scholarly journals A NUMERICAL ANALYSIS ON THE EFFECT OF DEVIATION FROM A CENTERED WICK STRUCTURE IN AN ULTRA-THIN FLATTENED HEAT PIPE

2021 ◽  
Vol 16 (0) ◽  
Author(s):  
Yasushi Koito
Keyword(s):  
Numerical Analysis ◽  
Heat Pipe ◽  
Wick Structure

Experimental and Numerical Analysis of Low-Temperature Heat Pipes With Multiple Heat Sources

1991 ◽  
Vol 113 (3) ◽  
pp. 728-734 ◽  
Author(s):  
A. Faghri ◽  
M. Buchko
Keyword(s):  
Numerical Analysis ◽  
Heat Pipe ◽  
Heat Load ◽  
Experimental Testing ◽  
Heat Pipes ◽  
Heat Sources ◽  
Wick Structure ◽  
Energy Equations ◽  
Vapor Region ◽  
Vapor Temperature

A numerical analysis and experimental verification of the effects of heat load distribution on the vapor temperature, wall temperature, and the heat transport capacity for heat pipes with multiple heat sources is presented. A numerical solution of the elliptic conjugate mass, momentum and energy equations in conjunction with the thermodynamic equilibrium relations and appropriate boundary conditions for the vapor region, wick structure, and the heat pipe wall are given. The experimental testing of a copper-water heat pipe with multiple heat sources was also made showing excellent agreement with the numerical results. An optimization of the heat distribution for such heat pipes was performed and it was concluded that by redistribution of the heat load, the heat capacity can be increased.

Design and Research of Flat Micro Heat Pipe with Glass Fiber Wick

2011 ◽  
Vol 483 ◽  
pp. 603-606
Author(s):  
Tian Han ◽  
Xiao Wei Liu ◽  
Chao Wang
Keyword(s):  
Glass Fiber ◽  
Heat Pipe ◽  
Experimental Testing ◽  
Governing Equations ◽  
Maximum Heat ◽  
One Dimensional ◽  
Micro Heat Pipe ◽  
Wick Structure

A kind of flat micro heat pipe with glass fiber wick structure is designed and fabricated. The structure of the wick is presented and also the excellence of the structure is described. For the glass fiber wick, the maximum heat transports is calculated by one-dimensional steady governing equations. Experimental testing is performed for the fabricated micro heat pipe in vacuum. The testing results is presented and analyzed.

Development and tests of loop heat pipe with multi-layer metal foams as wick structure

2016 ◽  
Vol 94 ◽  
pp. 324-330 ◽  
Author(s):  
Wei Zhou ◽  
Weisong Ling ◽  
Lian Duan ◽  
K.S. Hui ◽  
K.N. Hui
Keyword(s):  
Heat Pipe ◽  
Metal Foams ◽  
Loop Heat Pipe ◽  
Wick Structure

Novel Fluorescent Visualization Method to Characterize Transport Properties in Micro/Nano Heat Pipe Wick Structures

2009 ◽  
Author(s):  
Pramod Chamarthy ◽  
H. Peter J. de Bock ◽  
Boris Russ ◽  
Shakti Chauhan ◽  
Brian Rush ◽  
...  
Keyword(s):  
Heat Pipe ◽  
High Performance ◽  
Gravitational Force ◽  
Driving Forces ◽  
Electronics Cooling ◽  
Heat Pipes ◽  
High Permeability ◽  
Permeability Characteristics ◽  
Wick Structure ◽  
Initial Results

Heat pipes have been gaining a lot of popularity in electronics cooling applications due to their ease of operation, reliability, and high effective thermal conductivity. An important component of a heat pipe is the wick structure, which transports the condensate from condenser to evaporator. The design of wick structures is complicated by competing requirements to create high capillary driving forces and maintain high permeability. While generating large pore sizes will help achieve high permeability, it will significantly reduce the wick’s capillary performance. This study presents a novel experimental method to simultaneously measure capillary and permeability characteristics of the wick structures using fluorescent visualization. This technique will be used to study the effects of pore size and gravitational force on the flow-related properties of the wick structures. Initial results are presented on wick samples visually characterized from zero to nine g acceleration on a centrifuge. These results will provide a tool to understand the physics involved in transport through porous structures and help in the design of high performance heat pipes.

Numerical Analysis of the Phase-Change Heat Transfer Inside a Pulsating Heat Pipe With Overcritical Number of Turns

2020 ◽  
Author(s):  
Alberto Mucci ◽  
Foster Kwame Kholi ◽  
Man Yeong Ha ◽  
Jason Chetwynd-Chatwin ◽  
June Kee Min
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Heat Pipe ◽  
Gas Phase ◽  
Heat Pipes ◽  
Driving Mechanism ◽  
Small Range ◽  
Pulsating Heat Pipe ◽  
Prediction Ability ◽  
Semi Empirical

Abstract The Pulsating Heat Pipe (PHP) is a promising device in the family of heat pipes. With no need for a wick, they exhibit a high heat transfer to weight ratio. Moreover, the wickless design removes limits commonly associated with conventional heat pipes, increasing the maximum power transfer per single heat pipe. These peculiarities make it an ideal candidate for many high power applications. Nonetheless, there is though only partial knowledge on the driving mechanism, which restricts prediction accuracy. Most Pulsating Heat Pipe studies rely on experiments to test configurations, while simulations usually depend on semi-empirical correlations or adaptations of reduced theoretical models. Experiments provide detailed data for a particular geometry in lab fixed conditions, but it offers limited flexibility to test alternative configurations. Semi-empirical models use previous experimental data to create non-dimensional formulations. Though approaching an increased set of conditions, correlations apply with reasonable accuracy only to a small range, outside of which the prediction ability progressively falls. High order numerical analysis such as Computational Fluid Dynamics (CFD) modeling could potentially provide full visualization, but due to the complex flow behavior, previous studies used this method only in simple configurations with a small number of turns. The present research will expand the potential of this modeling technique by presenting the CFD analysis of a complex Pulsating Heat Pipe configuration. The importance of this study lies in the fact that this configuration, with a number of turns greater than a critical parameter, shows a reduced sensitivity to gravity and is therefore particularly important for applications where restrictions on installations make the positioning sub-optimal. The research simulates using a CFD commercial software a two-dimensional Pulsating Heat Pipe with sixteen turns. The heat pipe, with a 2 mm internal diameter, is filled with water at 50% of mass. To visualize the oscillation pattern of liquid and vapor slugs and plugs inside the Pulsating Heat Pipe, the model performs a transient analysis on the device. A Volume of Fluid (VOF) solver for multiphase analysis, coupled with the Lee model for evaporation and condensation mass transfer, calculates the interactions between the liquid and the gas phase inside the tube. The study follows the geometric and operational conditions from previous experiments. The analysis regards a Pulsating Heat Pipe operating in a vertical position with the condenser section placed in the upper sector. During the initial operations, the system flow distribution fluctuates between different flow modes as the fluid slugs and plugs structure forms. After stabilizing the heat transfer results well agree with the tested values. Moreover, the increased resolution allows us to fully visualize the internal operation, retrieving additional information on the temperature and ratio of liquid and gas phase along the heat pipe.

Experimental Investigation of the Miniature Loop Heat Pipe With Flat Evaporator

2005 ◽  
Author(s):  
Randeep Singh ◽  
Aliakbar Akbarzadeh ◽  
Masataka Mochizuki ◽  
Thang Nguyen ◽  
Vijit Wuttijumnong
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Thermal Control ◽  
Capillary Forces ◽  
High Heat ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Wick Structure ◽  
Flat Evaporator ◽  
Heat Loads

Loop heat pipe (LHP) is a very versatile heat transfer device that uses capillary forces developed in the wick structure and latent heat of evaporation of the working fluid to carry high heat loads over considerable distances. Robust behaviour and temperature control capabilities of this device has enable it to score an edge over the traditional heat pipes. In the past, LHPs has been invariably assessed for electronic cooling at large scale. As the size of the thermal footprint and available space is going down drastically, miniature size of the LHP has to be developed. In this paper, results of the investigation on the miniature LHP (mLHP) for thermal control of electronic devices with heat dissipation capacity of up to 70 W have been discussed. Copper mLHP with disk-shaped flat evaporator 30 mm in diameter and 10 mm thickness was developed. Flat evaporators are easy to attach to the heat source without any need of cylinder-plane-reducer saddle that creates additional thermal resistance in the case of cylindrical evaporators. Wick structure made from sintered nickel powder with pore size of 3–5 μm was able to provide adequate capillary forces for the continuos circulation of the working fluid, and successfully transport heat load at the required distance of 60 mm. Heat was transferred using 3 mm ID copper tube with vapour and liquid lines of 60 mm and 200 mm length respectively. mLHP showed very reliable start up at different heat loads and was able to achieve steady state without any symptoms of wick dry-out. Tests were conducted on the mLHP with evaporator and condenser at the same level. Total thermal resistance, R total of the mLHP came out to be in the range of 1–4°C/W. It is concluded from the outcomes of the investigation that mLHP with flat evaporator can be effectively used for the thermal control of the electronic equipments with restricted space and high heat flux chipsets.

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