High Flux Value Micro-Heat Pipe Arrays

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001760-001807
Author(s):  
Daniel K. Harris ◽  
Robert Dean ◽  
Ashish Palkar ◽  
Gary Wonacott
Keyword(s):  
Liquid Metal ◽  
Heat Pipe ◽  
Experimental Work ◽  
Performance Enhancement ◽  
Performance Testing ◽  
Heat Pipes ◽  
Working Fluid ◽  
Working Fluids ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

The concept of heat pipes was introduced by R.S.Gaugler in 1940s and Cotter first introduced the idea of “micro” heat pipes in 1984. Cotter in his paper, defined the micro heat pipe as being one in which the mean curvature of the vapor-liquid interface is comparable in magnitude to the reciprocal of the hydraulic radius of the total flow channel. The Micro Heat Pipes (MHPs) work efficiently through the use of two-phase heat transfer. Various working fluids have been tried in combination with various substrate materials. In this experimental work the main focus was to study the behavior of liquid metal filled MHPs made from silicon as the substrate material. Specially designed MHPs were assembled and charged with mercury as the working fluid. A special test setup was designed and built for the experimental work and the response of the MHPs to the controlled increment in the input power is presented. A number of experiments were carried out on the specimen MHPs to determine their effective thermal conductivity, the variation of the temperature along the axial length and the performance enhancement factor. Effective thermal conductivities as high as 900 W/m-K with a silicon equivalence of 6 were achieved with the liquid metal MHP. Based on the results from the various performance testing parameters, it was observed that the liquid metal charged MHPs performed substantially better than conventional MHPs filled with organic working fluids. The limitations and the possible methods of improving the performance of the MHPs are discussed.

scholarly journals An investigation on effect of EDL on heat transfer of micro heat pipe with square and triangular cross section

2020 ◽  
Vol 21 (3) ◽  
pp. 309
Author(s):  
Maryam Fallah Abbasi ◽  
Hossein Shokouhmand ◽  
Morteza Khayat
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Double Layer ◽  
Electric Double Layer ◽  
Heat Pipes ◽  
The Body ◽  
Working Fluid ◽  
Two Phase ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

Electronic industries have always been trying to improve the efficiency of electronic devices with small dimensions through thermal management of this equipment, thus increasing the use of small thermal sinks. In this study micro heat pipes with triangular and square cross sections have been manufactured and tested. One of the main objectives is to obtain an understanding of micro heat pipes and their role in energy transmission with electrical double layer (EDL). Micro heat pipes are highly efficient heat transfer devices, which use the continuous evaporation/condensation of a suitable working fluid for two-phase heat transport in a closed system. Since the latent heat of vaporization is very large, heat pipes transport heat at small temperature difference, with high rates. Because of variety of advantage features these devices have found a number of applications both in space and terrestrial technologies. The theory of operation micro heat pipes with EDL is described and the micro heat pipe has been studied. The temperature distribution have achieved through five thermocouples installed on the body. Water and different solution mixture of water and ethanol have used to investigate effect of the electric double layer heat transfer. It was noticed that the electric double layer of ionized fluid has caused reduction of heat transfer.

Circulation Effectiveness of Working Fluid in Inclined Micro Heat Pipes

2015 ◽  
Vol 789-790 ◽  
pp. 422-425
Author(s):  
Fun Liang Chang ◽  
Yew Mun Hung
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Operating Conditions ◽  
Circulation Rate ◽  
Working Fluid ◽  
High Heat Flux ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

Micro heat pipe is a two-phase heat transfer device offering effective high heat-flux removal in electronics cooling. Essentially, micro heat pipe relies on the phase change processes, namely evaporation and condensation, and the circulation of working fluid to function as heat transfer equipment. The vast applications of micro heat pipe in portable appliances necessitate its functionality under different orientations with respect to gravity. Therefore, its thermal performance is strongly related to its orientation. By incorporating solid wall conduction, together with the continuity, momentum, and energy equations of the working fluid, a mathematical model is developed to investigate the heat and fluid flow characteristics of inclined micro heat pipes. We investigate both the favorable and adverse effects of gravity on the circulation rate which is intimately related to the thermal performance of micro heat pipes. The effects of gravity, through the angle of inclination, on the circulation strength and heat transport capacity are analysed. This study serves as a useful analytical tool in the micro heat pipe design and performance analysis, associated with different inclinations and operating conditions.

Steady-State Investigation of Vapor Deposited Micro Heat Pipe Arrays

1995 ◽  
Vol 117 (1) ◽  
pp. 75-81 ◽  
Author(s):  
A. K. Mallik ◽  
G. P. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Surface Temperature ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Heat Pipes ◽  
Temperature Gradients ◽  
Bottom Surface ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

An experimental investigation of vapor deposited micro heat pipe arrays was conducted using arrays of 34 and 66 micro heat pipes occupying 0.75 and 1.45 percent of the cross-sectional area, respectively. The performance of wafers containing the arrays was compared with that of a plain silicon wafer. All of the wafers had 8 × 8 mm thermofoil heaters located on the bottom surface to simulate the active devices in an actual application. The temperature distributions across the wafers were obtained using a Hughes Probeye TVS Infrared Thermal Imaging System and a standard VHS video recorder. For wafers containing arrays of 34 vapor deposited micro heat pipes, the steady-state experimental data indicated a reduction in the maximum surface temperature and temperature gradients of 24.4 and 27.4 percent, respectively, coupled with an improvement in the effective thermal conductivity of 41.7 percent. For wafers containing arrays of 66 vapor deposited micro heat pipes, the corresponding reductions in the surface temperature and temperature gradients were 29.0 and 41.7 percent, respectively, and the effective thermal conductivity increased 47.1 percent, for input heat fluxes of 4.70 W/cm2. The experimental results were compared with the results of a previously developed numerical model, which was shown to predict the temperature distribution with a high degree of accuracy, for wafers both with and without the heat pipe arrays.

Evaporation, Condensation, and Flow in an Idealized Micro Heat Pipe

2002 ◽  
Author(s):  
Jin Zhang ◽  
Harris Wong
Keyword(s):  
Thermal Conductivity ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Three Dimensional ◽  
Heat Pipes ◽  
Rigorous Analysis ◽  
Evaporation And Condensation ◽  
Micro Heat Pipe ◽  
Complicated Geometry ◽  
Micro Heat Pipes

Micro heat pipes have been used in cooling micro electronic components. However their effective thermal conductivity is low compared with that of conventional heat pipes. Due to the complexity of the coupled heat and mass transport, and to the complicated three-dimensional bubble geometry inside micro heat pipes, there is a lack of rigorous analysis. As a result, the relatively low effective thermal conductivity remains unexplained. We have conceptualized an idealized micro heat pipe that eliminates the complicated geometry, but retains the essential physics. Given the simplified geometry, many effects can be studied, such as thermocapillary flow, and evaporation and condensation physics. In this talk, we will present the flow field induced by evaporation.

Experimental Investigation of a New Flat Plate Solar Heat Collector by Micro Heat Pipe Array

2010 ◽  
Author(s):  
Yao-Hua Zhao ◽  
Fei-Long Zou ◽  
Yan-Hua Diao ◽  
Zhen-Hua Quan
Keyword(s):  
Flat Plate ◽  
Heat Pipe ◽  
High Efficiency ◽  
Heat Pipes ◽  
Total Heat Loss ◽  
Solar Heat ◽  
Solar Water ◽  
Micro Heat Pipe ◽  
Heat Collector ◽  
Micro Heat Pipes

The performance of a new flat plate solar heat collector with perfect combination of high efficiency and low cost is investigated experimentally. The new system described in this study uses a novel micro heat pipe array as a key component for the system. One such flat plate heat collector contains over 300 micro heat pipes per 1m2 and the hydraulic diameter of the micro heat pipes is 0.4–1.0mm. A detailed heat transfer experimental study is conducted during daylight hours over several months, focusing on the collector efficiency and overall efficiency of the system as well as total heat loss factor. The results show that the collector’s maximum instantaneous efficiency is up to 88%. Compared with conventional evacuated glass tube solar water heater, the system offers the additional benefits of high pressure resistance, low weight, good reliability and durability, easy integration into buildings and absence of freezing during winter months. Besides, compared with traditional flat-plate solar water system which is mainly sheet-and-tube concept, the system also shows many advantages: higher efficiency, much cheaper, absence of tube-bonding and freezing etc. Therefore, the system proposes a unique substitute to common solar water heating systems.

scholarly journals Experimental Set up of Two Closed Loop Pulsating Heat Pipe (CLPHP) with Water base Fluids

2019 ◽  
Vol 8 (12S) ◽  
pp. 715-719
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Heat Dissipation ◽  
Heat Pipes ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Water Mixture ◽  
Working Fluids ◽  
Pure Fluids ◽  
Acetone Water

Heat pipes are deliberated to be effective heat dissipation devices compared to other types of heat sinks due to their high effective thermal conductivity. Because of the flexibility in the design and layout of heat pipe turns along the heat source, pulsating heat pipes have gained popularity. One of the parameters that have the mainimpact on the presentation of CLPHP is the thermo physical properties of the working fluid. The properties of the working fluid affect the temperature difference between the evaporator and the condenser which in turn affect the thermal resistance of the CLPHP. In this connection, the influence of different working fluids is experimentally investigated on a two loop CLPHP, varying the evaporator heat flux. Pure fluids, viz., water, acetone, benzene and binary mixture, viz., Acetone-water and Benzene-water are utilized on working fluids. The heat input considered at the evaporator is 32W, 48W and 60W. The filling ratio is kept as 50 %. The results show that among the working fluids considered for the study, acetone exhibits least thermal resistance among the pure fluids at all heat fluxes considered in the analysis, while Acetone-water mixture has exhibited least thermal resistance among the water based mixtures.

Transient Response Characteristics of Vapor Deposited Micro Heat Pipe Arrays

1995 ◽  
Vol 117 (1) ◽  
pp. 82-87 ◽  
Author(s):  
G. P. Peterson ◽  
A. K. Mallik
Keyword(s):  
Heat Pipe ◽  
Time Constant ◽  
Imaging System ◽  
Heat Pipes ◽  
Silicon Wafers ◽  
Thermal Time ◽  
Transient Temperature ◽  
Micro Heat Pipe ◽  
Thermal Time Constant ◽  
Micro Heat Pipes

The transient thermal response of vapor deposited micro heat pipe arrays fabricated as an integral part of silicon wafers was measured to determine if these arrays could be used to reduce the local temperature gradients and improve the reliability of semiconductor devices. Wafers with arrays of 34 and 66 micro heat pipes were evaluated using an IR thermal imaging system in conjunction with a VHS video recorder. These arrays occupied 0.75 and 1.45 percent, of the wafer cross-sectional area, respectively. The wafers with micro heat pipe arrays demonstrated a 30 to 45 percent reduction in the thermal time constant when compared to that obtained for plain silicon wafers. This reduction in response time was shown to lead to a significant reduction in the maximum wafer temperature, due to the increased effective thermal conductivity caused by the vaporization and condensation occurring in the individual micro heat pipes. The experimental results were then used to validate a transient numerical model, capable of accurately predicting the transient temperature profile and thermal time constant of the wafer/heat pipe combinations.

Fabrication and Testing of SOG Structure Flat Heat Pipes with Triangle Grooves

2011 ◽  
Vol 483 ◽  
pp. 58-61 ◽  
Author(s):  
Xiao Wei Liu ◽  
Chao Wang ◽  
Tian Han ◽  
Tian Dong
Keyword(s):  
Thermal Conductivity ◽  
Heat Pipe ◽  
Glass Structure ◽  
Heat Pipes ◽  
Experimental Results ◽  
Working Fluid ◽  
Micro Heat Pipe ◽  
Vacuum Atmosphere

A new kind of charging and sealing method for SOG (silicon on glass) structure micro heat pipe with triangular grooves is investigated. MHP (micro heat pipe) is fully charged in a vacuum atmosphere which is useful for preventing air intermingle. Experimental results shows that when the fill ration of working fluid is about 35%, thermal conductivity of MHP with ethanol as its working fluid has an improvement of 19% compared to empty MHP.

An Experimental Investigation on Micro Heat Pipe with a Trapezium-Grooved Wick Structure

2010 ◽  
Vol 29-32 ◽  
pp. 1695-1700
Author(s):  
Shi Gang Wang ◽  
Xi Bing Li ◽  
Bai Rui Tao ◽  
Hong Xia Zhang
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Pipe ◽  
Optimum Design ◽  
Heat Pipes ◽  
Micro Heat Pipe ◽  
Capillary Limit ◽  
Heat Transfer Capacity ◽  
Wick Structure ◽  
Micro Heat Pipes

Through combination of experimental investigation with theoretical optimum design, this paper determined the crucial factors in affecting the heat transfer capacity in micro heat pipes with a trapezium-grooved wick structure are capillary limit and entrainment limit, and verified the validity of the heat transfer models thus built.

Overview of Micro Heat Pipe Research and Development

1992 ◽  
Vol 45 (5) ◽  
pp. 175-189 ◽  
Author(s):  
G. P. Peterson
Keyword(s):  
Research And Development ◽  
Heat Pipe ◽  
Historical Development ◽  
Heat Pipes ◽  
Experimental Investigations ◽  
Numerical Techniques ◽  
Fundamental Parameters ◽  
Micro Heat Pipe ◽  
Recent Advances ◽  
Micro Heat Pipes

The concept of a micro heat pipe was first proposed in 1984. Since that time, numerous analytical and experimental investigations have been conducted to determine the fundamental parameters that govern the operation of these devices. Micro heat pipes ranging in size from 1 mm in diameter and 60 mm in length to 30 μm in diameter and 10 mm in length have been analyzed, modelled, and fabricated. The following review describes the historical development of these devices, along with the analytical and numerical techniques used to model and predict their performance and the results of several recent experimental investigations. Because of recent advances in the development of micro heat pipes fabricated as an integral part of semiconductor wafers, particular emphasis has been placed on various construction and charging methods currently under investigation.

Sign in / Sign up

Export Citation Format

Share Document