Numerical investigation on transient and steady phase change heat transfer in the evaporator of a loop heat pipe

Author(s):  
Qian SU ◽  
Shinan CHANG ◽  
Chen YANG
Author(s):  
Yasushi Koito ◽  
Hiroyuki Maehara ◽  
Toshio Tomimura

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.


2021 ◽  
Author(s):  
Alberto Mucci ◽  
Foster Kwame Kholi ◽  
June Kee Min ◽  
Man Yeong Ha ◽  
Jason Chetwynd-Chatwin

Author(s):  
Yasushi Koito ◽  
Hiroyuki Maehara ◽  
Daisuke Shimada ◽  
Toshio Tomimura

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.


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