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.

Fabrication of Heat Pipes on an Acrylic Resin Board

2013 ◽  
Author(s):  
Yasushi Koito ◽  
Hiroyuki Maehara ◽  
Toshio Tomimura
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phase Change ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Acrylic Resin ◽  
Working Fluid ◽  
Liquid Volume ◽  
Wiring Board ◽  
Phase Change Heat Transfer

As a first step to develop an electronic wiring board in which micro or miniature heat pipes are internally fabricated, the experimental and analytical studies are performed on a wickless gravity-assisted heat pipe, namely thermosyphon, fabricated on a surface of an acrylic resin board. This proposal aims at performing a phase-change heat transfer inside an electronic wiring board having a low thermal conductivity. In experiments, the evaporator section of the heat pipe is heated by a heater while the condenser section is water-cooled by a heat sink. Water is used as a working fluid. Changing a heat input and a liquid volume ratio inside the heat pipe, the temperature distribution is measured by thermocouples and then compared to the case where the working fluid is not charged. Moreover, the simple model of the heat pipe is made based on a thermal resistance network, and the analysis is performed on a phase-change heat transfer and a conductive heat transfer inside the resin board having the heat pipe. The effective thermal conductivity of the heat pipe is evaluated. Although this study is an initial stage, the operational and the heat transfer characteristics of the resin board having the heat pipe are confirmed.

A Capillary-Wick Heat Pipe Fabricated on a Plastic Board (Fundamental Experiments on Heat Transport Characteristics)

2015 ◽  
Author(s):  
Yasushi Koito ◽  
Hiroyuki Maehara ◽  
Daisuke Shimada ◽  
Toshio Tomimura
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phase Change ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Working Fluid ◽  
Experimental Investigations ◽  
Liquid Volume ◽  
Experimental Conditions ◽  
Phase Change Heat Transfer

A capillary-wick heat pipe having the dimensions of 5.0 mm × 5.0 mm × 100 mm (length) is fabricated on a surface of a plastic board, and the experimental investigations are conducted on the operational characteristics of the heat pipe. Plastics are easy to manufacturing, lightweight, low cost, flexible, and besides, the present study aims at the phase-change heat transfer inside the plastic board. A sintered copper powder and water are used as the wick structure and the working fluid of the heat pipe, respectively. In experiments, an evaporator section of the heat pipe is heated by a heater while a condenser section is water-cooled by a heat sink. A heat input and a liquid volume inside the heat pipe are changed, and the temperature distribution of the heat pipe is measured by thermocouples. Moreover, a one-dimensional thermal circuit model is made to evaluate the effective thermal conductivity of the heat pipe. From the experimental results, the continuous phase-change heat transfer inside the plastic board and its effectiveness are confirmed. It is also revealed that the effective thermal conductivity of the heat pipe is 854 W/(m·K) in maximum under the present experimental conditions.

scholarly journals Investigation of the Use of an Inorganic Aqueous Solution in Copper-Made Phase-Change Heat Transfer Devices

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Qi Yao ◽  
Jacob Supowit ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Aqueous Solution ◽  
Phase Change ◽  
Heat Transfer Performance ◽  
Capillary Rise ◽  
Copper Surface ◽  
Working Fluid ◽  
Transfer Performance ◽  
Phase Change Heat Transfer ◽  
Inorganic Aqueous Solution

A novel inorganic aqueous solution (IAS) is shown to have a better heat transfer performance than water when used as the working fluid in copper-made phase-change heat transfer devices. First, the physical properties of IAS are measured and compared to those of water. Another, a chemical analysis is performed, and the chemical reactions involved between IAS and the copper surface are listed and categorized by their contributions to the heat transfer performance. In addition, a capillary rise test is performed to show how each chemical contributes to the improvement of the surface wettability. Last, using IAS in copper-made phase-change heat transfer devices is discussed, and the main focus is how IAS improves the heat transfer performance by a smaller thermal resistance and a larger critical heat flux. The conclusion is validated by thermo-siphon tests at different inclination angles.

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.

A Novel Inorganic Aqueous Solution and its Effect on Liquid Spreading and Freeze/Thaw Processes

2013 ◽  
Author(s):  
Jacob Supowit ◽  
Sean Reilly ◽  
Ladan Amouzegar ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Aqueous Solution ◽  
Phase Change ◽  
Melting Process ◽  
Melting Rate ◽  
Working Fluid ◽  
Freeze Thaw ◽  
Liquid Spreading ◽  
Phase Change Heat Transfer ◽  
Inorganic Aqueous Solution

Frozen startup of phase change heat transfer devices is a complex problem that can have a large impact on heat transfer systems. A patented novel working fluid developed at UCLA comprised of an inorganic aqueous solution (IAS) was investigated for potential effects on the freeze/thaw capabilities in phase change heat transfer devices by examining the melting process of droplets. Preliminary visual tests were conducted to gain insight into any physical processes that surface augmentation created by this fluid may have on the freezing and melting process. These tests demonstrated significant differences in liquid spreading, the melting process, and the melting rate of droplets on surfaces pre-treated with IAS. Contact angle measurements exhibited enhanced wetting properties. SEM images of frozen droplets showed that liquid freezes in the small capillary wick formed by the initial evaporation of IAS. Video of melting droplets showed a significant increase in melting rate when the surface was first treated with IAS due to superior liquid spreading.

Performance of a Pulsating Heat Pipe Fabricated With a 3-D Printer

2017 ◽  
Author(s):  
Yasushi Koito ◽  
Masahiro Kawaji
Keyword(s):  
Heat Pipe ◽  
Two Phase Flow ◽  
Imaging System ◽  
Cooling Water ◽  
Working Fluid ◽  
Transient Temperature ◽  
Phase Flow ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Condenser Section

A pulsating heat pipe (PHP) was fabricated by a 3-D printer, and its heat transfer characteristics were investigated by experiments. A graphene-laden PLA (PolyLactic Acid) filament was used as a 3-D printing material. Ten square channels having a cross section of 1.5 mm × 1.5 mm and a length of 80 mm were made inside the PHP and the ends of channels were connected. Since the graphene-laden PLA filament allows electric currents to pass through, the 3-D printed PHP was electroplated by copper to maintain its airtightness. Ethanol was used as the working fluid. The 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 changed from 2.0 W to 8.0 W while the cooling water temperature and its flow rate were kept at 4.0 °C and 0.25 LPM, respectively. The transient temperature distribution of the PHP was measured by thermocouples. Moreover, because the graphene-laden PLA is nontransparent, an X-ray imaging system was also employed to observe the two-phase flow phenomena occurring in channels of the PHP. From the experimental results, the continuous heat transport from the evaporator to the condenser section of the PHP was confirmed with vapor-liquid two-phase flow characteristics observed inside the channels.

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.

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