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Enhancement of loop heat pipe performance with the application of micro/nano hybrid structures

Wang, Xueli LU ; Wei, Jinjia ; Deng, Yueping ; Wu, Zan LU and Sundén, Bengt LU (2018) In International Journal of Heat and Mass Transfer 127. p.1248-1263
Abstract

To further improve the flat-type loop heat pipe (LHP) performance, this study evaluates the practical potential of use of highly enhanced boiling structures. It is found that in our proposed new heat pipe (NHP) system, the working fluid from the evaporator outlet to the condenser inlet is in a liquid–vapor two phase flow, which is different from the classical LHP theory. A new P-T diagram is developed to better understand the thermal and hydraulic process during the NHP steady operation. In this study, by using the laser ablation technique two different types of micro- and nanoscale hybrid structures are synthesized on the boiling pool substrate. It is indicated that the formed valleys with a larger opening width play an important role... (More)

To further improve the flat-type loop heat pipe (LHP) performance, this study evaluates the practical potential of use of highly enhanced boiling structures. It is found that in our proposed new heat pipe (NHP) system, the working fluid from the evaporator outlet to the condenser inlet is in a liquid–vapor two phase flow, which is different from the classical LHP theory. A new P-T diagram is developed to better understand the thermal and hydraulic process during the NHP steady operation. In this study, by using the laser ablation technique two different types of micro- and nanoscale hybrid structures are synthesized on the boiling pool substrate. It is indicated that the formed valleys with a larger opening width play an important role in more effectively improving the bubble nucleation and bubble growth at the micrometer sites, which can subsequently lead to an increased number of active nucleation sites. The best loop performance is obtained with the micro-cone structured substrate at a heat load of 140 W, at which the maximum boiling pool heat transfer coefficient of 42.17 kW/m2·K is achieved. Compared with the polishing Cu substrate, it is enhanced by 110%. When maintaining the boiling pool temperature lower than 85 °C, the proposed new heat pipe system can tolerate a maximum heat flux of 35.12 W/cm2, which is larger than that of the most conventional LHPs with methanol as the working fluid.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Heat pipe performance enhancement, Heat transfer coefficient, Micro/nano hybrid structures, Thermal and hydraulic process, Thermal resistance
in
International Journal of Heat and Mass Transfer
volume
127
pages
16 pages
publisher
Pergamon
external identifiers
  • scopus:85049941622
ISSN
0017-9310
DOI
10.1016/j.ijheatmasstransfer.2018.06.138
language
English
LU publication?
yes
id
88fe9ee7-f398-41f2-a05d-724d9950018a
date added to LUP
2018-07-31 12:20:06
date last changed
2020-04-07 04:56:55
@article{88fe9ee7-f398-41f2-a05d-724d9950018a,
  abstract     = {<p>To further improve the flat-type loop heat pipe (LHP) performance, this study evaluates the practical potential of use of highly enhanced boiling structures. It is found that in our proposed new heat pipe (NHP) system, the working fluid from the evaporator outlet to the condenser inlet is in a liquid–vapor two phase flow, which is different from the classical LHP theory. A new P-T diagram is developed to better understand the thermal and hydraulic process during the NHP steady operation. In this study, by using the laser ablation technique two different types of micro- and nanoscale hybrid structures are synthesized on the boiling pool substrate. It is indicated that the formed valleys with a larger opening width play an important role in more effectively improving the bubble nucleation and bubble growth at the micrometer sites, which can subsequently lead to an increased number of active nucleation sites. The best loop performance is obtained with the micro-cone structured substrate at a heat load of 140 W, at which the maximum boiling pool heat transfer coefficient of 42.17 kW/m<sup>2</sup>·K is achieved. Compared with the polishing Cu substrate, it is enhanced by 110%. When maintaining the boiling pool temperature lower than 85 °C, the proposed new heat pipe system can tolerate a maximum heat flux of 35.12 W/cm<sup>2</sup>, which is larger than that of the most conventional LHPs with methanol as the working fluid.</p>},
  author       = {Wang, Xueli and Wei, Jinjia and Deng, Yueping and Wu, Zan and Sundén, Bengt},
  issn         = {0017-9310},
  language     = {eng},
  month        = {12},
  pages        = {1248--1263},
  publisher    = {Pergamon},
  series       = {International Journal of Heat and Mass Transfer},
  title        = {Enhancement of loop heat pipe performance with the application of micro/nano hybrid structures},
  url          = {http://dx.doi.org/10.1016/j.ijheatmasstransfer.2018.06.138},
  doi          = {10.1016/j.ijheatmasstransfer.2018.06.138},
  volume       = {127},
  year         = {2018},
}