Heat Transfer to Fully Developed Liquid Metal Flow in Tubes

1967 ◽  
Vol 89 (3) ◽  
pp. 272-273 ◽  
Author(s):  
A. F. Emery ◽  
D. A. Bailey
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Metal ◽  
Metal Flow ◽  
Transitional Flow ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Liquid Metal Flow ◽  
Constant Wall Heat Flux ◽  
Experimental Values

Heat transfer coefficients for fully developed liquid metal flow in a tube with a constant wall heat flux are given for laminar and transitional flow. These experimental values agree with the Graetz value of 4.36, and support the work of Petukhov and Yushin in contradiction to that of Johnson, Hartnett, and Clabaugh.

scholarly journals Operating temperatures of oil-lubricated medium-speed gears: Numerical models and experimental results

2003 ◽  
Vol 217 (2) ◽  
pp. 87-106 ◽  
Author(s):  
H Long ◽  
A A Lord ◽  
D T Gethin ◽  
B J Roylance
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Rotational Speed ◽  
High Speed ◽  
Applied Load ◽  
Frictional Heat ◽  
Transfer Coefficients ◽  
Gear Teeth ◽  
Heat Transfer Coefficients

This paper investigates the effects of gear geometry, rotational speed and applied load, as well as lubrication conditions on surface temperature of high-speed gear teeth. The analytical approach and procedure for estimating frictional heat flux and heat transfer coefficients of gear teeth in high-speed operational conditions was developed and accounts for the effect of oil mist as a cooling medium. Numerical simulations of tooth temperature based on finite element analysis were established to investigate temperature distributions and variations over a range of applied load and rotational speed, which compared well with experimental measurements. A sensitivity analysis of surface temperature to gear configuration, frictional heat flux, heat transfer coefficients, and oil and ambient temperatures was conducted and the major parameters influencing surface temperature were evaluated.

A New Experimental Technique for Measuring Surface Heat Transfer Coefficients Using Uncalibrated Liquid Crystals

1999 ◽  
Author(s):  
Wayne N. O. Turnbull ◽  
Patrick H. Oosthuizen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Experimental Technique ◽  
Surface Heat Flux ◽  
Local Heat ◽  
Surface Heat ◽  
Phase Delay ◽  
Transfer Coefficients ◽  
Periodic Surface ◽  
Heat Transfer Coefficients

Abstract A new experimental technique has been developed that permits the determination of local surface heat transfer coefficients on surfaces without requirement for calibration of the temperature-sensing device. The technique uses the phase delay that develops between the surface temperature response and an imposed periodic surface heat flux. This phase delay is dependent upon the thermophysical properties of the model, the heat flux driving frequency and the local heat transfer coefficient. It is not a function of magnitude of the local heat flux. Since only phase differences are being measured there is no requirement to calibrate the temperature sensor, in this instance a thermochromic liquid crystal. Application of a periodic surface heat flux to a flat plate resulted in a surface colour response that was a function of time. This response was captured using a standard colour CCD camera and the phase delay angles were determined using Fourier analysis. Only the 8 bit G component of the captured RGB signal was required, there being no need to determine a Hue value. From these experimentally obtained phase delay angles it was possible to determine heat transfer coefficients that compared well with those predicted using a standard correlation.

Forced Convective Boiling of Refrigerant HCFC123 in a Mini-Tube

2010 ◽  
Author(s):  
Koichi Araga ◽  
Keisuke Okamoto ◽  
Keiji Murata
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flux ◽  
Pool Boiling ◽  
Constant Heat Flux ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Convective Boiling ◽  
Frictional Pressure Drop ◽  
Heat Transfer Coefficients

This paper presents an experimental investigation of the forced convective boiling of refrigerant HCFC123 in a mini-tube. The inner diameters of the test tubes, D, were 0.51 mm and 0.30 mm. First, two-phase frictional pressure drops were measured under adiabatic conditions and compared with the correlations for conventional tubes. The frictional pressure drop data were lower than the correlation for conventional tubes. However, the data were qualitatively in accord with those for conventional tubes and were correlated in the form φL2−1/Xtt. Next, heat transfer coefficients were measured under the conditions of constant heat flux and compared with those for conventional tubes and for pool boiling. The heat transfer characteristics for mini-tubes were different from those for conventional tubes and quite complicated. The heat transfer coefficients for D = 0.51 mm increased with heat flux but were almost independent of mass flux. Although the heat transfer coefficients were higher than those for a conventional tube with D = 10.3 mm and for pool boiling in the low quality region, they decreased gradually with increasing quality. The heat transfer coefficients for D = 0.30 mm were higher than those for D = 0.51 mm and were almost independent of both mass flux and heat flux.

Single-Phase and Boiling Cooling of Small Pin Fin Arrays by Multiple Nozzle Jet Impingement

1996 ◽  
Vol 118 (1) ◽  
pp. 21-26 ◽  
Author(s):  
David Copeland
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Single Phase ◽  
Jet Impingement ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Heat Transfer Coefficients ◽  
Aspect Ratios ◽  
Pin Fin Arrays

Experimental measurements of multiple nozzle submerged jet array impingement single-phase and boiling heat transfer were made using FC-72 and 1 cm square copper pin fin arrays, having equal width and spacing of 0.1 and 0.2 mm, with aspect ratios from 1 to 5. Arrays of 25 and 100 nozzles were used, with diameters of 0.25 to 1.0 mm providing nozzle area from 5 to 20 mm2 (5 to 20% of the heat source base area). Flow rates of 2.5 to 10 cm3/s (0.15 to 0.6 l/min) were studied, with nozzle velocities from 0.125 to 2 m/s. Single nozzles and smooth surfaces were also evaluated for comparison. Single-phase heat transfer coefficients (based on planform area) from 2.4 to 49.3 kW/m2 K were measured, while critical heat flux varied from 45 to 395 W/cm2. Correlations of the single-phase heat transfer coefficient and critical heat flux as functions of pin fin dimensions, number of nozzles, nozzle area and liquid flow rate are provided.

scholarly journals Experimental Heat Transfer Investigation of Stationary and Orthogonally Rotating Asymmetric and Symmetric Heated Smooth and Turbulated Channels

1992 ◽  
Author(s):  
H. A. El-Husayni ◽  
M. E. Taslim ◽  
D. M. Kercher
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Rotation Number ◽  
Symmetric Case ◽  
Wall Heat Flux ◽  
Heated Wall ◽  
Wall Heat Transfer ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Smooth Channel

An experimental investigation was conducted to determine the effects of variations in wall thermal boundary conditions on local heat transfer coefficients in stationary and orthogonally rotating smooth wall and two opposite-wall turbulated square channels. Results were obtained for three distributions of uniform wall heat flux: asymmetric, applied to the primary wall only; symmetric, applied to two opposite walls only; and fully-symmetric, applied to all four channel walls. Measured stationary and rotating smooth channel average heat transfer coefficients at channel location L/Dh = 9.53 were not significantly sensitive to wall heat flux distributions. Trailing side heat transfer generally increased with Rotation number whereas the leading wall results showed a decreasing trend at low Rotation numbers to a minimum and then an increasing trend with further increase in Rotation number. The stationary turbulated wall heat transfer coefficients did not vary markedly with the variations in wall heat flux distributions. Rotating leading wall heat transfer decreased with Rotation number and showed little sensitivity to heat flux distributions except for the fully-symmetric heated wall case at the highest Reynolds number tested. Trailing wall heat transfer coefficients were sensitive to the thermal wall distributions generally at all Reynolds numbers tested and particularly with increasing Rotation number. While the asymmetric case showed a slight deficit in trailing wall heat transfer coefficients due to rotation, the symmetric case indicated little change whereas the fully-symmetric case exhibited an enhancement.

Heat Removal and Thermal Stabilization of High-temperature Surfaces by a Dispersed Coolant Flow

Vestnik MEI ◽  
2021 ◽  
pp. 19-26
Author(s):  
Valentin S. Shteling ◽  
◽  
Vladimir V. Ilyin ◽  
Aleksandr T. Komov ◽  
Petr P. Shcherbakov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flux Density ◽  
Flow Rate ◽  
Heat Flux Density ◽  
Coolant Flow ◽  
Transfer Coefficients ◽  
Stationary Heat ◽  
Heat Transfer Coefficients ◽  
Stationary Heat Transfer

The effectiveness of stabilizing the surface temperature by a dispersed coolant flow is experimentally studied on a bench simulating energy intensive elements of thermonuclear installations A test section in which the maximum heat flux density can be obtained when being subjected to high-frequency heating was developed, manufactured, and assembled. The test section was heated using a VCh-60AV HF generator with a frequency of not lower than 30 kHz. A hydraulic nozzle with a conical insert was used as the dispersing device. Techniques for carrying out an experiment on studying a stationary heat transfer regime and for calculating thermophysical quantities were developed. The experimental data were obtained in the stationary heat transfer regime with the following range of coolant operating parameters: water pressure equal to 0.38 MPa, water mass flow rate equal to 5.35 ml/s, and induction heating power equal to 6--19 kW. Based on the data obtained, the removed heat flux density and the heat transfer coefficients were calculated for each stationary heat transfer regime. The dependences of the heat transfer coefficient on the removed heat flux density and of the removed heat flux density on the temperature difference have been obtained. High values of heat transfer coefficients and heat flux density at a relatively low coolant flow rate were achieved in the experiments.

Investigation of Buoyancy Effects in Asymmetrically Heated Near-Critical Flows of Carbon Dioxide in Horizontal Microchannels Using Infrared Thermography

2021 ◽  
Author(s):  
Lindsey V. Randle ◽  
Brian M. Fronk
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Flux ◽  
Infrared Thermography ◽  
Test Section ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Parallel Microchannels

Abstract In this study, we use infrared thermography to calculate local heat transfer coefficients of top and bottom heated flows of near-critical carbon dioxide in an array of parallel microchannels. These data are used to evaluate the relative importance of buoyancy for different flow arrangements. A Joule heated thin wall made of Inconel 718 applies a uniform heat flux either above or below the horizontal flow. A Torlon PAI test section consists of three parallel microchannels with a hydraulic diameter of 923 μm. The reduced inlet temperature (TR = 1.006) and reduced pressure (PR = 1.03) are held constant. For each heater orientation, the mass flux (520 kgm−2s−2 ≤ G ≤ 800 kgm−2s−2) and heat flux (4.7 Wcm−2 ≤ q″ ≤ 11.1 Wcm−2) are varied. A 2D resistance network analysis method calculates the bulk temperatures and heat transfer coefficients. In this analysis, we divide the test section into approximately 250 segments along the stream-wise direction. We then calculate the bulk temperatures using the enthalpy from the upstream segment, the heat flux in a segment, and the pressure. To isolate the effect of buoyancy, we screen the data to omit conditions where flow acceleration may be important or where relaminarization may occur. In the developed region of the channel, there was a 10 to 15 percent reduction of the local heat transfer coefficients for the upward heating mode compared to downward heating with the same mass and heat fluxes. Thus buoyancy effects should be considered when developing correlations for these types of flow.

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