Liquid Film Heat-Transfer Coefficients in a Vertical-Tube Forced-Circulation Evaporator

1934 ◽  
Vol 26 (10) ◽  
pp. 1044-1047 ◽  
Author(s):  
L. A. Logan ◽  
N. Fragen ◽  
W. L. Badger
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Vertical Tube ◽  
Transfer Coefficients ◽  
Forced Circulation ◽  
Heat Transfer Coefficients ◽  
Film Heat Transfer ◽  
Circulation Evaporator

Liquid-Film Heat Transfer Coefficients

1937 ◽  
Vol 29 (8) ◽  
pp. 905-910 ◽  
Author(s):  
Donald S. Ullock ◽  
W. L. Badger
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Film Heat Transfer

The Effect of Liquid Film Evaporation on Flow Boiling Heat Transfer in a Micro Tube

2010 ◽  
Author(s):  
Youngbae Han ◽  
Naoki Shikazono ◽  
Nobuhide Kasagi
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Liquid Film ◽  
Flow Boiling ◽  
Liquid Film Thickness ◽  
Periodic Pattern ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Micro Channels ◽  
Measured Liquid

Flow boiling in micro channels is attracting large attention since it leads to large heat transfer area per unit volume. Generated vapor bubbles in micro channels are elongated due to the restriction of channel wall, and thus slug flow becomes one of the main flow regimes. In slug flow, sequential bubbles are confined by the liquid slugs, and thin liquid film is formed between tube wall and bubble. Liquid film evaporation is one of the main heat transfer mechanisms in micro channels and liquid film thickness is a very important parameter to determine heat transfer coefficient. In the present study, liquid film thickness is measured under flow boiling condition and compared with the correlation proposed under adiabatic condition. The relationship between liquid film thickness and heat transfer coefficient is also investigated. Pyrex glass tube with inner diameter of D = 0.5 mm is used as a test tube. Working fluids are water and ethanol. Laser focus displacement meter is used to measure the liquid film thickness. Initial liquid film thickness under flow boiling condition can be predicted well by the correlation proposed under adiabatic condition. However, measured liquid film thickness becomes thinner than the predicted values in the cases of back flow and short slugs. These are considered to be due to the change of velocity profile in the liquid slug. Under flow boiling condition, liquid film profile fluctuates due to high vapor velocity and shows periodic pattern against time. Frequency of periodic pattern increases with heat flux. At low quality, heat transfer coefficients calculated from measured liquid film thickness show good accordance with heat transfer coefficients obtained directly from wall temperature measurements.

1987 Max Jakob Memorial Award Lecture: Dynamics and Stability of Thin Heated Liquid Films

1990 ◽  
Vol 112 (3) ◽  
pp. 538-546 ◽  
Author(s):  
S. G. Bankoff
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Heated Surface ◽  
Nucleate Boiling ◽  
Liquid Films ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Molecular Forces ◽  
Memorial Award ◽  
Film Heat Transfer

This review covers the dynamics and tendency toward rupture of thin evaporating liquid films on a heated surface. Very large heat transfer coefficients can be obtained. The applications include various boiling heat transfer and film cooling devices. A relatively new area for study is heat transfer through ultrathin films, which are less than 100 nm in thickness, and hence subject to van der Waals and other long-range molecular forces. Some recent work employing lubrication theory to obtain an evolution equation for the growth of a surface wave is described. Earlier phenomenological work is briefly discussed, as well as the connection between forced-convection subcooled nucleate boiling and thin-film heat transfer.

scholarly journals Measurement of Heat Transfer Coefficients in an Agitated Vessel with Tube Baffles

10.14311/1171 ◽  
2010 ◽  
Vol 50 (2) ◽  
Author(s):  
M. Dostál ◽  
K. Petera ◽  
F. Rieger
Keyword(s):  
Heat Transfer ◽  
Cold Water ◽  
Vertical Tube ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Steady State Method ◽  
Classic Approach ◽  
Large Heat ◽  
Common Operation ◽  
The Heat Transfer Coefficient

Cooling or heating an agitated liquid is a very common operation in many industrial processes. A classic approach is to transfer the necessary heat through the vessel jacket. Another option, frequently used in the chemical and biochemical industries is to use the heat transfer area of vertical tube baffles. In large equipment, e.g. fermentor, the jacket surface is often not sufficient for large heat transfer requirements and tube baffles can help in such cases. It is then important to know the values of the heat transfer coefficients between the baffles and the agitated liquid. This paper presents the results of heat transfer measurements using the transient method when the agitated liquid is periodically heated and cooled by hot and cold water running through tube baffles. Solving the unsteady enthalpy balance, it is possible to determine the heat transfer coefficient. Our results are summarized by the Nusselt number correlations, which describe the dependency on the Reynolds number, and they are compared with other measurements obtained by a steady-state method.

Heat Transfer in Rotating Serpentine Passages With Smooth Walls

1991 ◽  
Vol 113 (3) ◽  
pp. 321-330 ◽  
Author(s):  
J. H. Wagner ◽  
B. V. Johnson ◽  
F. C. Kopper
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Large Scale ◽  
Flow Direction ◽  
Vertical Tube ◽  
Operating Conditions ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Flow Equations ◽  
Heat Transfer Coefficients

Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large-scale, multipass, smooth-wall heat transfer model with both radially inward and outward flow. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature ratio, Rossby number, Reynolds number, and radius-to-passage hydraulic diameter ratio. These four parameters were varied over ranges that are typical of advanced gas turbine engine operating conditions. It was found that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs and that the effect of rotation on the heat transfer coefficients was markedly different depending on the flow direction. Local heat transfer coefficients were found to decrease by as much as 60 percent and increase by 250 percent from no-rotation levels. Comparisons with a pioneering stationary vertical tube buoyancy experiment showed reasonably good agreement. Correlation of the data is achieved employing dimensionless parameters derived from the governing flow equations.

Modeling of Wellbore Overall Heat Transfer in Circulation

2012 ◽  
Vol 260-261 ◽  
pp. 537-542
Author(s):  
Hui Fang Song ◽  
Rui He Wang ◽  
Hong Jian Ni
Keyword(s):  
Heat Transfer ◽  
Finite Element Analysis ◽  
Steady State ◽  
Radial Direction ◽  
Transfer Coefficients ◽  
Element Analysis ◽  
Heat Transfer Coefficients ◽  
Temperature Calculation ◽  
Wellbore Pressure ◽  
Film Heat Transfer

Heat is transferred between the fluid and the surroundings in the wellbore. Quantitative knowledge of wellbore heat transfer is important in drilling and production operations. A new model of wellbore heat transfer using finite element analysis is developed in this study. This solution assumes the heat transfer in the wellbore is steady state and only happens in radial direction. The model considers heat gained due to wellbore pressure loss in circulation, which is more accurate in temperature calculation. The overall heat resistance in the wellbore is analyzed, taking into account the film heat transfer coefficients difference between the tube and the annulus. Previous literature has been reviewed to determine the correlation which can be used in the model.

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