Developing the Coaxial Dual-Pipe Heat Pipe for Applications on Heat Pipe Cooler

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Chen-Ching Ting ◽  
Chien-Chih Chen
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Cooling Water ◽  
Working Fluid ◽  
Observation Window ◽  
Condenser Section ◽  
Transfer Property ◽  
Heat Transfer Property ◽  
Adiabatic Section ◽  
Pipe Heat

This article presents significant experimental data about the coaxial dual-pipe heat pipe which is invented by our CCT laboratory. The coaxial dual-pipe heat pipe is built-in an inner pipe in the adiabatic section of a common heat pipe. A common heat pipe is composed of three sections: the evaporator section at the one end; the condenser section at the other end; and the adiabatic section in between. The vapor and the liquid phases of the working fluid flow in opposite directions through the core and the wick, respectively. This special heat transfer behavior causes a common heat pipe to yield the discrete heat transfer property. In process, the vapor directly brings large amounts of heat from heat source and rapidly flows through the adiabatic section to the condenser section. This intelligent heat transfer technique lets the heat pipe yield extremely large thermal conductivity. Unfortunately, a heat pipe integrated with cooling fin in the adiabatic section has changed its original heat transfer property. The integrated cooling fin in the adiabatic section has in advance taken heat of the vapor away and caused the vapor to be condensed in the adiabatic section. Therefore, the vapor cannot reach the condenser section and the condenser section hence loses its cooling capability. In other words, the effective cooling length of a common heat pipe which is integrated with cooling fin in the adiabatic section is shortened. The coaxial dual-pipe heat pipe is built-in an inner pipe in the adiabatic section of a common heat pipe to avoid heat of the vapor to be earlier taken away and even condensed in the adiabatic section. Experimental study in this work first built a home-made square coaxial dual-pipe heat pipe integrated with outside isothermal cycling cooling water as the coaxial dual-pipe heat pipe cooler. The home-made square coaxial dual-pipe heat pipe has an observation window. It is convenient to observe change of the two-phase flow inside the heat pipe influenced by the outside cooling water. The results show that the new developed coaxial dual-pipe heat pipe cooler has kept the original heat transfer property of the bare heat pipe. The vapor has reached the condenser section.

Developing the Coaxial Dual-Pipe Heat Pipe for Applications of Heat Pipe Cooler

2010 ◽  
Author(s):  
Chien-Chih Chen ◽  
Chen-Ching Ting
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Cooling Water ◽  
Observation Window ◽  
Two Phase ◽  
Transfer Property ◽  
Thermal Insulating ◽  
Copper Pipe ◽  
Heat Transfer Property ◽  
Pipe Heat

This article presents significant experimental data about the coaxial dual-pipe heat pipe which is new developed for applications of the heat pipe cooler in our CCT laboratory. It’s well known that heat pipe integrated with cooling plates has changed the heat transfer property of the heat pipe to be similar to copper pipe, where the heat transfer property of the bare heat pipe is discrete and the copper pipe is continuous. The integrated cooling plates cause the original heat transfer property of the heat pipe to be destroyed. For recovery of the original heat transfer property of the heat pipe in a heat pipe cooler, the coaxial dual-pipe heat pipe built a coaxial pipe inside the heat pipe in the thermal insulating section to avoid the heat of vapor being earlier taken away in the thermal insulating section. Experimental study in this work first built a home-made square coaxial dual-pipe heat pipe integrated with outside isothermal cycling cooling water. The home-made square coaxial dual-pipe heat pipe has an observation window and is convenient to observe the change of two-phase flow inside the heat pipe influenced by the outside cooling water. The results show that the new developed dual-pipe heat pipe cooler has kept the original heat transfer property of the bare heat pipe and therefore increases its cooling efficiency clearly.

scholarly journals Analyzing the Heat Transfer Property of Heat Pipe Influenced by Integrated Cooling Apparatus

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Chen-Ching Ting ◽  
Chien-Chih Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Pipe ◽  
Cooling Water ◽  
Cooling Power ◽  
Capillary Structure ◽  
Transfer Property ◽  
Face To Face ◽  
Heat Transfer Property ◽  
Circulating Cooling Water

Heat pipe with discrete heat transfer property is often called thermal superconductor because it has extremely large thermal conductivity. This special heat transfer property is destroyed by integrating cooling apparatus and further reducing the cooling power of a heat pipe cooler. This paper experimentally studied the heat transfer property of heat pipe influenced by integrated cooling apparatus. To simplify the investigating process, a home-made square heat pipe with the dimensions of L×W×H=10×10×100 mm3 was built with two pieces of copper plates and two pieces of glass plates face to face, respectively. The two pieces of copper plates were constructed with inside walls of capillary structure and the two pieces of glasses were with antifog inside walls for observing the inner phenomenon. Moreover, isothermal circulating cooling water was applied outside the heat pipe instead of cooling fin. The results show that heat vapor in the heat pipe is condensed earlier and cannot reach the remote section of condenser. In other words, the heat transfer property of heat pipe is destroyed by integrating cooling water. This phenomenon causes the unfavorable cooling power of the heat pipe cooler.

scholarly journals Sodium-Potassium Alloy Heat Pipe under Geyser Boiling Experimental Study: Heat Transfer Analysis

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7582
Author(s):  
Hongzhe Zhang ◽  
Fang Ye ◽  
Hang Guo ◽  
Xiaoke Yan
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heating Power ◽  
Heat Transfer Analysis ◽  
Working Fluid ◽  
Condenser Section ◽  
Sodium Potassium ◽  
Alloy Heat ◽  
Convection Cooling ◽  
Boiling Mode

In the geyser boiling mode, the working fluid state is divided into a boiling process and a quiet process, and the sodium-potassium (Na-K) alloy heat pipe can discontinuously transfer heat at each boiling. The overheating of the liquid working fluid at the bottom causes short-term boiling and forms slug bubble, the strong condensing ability quickly conducts heat from the evaporator section. And geyser boiling can occur before the working fluid forms continuous flow, so it transfers more heat at lower temperatures than natural convection cooling. In this study, the heat transfer process of a Na-K alloy heat pipe with forced convection cooling under different heating power was experimental studied. The geyser boiling mode can make the Na-K alloy heat pipe work below 650 °C and reduce the start-up time. In the process of geyser boiling, the heat transfer quantity was increased by the boiling frequency and the amount of vapor produced in a single boiling. The boiling temperature had no obvious change with the increased of heating power, and the condenser section temperature increased with the heating power.

Effect of Tube Bending on Heat Transfer Characteristics of Miniature Heat Pipe with Sintered Porous Media

2011 ◽  
Vol 312-315 ◽  
pp. 1015-1020 ◽  
Author(s):  
P. Sakulchangsatjatai ◽  
N. Thuchayapong ◽  
P. Terdtoon ◽  
N. Sangsirakoup
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Heat Pipe ◽  
Working Fluid ◽  
Tube Bending ◽  
Heat Transfer Characteristics ◽  
Small Space ◽  
Condenser Section ◽  
Transfer Characteristics ◽  
Evaporator Section

Miniature heat pipe is a compact heat transfer device with very high heat transfer capability. The miniature heat pipes have been widely accepted for thermal management in laptop computer. Generating heat from chip-set is rapidly transferred to a heat sink via the miniature heat pipe which occupies small space, resulting in smaller and more attractive size of the laptop. Heat pipe bending is unavoidable in such small space. However, tube bending decreases thermal performance of heat pipe and it stops working in some cases. In this study, a computer program to simulate heat transfer characteristics of a bending water-copper-sintered-wick heat pipe has been established. Domains of heat pipe consist of three parts; vapor of working fluid in vapor core which transfer heat and mass from evaporator section to condenser section, liquid of working fluid in wick which transfer heat and mass from condenser section to evaporator section in porous media by capillary force, and container wall. In simulation, fluid flow and heat transfer were assumed to be steady, laminar and incompressible. The porous media is saturated with liquid and working fluid is assumed to be Newtonian fluid. The governing equations, i.e. continuity, Navier-Stokes, and energy equations, and boundary conditions were solved by using the Finite Element Method (FEM). Several bending angles (0 and 90; angle measured from straight pipe) with 6 mm outer diameter and 200 mm length were simulated and tested. It was found that the predicted and experimental thermal resistances of heat pipe, when bending angle increases from 0 to 90, increased from 0.47°C/W to 0.65°C/W and 0.67°C/W to 0.88°C/W respectively, due to rising of the vapor pressure drop in vapor channel. The simulation results are in agreement with experimental data with 26-29% error.

scholarly journals Experimental Study of the Heat-Transfer Performance of an Extra-Long Gravity-Assisted Heat Pipe Aiming at Geothermal Heat Exploitation

2021 ◽  
Vol 13 (22) ◽  
pp. 12481
Author(s):  
Jiwen Cen ◽  
Feng Li ◽  
Tingliang Li ◽  
Wenbo Huang ◽  
Juanwen Chen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Water Flow Rate ◽  
Cooling Water ◽  
Filling Ratio ◽  
Working Fluid ◽  
Enhanced Geothermal Systems ◽  
Transfer Performance ◽  
Cooling Water Flow Rate

The installation and operation of enhanced geothermal systems (EGS) involves many challenges. These challenges include the high cost and high risk associated with the investment capital, potential large working-fluid leakage, corrosion of equipment, and subsiding land. A super-long heat pipe can be used for geothermal exploitation to avoid these problems. In this paper, a high aspect-ratio heat pipe (30 m long, 17 mm in inner diameter) is installed vertically. Experiments are then carried out to study its heat-transfer performance and characteristics using several filling ratios of deionized water, different heating powers, and various cooling-water flowrates. The results show that the optimal filling-ratio is about 40% of the volume of the vaporizing section of the heat pipe. Compared with a conventional short heat pipe, the extra-long heat pipe experiences significant thermal vibration. The oscillation frequency depends on the heating power and working-fluid filling ratio. With increasing cooling-water flow rate, the heat-transfer rate of the heat pipe increases before it reaches a plateau. In addition, we investigate the heat-transfer performance of the heat pipe for an extreme working-fluid filling ratio; the results indicate that the lower part of the heat pipe is filled with vapor, which reduces the heat-transfer to the top part. Based on the experimental data, guidelines for designing a heat pipe that can be really used for the exploitation of earth-deep geothermal energy are analyzed.

Copper Oxide (CuO) Effect on Heat Transfer Performance in an Oscillating Heat Pipe

2012 ◽  
Author(s):  
Yulong Ji ◽  
Chen Xu ◽  
Hongbin Ma
Keyword(s):  
Heat Transfer ◽  
Copper Oxide ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Inner Surface ◽  
Copper Tubing ◽  
Adiabatic Section

An experimental investigation of an oscillating heat pipe (OHP) with an inner surface coated with a copper oxide (CuO) layer was conducted. The OHP has six turns and three sections: evaporator, condenser and adiabatic section with the lengths of 40 mm, 64 mm and 51 mm, respectively. The cleaned copper tubing was chemically treated with a chemical solution and heated in a furnace. A layer of CuO was formed in the inner surface of the OHP. A working fluid (water in this study) at filling ratios ranging from 40% to 70% was studied. The experimental results show that the CuO layer can enhance the heat transfer performance of the OHP. The investigation results in a new way to enhance the heat transfer performance of an OHP.

The Particular Phenomenon of Pulsating Heat Pipe during its Operation Process

2011 ◽  
Vol 354-355 ◽  
pp. 1301-1304 ◽  
Author(s):  
Xun Wang ◽  
Xin Xin Mao ◽  
Lei Wang ◽  
Tong Han ◽  
Cheng Si Yang
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Pulsating Heat Pipe ◽  
Transfer Property ◽  
Experimental Data Processing ◽  
Fundamental Investigation ◽  
Operation Process ◽  
Heat Transfer Property

Combined with the existing research results, the heat transfer property of Pulsating Heat Pipe (PHP) was analyzed on the basis of experimental data processing in multi-operating conditions. PHP could self-repair when heat transfer was deteriorated, and the operating temperature continued to rise with the increased heating power during the operation. This study would contribute to the safe and effective operating; moreover, it could lay foundations for the fundamental investigation of PHP.

Fabrication of a Vapor Chamber on a Plastic Board

2015 ◽  
Author(s):  
Fumihiko Hideyama ◽  
Shuto Nonoshita ◽  
Yasushi Koito ◽  
Toshio Tomimura
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Low Cost ◽  
Cooling Water ◽  
Working Fluid ◽  
Liquid Volume ◽  
Transient Temperature ◽  
Vapor Chamber ◽  
Condenser Section ◽  
Phase Change Heat Transfer

A vapor chamber is a flat-plate heat pipe, where a cooled (condenser) section is much larger than a heated (evaporator) section, and has been used as a heat spreader to enhance the cooling of electronic devices. An objective of this study is to integrate the vapor chamber into a polycarbonate board. Plastic materials are easy to manufacturing, light weight, low cost, flexible, and then the present study aims at performing a phase-change heat transfer and a heat spreading inside the polycarbonate board. A sintered copper powder and water are used as a wick structure and a working fluid, respectively. In experiments, the heat is applied by a heater while the cooling water is circulated between a thermostatic bath and a cooling jacket. The experiments are conducted changing a liquid volume and a heat input, and the transient temperature distribution of the vapor chamber is measured by thermocouples. For comparison, the experiment is also conducted where the working fluid is not charged into the vapor chamber. Moreover, based on a thermal resistance network, an analytical model of the vapor chamber is made and the analysis is performed on the phase-change heat transfer inside the vapor chamber. From the experimental and analytical results, the heat transfer characteristics of the polymer-based vapor chamber and the effectiveness of the phase-change heat transfer are confirmed.

Heat Transfer Characteristics of a 3-D Printed Pulsating Heat Pipe: Fundamental Experiments Using Water As a Working Fluid

2017 ◽  
Author(s):  
Yasushi Koito ◽  
Masahiro Kawaji
Keyword(s):  
Heat Pipe ◽  
Cooling Water ◽  
Experimental Results ◽  
Working Fluid ◽  
Transient Temperature ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Condenser Section ◽  
Heater Power ◽  
Cooling Water Temperature

This paper describes extended experiments on a pulsating heat pipe (PHP) fabricated by using a 3-D printer and a graphene-laden PLA (PolyLactic Acid) filament. Water was used as a working fluid. To maintain airtightness, the 3-D printed PHP was electroplated by copper since the graphene in the filament allows electric currents to pass through. The PHP had ten square channels. A cross section and a length of the square channel were 1.5 mm × 1.5 mm and 80 mm, respectively. Ends of each channel were connected to form a single serpentine channel. A filling ratio of the working fluid was 50%. In experiments, an evaporator section of the PHP was heated by a heater and a condenser section was cooled using a water-cooling jacket. The heater power was increased stepwise from 2.0 W to 7.0 W while the cooling water temperature and its flow rate were maintained at 4.0 °C and 0.25 LPM, respectively. Transient temperature distributions of the PHP were measured by K-type thermocouples. From the experimental results, steady-state two-phase heat transport operation of the PHP was confirmed for the heater power between 3.0 W and 6.0 W. Moreover, the present experimental results were compared with the previous ones, where ethanol was used as the working fluid. It was also confirmed that the thermal resistance of the PHP with ethanol was slightly smaller than that with water.

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