent for temperature step boundary condition cases.

Heat-Transfer and Flow-Friction Characteristics of Skewed-Passage and Glass-Ceramic Heat-Transfer Surfaces

1965 ◽  
Vol 87 (1) ◽  
pp. 72-86 ◽  
Author(s):  
C. P. Howard
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Glass Ceramic ◽  
Compact Heat Exchanger ◽  
Friction Characteristics ◽  
Transfer Data ◽  
Flow Friction

Experimental results for convective heat-transfer and flow-friction characteristics of three skewed-passage and four glass-ceramic compact heat-exchanger surfaces are presented which should be of practical use, particularly in the design of gas-turbine regenerators. The heat-transfer data were obtained by the transient technique.

Utilizing Disk Shaped Thermistors to Experimentally Determine the Prandtl Number Dependence Ranging From Vapors to Liquids

2009 ◽  
Author(s):  
Chris J. Kobus
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Temperature Sensors ◽  
Temperature Sensitive ◽  
Heavy Oils ◽  
External Temperature ◽  
Transfer Data

The current research utilizes disk-shaped thermistors to indirectly measure the convective heat transfer coefficient in the case of natural convection. Thermistors are resistors which have a resistance that is extremely temperature sensitive, so that experiments can be run with exceptional resolution. Not only can the convective heat transfer be indirectly measured, but so can the surface temperature, without the need for external temperature sensors which can interfere with the phenomena itself. Utilizing these themistors, heat transfer data was taken utilizing a variety of fluids from gasses (Pr = 0.72) to heavy oils (Pr ∼ 1000). From the experimental data, it was shown that the classical Nusselt-Rayleigh type correlation does not accurately predict the Prandtl number dependence for this geometry, and a new dimensionless correlation is proposed.

Utilizing Disk Shaped Thermistors to Experimentally Determine the Prandtl Number Dependence Ranging From Vapors to Liquids

2006 ◽  
Author(s):  
Chris J. Kobus ◽  
Dan Wu ◽  
Laila Guessous
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Temperature Sensors ◽  
Temperature Sensitive ◽  
Heavy Oils ◽  
External Temperature ◽  
Transfer Data

The current research utilizes disk-shaped thermistors to indirectly measure the convective heat transfer coefficient in the case of natural convection. Thermistors are resistors which have a resistance that is extremely temperature sensitive, so that experiments can be run with exceptional resolution. Not only can the convective heat transfer be indirectly measured, but so can the surface temperature, without the need for external temperature sensors which can interfere with the phenomena itself. Utilizing these themistors, heat transfer data was taken utilizing a variety of fluids from gasses (Pr = 0.72) to heavy oils (Pr ~ 1000). From the experimental data, it was shown that the classical Nusselt-Rayleigh type correlation does not accurately predict the Prandtl number dependence for this geometry, and a new dimensionless correlation is proposed.

Subcooled-Boiling and Convective Heat Transfer for Heptane Flowing Inside an Annulus and Past a Coiled Wire: Part II—Correlation of Data

1986 ◽  
Vol 108 (4) ◽  
pp. 928-933 ◽  
Author(s):  
H. Mu¨ller-Steinhagen ◽  
N. Epstein ◽  
A. P. Watkinson
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Subcooled Boiling ◽  
Transfer Data ◽  
Satisfactory Accuracy ◽  
Flow Past

In Part I of this paper, the authors reported an extensive series of heat transfer data for subcooled boiling of heptane in turbulent flow in an annulus, and in laminar flow past a coiled wire. These data plus some new measurements for laminar flow in the annulus were compared to the predictions of some 12 correlations from the literature. The applicability of these correlations to the present data is determined and a combination of correlations proposed to predict heat transfer with satisfactory accuracy.

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