scholarly journals Analysis of a Vertical Flat Heat Pipe Using Potassium Working Fluid and a Wick of Compressed Nickel Foam

Energies ◽  
2016 ◽  
Vol 9 (3) ◽  
pp. 170 ◽  
Author(s):  
Geir Hansen ◽  
Erling Næss ◽  
Kolbeinn Kristjansson
Keyword(s):  
Heat Pipe ◽  
Nickel Foam ◽  
Working Fluid ◽  
Flat Heat Pipe

Passivation and Performance of Inorganic Aqueous Solutions in a Grooved Aluminum Flat Heat Pipe

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Michael J. Stubblebine ◽  
Ivan Catton
Keyword(s):  
Aqueous Solutions ◽  
Heat Pipe ◽  
Operating Performance ◽  
Heat Pipes ◽  
Hydrogen Gas ◽  
Working Fluid ◽  
Heating Section ◽  
And Performance ◽  
Aluminum Plates ◽  
Flat Heat Pipe

Aluminum heat pipes have traditionally been incompatible with water and water-based fluids because they quickly react to generate noncondensable hydrogen gas (NCG). Two different inorganic aqueous solutions (IAS) are tested in a flat heat pipe (FHP). Grooved aluminum plates were used as the heat pipe wick and the tests were run with the heating section raised above the condenser. Compatibility between the working fluid and the aluminum heat pipe was established by running the device to dryout and observing thermal resistance results along the way. De-ionized (DI) water was also tested, as a baseline for comparison, to establish that it did indeed fail as expected. Operating performance of each mixture was obtained from zero heat input until dryout was reached for two angles of inclination. The data suggest that both IAS mixtures are compatible with aluminum heat pipes and exhibit performance similar to that of a copper and water heat pipe. It is demonstrated that IAS and aluminum heat pipes show potential for replacing existing copper and water devices for some applications and provide alternative options for heat pipe designers who value both the thermophysical property advantages of water and reduced weight of aluminum devices.

Investigation of a Novel Flat Heat Pipe

2005 ◽  
Vol 127 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Yaxiong Wang ◽  
G. P. Peterson
Keyword(s):  
Heat Pipe ◽  
Heat Transport ◽  
Thermal Design ◽  
Experimental Results ◽  
Design Parameters ◽  
Working Fluid ◽  
Transport Capacity ◽  
Maximum Heat ◽  
Mesh Screen ◽  
Flat Heat Pipe

A novel flat heat pipe has been developed to assist in meeting the high thermal design requirements in high power microelectronics, power converting systems, laptop computers and spacecraft thermal control systems. Two different prototypes, each measuring 152.4 mm by 25.4 mm were constructed and evaluated experimentally. Sintered copper screen mesh was used as the primary wicking structure, in conjunction with a series of parallel wires, which formed liquid arteries. Water was selected as the working fluid. Both experimental and analytical investigations were conducted to examine the maximum heat transport capacity and optimize the design parameters of this particular design. The experimental results indicated that the maximum heat transport capacity and heat flux for Prototype 1, which utilized four layers of 100 mesh screen were 112 W and 17.4W/cm2, respectively, in the horizontal position. For Prototype 2, which utilized six layers of 150 mesh screen, these values were 123 W and 19.1W/cm2, respectively. The experimental results were in good agreement with the theoretical predictions for a mesh compact coefficient of C=1.15.

Experimental Study of an Airfoil Heat Pipe Subjected to an Impingement of Hot Gases

2012 ◽  
Author(s):  
Gerardo Carbajal ◽  
Alberto Vázquez Ramos
Keyword(s):  
Experimental Study ◽  
Heat Pipe ◽  
Heat Input ◽  
Nickel Foam ◽  
Average Pore Size ◽  
Leading Edge ◽  
Jet Impingement ◽  
Experimental Result ◽  
Working Fluid ◽  
Average Pore

An experimental study was performed to an airfoil heat pipe. The airfoil was subjected to a jet impingement of hot gases at the leading edge. The airfoil was also tested first with air and later with water as the working fluid. The experimental result shown that the heat pipe spread better the heat input from the leading edge at very high heat input rate than the air filled airfoil design. The case material was brass, the porous media was nickel foam with 1.70 mm thickness and average pore size of 590 × 10−6 m. Distilled water was used as the working fluid. The experimental data indicate the proposed design can reduce the temperature at the leading edge surface. The temperature reduction in the leading edge airfoil heat pipe was approximately 33 percent compared with the air filled airfoil. The phase change mechanism inside the heat pipe was the key factor to spread better the localized energy input and thus reducing the temperature distribution on the leading edge.

Transient Thermal and Hydrodynamic Performances of Flat Heat Pipe Subjected to Heating With Multiple Electronic Components

2008 ◽  
Author(s):  
R. Sonan ◽  
S. Harmand ◽  
J. Pelle´ ◽  
D. Leger ◽  
M. Fake`s
Keyword(s):  
Heat Pipe ◽  
Heat Removal ◽  
Copper Plate ◽  
Working Fluid ◽  
Governing Equations ◽  
Electronic Components ◽  
Pressure Distributions ◽  
Change Mechanisms ◽  
Transient Thermal ◽  
Flat Heat Pipe

This work is aimed to simulate the transient performances of a flat heat pipe (FHP) used to cool electronics components in automotive applications. A transient 3D thermal model (T3DTM) of the FHP wall is performed to calculate the heat transfer through the wall of the FHP. This model is coupled with a transient 2D hydrodynamic model (T2DHM) which determines the flows both in wick and vapour core. An energy balance and Clausius-Clapeyron law permit to represent the phase change mechanisms at the liquid-vapour interface. The performed T2DHM model includes the solution of the complete governing equations in both wick and vapor core. The T2DHM is able to predict the velocity and pressure distributions of the FHP working fluid and then the FHP transient response. That analysis helps determine the maximum pore radius of the wick necessary to support the total pressure drop in the FHP. The heat removal capability of the FHP is highlighted through a comparison with a solid copper plate of the overall dimensions as the FHP.

Development of a Passive Cooling Panel for Residential Buildings, Integrated Into a Novel “Magnetic/PCM” Ground Coupled Flat Heat Pipe

2008 ◽  
Author(s):  
Gustavo Gutierrez ◽  
Josean Aponte
Keyword(s):  
Heat Pipe ◽  
Residential Buildings ◽  
Low Cost ◽  
Heat Pumps ◽  
Design Parameters ◽  
Working Fluid ◽  
Passive Cooling ◽  
Ground Source Heat Pumps ◽  
Reluctance Motor ◽  
Flat Heat Pipe

New perspectives for reducing heat and electricity consumption in building are emerging with innovative techniques such as highly insulating glazing and super insulated structures, utilization of solar energy, solar cells, hybrid ventilation solutions, energy efficient and demand-controlled ventilation, as well as integration of solutions, energy production in building. A relatively new innovation is the use of ground-source heat pumps that have become popular for both residential and commercial heating and cooling applications because of their higher energy efficiency compared to conventional systems. In this study, a flat heat pipe is proposed for using the enormous heat capacity of the soil as a heat sink to remove heat from the ambient, integrated the principal idea of a linear reluctance motor for the recirculation of the working fluid. Linear oscillating motors have a long history as rotary motors; but the complexity in the design and difficulties on their control limited the use of them. The motor consists of an iron bar, moving inside a coil. During the path of the iron bar an incremental force appears opposing the movement of the bar. For that reason, it is important to control the system and take advantage of that behavior. Reluctance motors can have high power density at a low cost, making them ideal for many applications. In this study, an implementation of the reluctance motor is proposed for using in a recirculation process of a passive cooling panel for residential buildings. Parametric studies are carried out to optimize the design parameters.

An Evaluation of the Wicking Characteristics of Stochastic Open-Cell Nickel Foams

2006 ◽  
Author(s):  
Jessica Sheehan ◽  
Douglas T. Queheillalt ◽  
Pamela M. Norris
Keyword(s):  
Pore Size ◽  
Heat Pipe ◽  
Friction Factor ◽  
Capillary Tube ◽  
Nickel Foam ◽  
Heat Pipes ◽  
Working Fluid ◽  
Open Cell ◽  
Pipe System ◽  
Nickel Foams

Heat pipes are a very efficient device which can be used for the rapid transfer of thermal energy. Small and microscale heat pipes are used in a variety of applications such as electronics and microprocessor coolers. As the size of the heat pipe devices increase, the volume and rate at which the working fluid is replenished in the evaporator region becomes an important parameter influencing the performance of the heat pipe system. Here, a stochastic open-cell nickel-foam has been evaluated for use as the wick material in heat pipes. The pore size of the open-cell nickel foam was modified via compression in the through thickness direction in order to evaluate its wicking characteristics and fluid flow resistance as a function of pore size. These properties are controlled by the effective pore size (controlled via through thickness compression) of the nickel foam. The equilibrium wicking height was measured by a simple flow experiment. The mass flow rate and the differential pressure of the crushed foams were measured at each thickness to generate a friction factor as a function of pore size. The equilibrium wicking height results were compared to a simple analytical model of a single capillary tube and found to be in reasonable agreement and the friction factor followed the same trend as the equilibrium wicking height. The experiments were used to evaluate the suitability of stochastic open cell nickel foams as wicks for heat pipe systems.

Passivation and Performance of Inorganic Aqueous Solutions in a Grooved, Aluminum Flat Heat Pipe

2013 ◽  
Author(s):  
Michael Stubblebine ◽  
Ladan Amouzegar ◽  
Ivan Catton
Keyword(s):  
Aqueous Solutions ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Hydrogen Gas ◽  
Working Fluid ◽  
Aerospace Applications ◽  
Heating Section ◽  
And Performance ◽  
Aluminum Plates ◽  
Flat Heat Pipe

Aluminum heat pipes have traditionally been incompatible with water and water-based fluids because they quickly react with the casing to generate non-condensable hydrogen gas (NCG). The NCGs inhibit the operation of evaporation and condensation based devices, eventually plugging the condenser end of the heat pipe. The heat pipe is then unable to remove heat from the condenser and the device fails. Terdtoon [1] found that these events often happen so rapidly between aluminum and water that measurements cannot even be taken. The present work tested two different, patented inorganic aqueous solutions (IAS) in a flat heat pipe setup. Grooved aluminum plates were used as the heat pipe wick and the tests were run with the heating section raised above the condenser. Compatibility between the working fluid and aluminum heat pipe was established by running the device to dryout and then reducing the heat flux to check for hysteresis. De-ionized water (DI water) was also tested, as a baseline, to establish that it did indeed fail as expected. Operating performance of each mixture was obtained from zero heat input until dryout was reached for multiple angles of inclination. The data show that both IAS mixtures are compatible with aluminum heat pipes and exhibit performance similar to that of a copper and water heat pipe. IAS and aluminum heat pipes could replace existing copper and water devices and deliver similar performance while reducing overall weight by more than three times. An IAS and aluminum heat pipe could also replace existing aluminum and ammonia combinations, currently favored in aerospace applications, to allow for increased performance and a larger operating temperature range while maintaining low device weight.

Comparison of Performance of Aluminum and Titanium Heat Pipes

2007 ◽  
Author(s):  
Gerardo Carbajal ◽  
G. P. Peterson ◽  
C. B. Sobhan
Keyword(s):  
Heat Pipe ◽  
Heat Input ◽  
Radiation Effects ◽  
Initial Conditions ◽  
Heat Pipes ◽  
Case Material ◽  
Working Fluid ◽  
Temperature Range ◽  
Short Period ◽  
Flat Heat Pipe

An investigation of the effect of using aluminum and titanium as the case material in a flat heat pipe (FHP) configuration is presented. In the heat pipe analyzed, the working fluid and the wick material were water and nickel foam, respectively. Identical configurations, dimensions, boundary and initial conditions were assumed in the numerical analysis for the two case materials. The flat heat pipe was subjected to a non-uniform heat input in the evaporator for a short period of time, and the condenser was cooled by natural convection and radiation effects. In both cases, non-uniform temperature distributions with peak values at the center of the evaporator side were observed. The titanium heat pipe gave a comparatively higher temperature range. The low thermal conductivity of titanium was understood to be responsible for the elevated temperature at the evaporator side. Consequently, it was also verified that for a low temperature range of operation and a short period of transient heat input, the aluminum heat pipe presented a better performance than the one with titanium as the case material. Discussions of the selection of the working fluids for the heat pipes based on the dimensionless merit number and other quantitative and qualitative parameters are also presented.

An Experimental Study on the Thermal Performance of the Flat Heat Pipe

2016 ◽  
Author(s):  
Hao Xiaohong ◽  
Jiqing Guan ◽  
Jingbo Zhao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Electronic Devices ◽  
Heat Pipes ◽  
Deionized Water ◽  
Working Fluid ◽  
Nano Fluid ◽  
Flat Heat Pipe

As the rapid growing of the semiconductor logic gate number and operation speed, the heat dissipated from electronic devices increases drastically. Moreover, most of the heat flux can reach about 100 W/cm2, therefore efficient removal of the heat from the electronic devices is essential to ensure the reliable operation of the electronic devices. The traditional direct cooling system, such as air cooling, liquid cooling, would not be able to transfer the high heat flux owing to their heat transfer limits, so advanced cooling solutions are necessary. The flat heat pipes have some advantages, such as small scale, strong heat transfer capacity, low weight penalty and low environmental requirements, therefore, in recent years, researchers have shown great interest for the flat heat pipe. But most of them played the important on the structure design of the flat heat pipes, and few of them focused on the study of the effect of the working fluid on the heat transfer performance. In this paper, a flat heat pipe with rectangular channel is designed and manufactured, and an experimental set up was built to study working fluid on the effects of the flat heat Pipe thermal performance. The flat heat pipe is heated via a 35mmx20mm rectangular electrical resistance (the evaporator side), and the other side (the condenser side) is cooled by convection of a heat sink. In the experimental work, three types of working fluid are used in the heat pipe: (A) deionized water, (B) deionized water-based Fe3O4 nano fluid (1, 1.5wt%). A comparison is performed for the thermal performance of different size flat heat pipe. Finally, the experimental results showed that nano fluid could improve the thermal performance of the FHP. With the same charge volume, the heat transfer coefficient of the FHPs filled with nano fluid were higher than that of DI water. There was an optimal mass concentration which was estimated to be 1.5 wt% to achieve the maximum heat transfer enhancement.

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