Steady State Modeling of a Rotating Heat Pipe With a Composite Wick Structure

Volume 3 ◽  
2004 ◽  
Author(s):  
T. A. Jankowski ◽  
J. A. Waynert ◽  
F. C. Prenger ◽  
A. Razani
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Working Fluid ◽  
Round Cross Section ◽  
State Heat ◽  
Pipe Model ◽  
Axis Of Rotation ◽  
Wick Structure ◽  
Steady State Heat

A steady state heat pipe model, capable of calculating temperature and pressure distributions in the working fluid of a rotating heat pipe, is described here. The model can predict the performance of rotating heat pipes with a round cross-section, containing an annular gap composite wick structure. In addition to straight heat pipes, with a longitudinal axis that may or may not coincide with the axis of rotation, the model also allows for simulation of bent heat pipes. Using this model, results are generated for a bent heat pipe proposed for use in cooling rotating machinery. For the bent heat pipe, the condenser and adiabatic sections coincide with the axis of rotation, while the evaporator consists of an off-axis eccentrically rotating component, and a bend that allows for portion of the evaporator to be nearly perpendicular to the axis of rotation. The presence of the composite wick allows for heat pipe operation in both the rotating and stationary operating modes. Model results for the stationary operating mode compare favorably to the steady state heat pipe analysis code HTPIPE [1]. These comparisons for the stationary operating limit are significant, since HTPIPE has been benchmarked against experimental heat pipe data for nearly 30 years. As the rotational speed is increased, the rotation induced forces are used to drive the liquid flow to the evaporator. At high rotation rates, the liquid recedes from the wick, and forms a thin layer against the inside wall of the heat pipe. The results show that when a stable liquid layer is formed against the wall of the pipe, the shear stress opposes the rotation induced forces acting on the liquid, and limits the magnitude of the pressure and temperature rises in the working fluid (from the values predicted using a hydrostatic approximation).

scholarly journals NASA Lewis steady-state heat pipe code users manual

1992 ◽  
Author(s):  
L.K. Tower ◽  
K.W. Baker ◽  
T.S. Marks
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
State Heat ◽  
Steady State Heat

Experimental Model to Optimize the Design of Cylindrical Heat Pipes for Solar Collector Application

2013 ◽  
Vol 393 ◽  
pp. 735-740
Author(s):  
Fairosidi Idrus ◽  
Nazri Mohamad ◽  
Ramlan Zailani ◽  
Wisnoe Wirachman ◽  
Mohd Zulkifly Abdullah
Keyword(s):  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Design Parameters ◽  
Working Fluid ◽  
Pipe Material ◽  
Efficient Design ◽  
Wick Structure ◽  
To Come ◽  
Transfer Device

A heat pipe is a heat-transfer device that use the principles of thermal conductivity and phase change to transfer heat between two ends at almost constant temperature. The thermal peformance of cylindrical heat pipes depends on design parameters such as dimensions of the heat pipe, material, wick structure and the working fluid. An experimental strategy was designed to study the effect of these parameters on the thermal performance of cylindrical heat pipes. The experimental design was conceived by employing the Taguchi method. The final aim of the experiments is to come up with design parameters that will yield optimum thermal performance. This paper presents an efficient design of experiment and the associated experimental setup and procedures to be carried out in order to optimize the design of cylindrical heat pipes.

The Effect of Working Fluid Inventory on the Performance of Revolving Helically Grooved Heat Pipes

2000 ◽  
Vol 123 (1) ◽  
pp. 120-129 ◽  
Author(s):  
R. Michael Castle ◽  
Scott K. Thomas ◽  
Kirk L. Yerkes
Keyword(s):  
Heat Pipe ◽  
Heat Pipes ◽  
Working Fluid ◽  
Maximum Heat ◽  
Limit Model ◽  
Filling Station ◽  
Capillary Limit ◽  
Helical Groove ◽  
Wick Structure ◽  
Evaporative Heat Transfer

The results of a recently completed experimental and analytical study showed that the capillary limit of a helically-grooved heat pipe (HGHP) was increased significantly when the transverse body force field was increased. This was due to the geometry of the helical groove wick structure. The objective of the present research was to experimentally determine the performance of revolving helically-grooved heat pipes when the working fluid inventory was varied. This report describes the measurement of the geometry of the heat pipe wick structure and the construction and testing of a heat pipe filling station. In addition, an extensive analysis of the uncertainty involved in the filling procedure and working fluid inventory has been outlined. Experimental measurements include the maximum heat transport, thermal resistance and evaporative heat transfer coefficient of the revolving helically grooved heat pipe for radial accelerations of |a⃗r|=0.0, 2.0, 4.0, 6.0, 8.0, and 10.0-g and working fluid fills of G=0.5, 1.0, and 1.5. An existing capillary limit model was updated and comparisons were made to the present experimental data.

A Titanium Based Flat Heat Pipe

2008 ◽  
Author(s):  
Changsong Ding ◽  
Gaurav Soni ◽  
Payam Bozorgi ◽  
Brian Piorek ◽  
Carl D. Meinhart ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Aspect Ratio ◽  
Heat Pipe ◽  
Carrying Capacity ◽  
High Aspect Ratio ◽  
Capillary Flow ◽  
Titanium Substrate ◽  
Heat Pipes ◽  
Working Fluid ◽  
Wick Structure

We are developing innovative heat pipes based on Nano-Structured Titania (NST) with a potential for high heat carrying capacity and high thermal conductivity. These heat pipes have a flat geometry as opposed to a cylindrical geometry found in conventional heat pipes. The flatness will enable a good contact with microprocessor chips and thus reduce the thermal contact resistance. We refer to it as a Thermal Ground Plane (TGP) because of its flat and thin geometry. It will provide the ability to cool the future generations of power intensive microprocessor chips and circuit boards in an efficient way. It also brings the potential to function in high temperature (>150°C) fields because of its high yield strength and compatibility [1]. The TGP is fabricated with Titanium. It adopts the recently developed high aspect ratio Ti processing techniques [2] and laser packaging techniques. The three main components of the TGP are 1) a fine wick structure based on arrays of high aspect ratio Ti pillars and hair like structures of Nano-Structured Titania (NST), 2) A shallow Ti cavity welded onto the wick structure and 3) the working fluid, water, sealed between the cavity and the wick. The heat carrying capacity and the thermal conductivity of a heat pipe are generally determined by the speed of capillary flow of the working fluid through its wick. The TGP wick has the potential to generate high flow rates and to meet the growing challenges faced by electronics cooling community. The TGP wick structure, developed by etching high aspect ratio pillars in a titanium substrate and growing nano scale hairs on the surface of the pillars, is super hydrophilic and capable of wicking water at velocities ∼ 10−2 m/s over distances of several centimeters. The thermal conductivity of the current TGP device was measured to be k = 350 W/m·K. The completed TGP device has the potential of attaining a higher conductivity by improving the wicking material and of carrying higher power density. Washburn equation [3] for dynamics of capillary flow has been employed to explain the results of our experiments. The experiment shows a good agreement with Washburn equation.

The Anti-Gravity Phenomena in EHD Heat Pipe Model

2002 ◽  
Author(s):  
Jiaxiang Yang ◽  
Jiancai Wang ◽  
Chuntian Chen ◽  
Changsheng Yu
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Copper Wire ◽  
Heat Pipes ◽  
Working Fluid ◽  
Dc Voltage ◽  
Pipe Model ◽  
Condensation Section ◽  
Insulating Liquid ◽  
Saturation Vapor

A heat pipe model of electrohydrodynamical (EHD) enhancement heat transfer has been designed and made. The insulating liquid was selected as working fluid and the copper wire whose diameter was 1mm was used as the high voltage electrode. The temperature in the inlet and outlet of both the vaporization section and the condensation section, the saturation vapor pressure inside this model were measured respectively under different applied dc voltage and different tilt angle, that is, the vaporization section was placed higher than the condensation section. The experiment results indicate that the circumfluence between the condensation section and the vaporization section was improved with the increase of the applied dc voltage. Such EHD enhancement heat transfer technology can be practically employed in the heat transfer engineering, and has some reference values for the investigation of heat pipes used in the case of anti-gravity.

Simple Conduction Model for Theoretical Steady-State Heat Pipe Performance

AIAA Journal ◽  
1972 ◽  
Vol 10 (8) ◽  
pp. 1051-1057 ◽  
Author(s):  
K. H. SUN ◽  
C. L. TIEN
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Conduction Model ◽  
State Heat ◽  
Steady State Heat

Investigation of Heat Pipe Drilling Application

2004 ◽  
Author(s):  
Tien-Chien Jen ◽  
Yau Min Chen ◽  
Fern Tuchowski
Keyword(s):  
Heat Pipe ◽  
Experimental Studies ◽  
Heat Pipes ◽  
Cutting Fluid ◽  
Working Fluid ◽  
Federal State ◽  
Hole Making ◽  
Wick Structure ◽  
The Operating Mechanism ◽  
State And Local

It’s widely known that hole making is, by a significant margin, the most frequently performed process among metalworking operations. It’s also among the most difficult operations to control from a thermal perspective. The most common cooling method is the use of cutting fluids flooding through the cutting zone. However, disposal of the used fluids is subject to federal, state and local laws and regulations. More stringent regulations in environmental pollution are expected in the future, we can expect the cost associated with coolants to continue to rise. Experimental studies implementing the use of a heat pipe to cool the drill and thus reduce the amount of cutting fluid required have been recently conducted. The heat pipe works with no moving parts or electronics and it also offers an effective alternative to removing heat without significant increases in operating temperatures. The operating mechanism of heat pipes have been extensively studied, however, rotating heat pipes with a wick structure has not received adequate attention in the past. In this study, a numerical analysis has been conducted to model the flow in an axially rotating heat pipe. The result shows the transport capacity is strongly affected by changes in the thermal physical properties of the working fluid with the temperature. The rotating speeds have strong effect in the vapor core but this effect is weak in the liquid flow of the wick structure.

Experimental Investigation of High-Speed Rotating Heat Pipes

2003 ◽  
Author(s):  
F. Song ◽  
D. Home ◽  
T. Robinson ◽  
D. Ewing ◽  
C. Y. Ching
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
High Speed ◽  
Heat Pipes ◽  
Theoretical Models ◽  
Test Facility ◽  
Working Fluid ◽  
Steady State Heat ◽  
Steady State Heat Transfer ◽  
Pipe Geometry

The steady state heat transfer characteristics of high-speed rotating heat pipes were measured using a newly commissioned high-speed rotating heat pipe test facility. The performance of two cylindrical and two tapered rotating heat pipes with different fluid loadings were tested for rotational speeds of 2,000 to 4,000 RPM and heat transfer rates up to 0.6 kW. The measurements were used to characterize the effects of rotational speed, working fluid loading, and heat pipe geometry on the performance of rotating heat pipes. The results were compared to previous theoretical models. There is a general agreement between test results and predictions from a model that accounts for natural convection within the liquid film at the evaporator at high accelerations. However, some results indicate that the model is not yet accounting for all the physics in a high-speed rotating heat pipe.

Sign in / Sign up

Export Citation Format

Share Document