Determination of representative and instantaneous process side heat transfer coefficients in agitated vessel using heat flux sensors

2005 ◽  
Vol 44 (9) ◽  
pp. 993-998 ◽  
Author(s):  
G. Delaplace ◽  
J.-F. Demeyre ◽  
R. Guérin ◽  
P. Debreyne ◽  
J.-C. Leuliet
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Transfer Coefficients ◽  
Agitated Vessel ◽  
Heat Transfer Coefficients ◽  
Heat Flux Sensors

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.

Determination of heat transfer coefficients for complex spray cooling arrangements

2016 ◽  
Vol 11 (3/4) ◽  
pp. 229 ◽  
Author(s):  
Sebastian Herbst ◽  
Kim Florian Steinke ◽  
Hans Jürgen Maier ◽  
Andrzej Milenin ◽  
Florian Nürnberger
Keyword(s):  
Heat Transfer ◽  
Spray Cooling ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

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.

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