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Effects of pin fins and vortex generators on thermal performance in a microchannel with Al2O3 nanofluids

Wang, Jin LU ; Yu, Kai ; Ye, Mingzheng ; Wang, Enyu ; Wang, Wei LU and Sundén, Bengt LU (2022) In Energy 239.
Abstract

This paper performs a comparative analysis to obtain the optimal cross-section shape and parameters of both pin fins and vortex generators. A novel combined structure with pin fins and vortex generators is proposed to enhance thermal performance of an integrated microchannel heat sink. Effects of nanoparticle diameter and volume fraction are investigated using Al2O3 nanofluid and DI-water as working fluid. Pin fins and vortex generators cause enhancements of flow disturbance and heat transfer on microchannel heat sinks. Results indicate that oval pin fins have better improvements of thermal/hydraulic performance compared to round and diamond pin fins. The oval pin fin with 0.4 mm spacing and 0.1 mm height presents... (More)

This paper performs a comparative analysis to obtain the optimal cross-section shape and parameters of both pin fins and vortex generators. A novel combined structure with pin fins and vortex generators is proposed to enhance thermal performance of an integrated microchannel heat sink. Effects of nanoparticle diameter and volume fraction are investigated using Al2O3 nanofluid and DI-water as working fluid. Pin fins and vortex generators cause enhancements of flow disturbance and heat transfer on microchannel heat sinks. Results indicate that oval pin fins have better improvements of thermal/hydraulic performance compared to round and diamond pin fins. The oval pin fin with 0.4 mm spacing and 0.1 mm height presents the highest overall performance factor in the Reynolds number range of 340–640. Presence of vortices intensifies the mixing of the hot fluid near bottom surface and cold fluid near top surface. The optimal vortex generator with length of 0.08 mm and height of 0.06 mm provides a 30% increase in overall performance factor compared to the rectangular microchannel at Reynolds number of 340. Mechanism of heat transfer enhancement is analyzed by investigating flow velocity, temperature distribution and field synergy angle distribution in microchannels. Based on the field synergy principle, it is found that a small and uniformly distributed synergy angle is achieved in the integrated microchannel. According to comparisons of the overall performance factor and total thermal resistance, the optimal nanoparticle diameter and Al2O3 volume fraction of nanofluids are 20 nm and 4%, respectively.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Field synergy, Microchannel, Nanofluid, Pin fin, Vortex generator
in
Energy
volume
239
article number
122606
publisher
Elsevier
external identifiers
  • scopus:85119282051
ISSN
0360-5442
DOI
10.1016/j.energy.2021.122606
language
English
LU publication?
yes
id
4e85a8f0-aaec-4cc9-81fd-9e5905983fa8
date added to LUP
2021-12-13 14:31:28
date last changed
2023-11-09 01:50:22
@article{4e85a8f0-aaec-4cc9-81fd-9e5905983fa8,
  abstract     = {{<p>This paper performs a comparative analysis to obtain the optimal cross-section shape and parameters of both pin fins and vortex generators. A novel combined structure with pin fins and vortex generators is proposed to enhance thermal performance of an integrated microchannel heat sink. Effects of nanoparticle diameter and volume fraction are investigated using Al<sub>2</sub>O<sub>3</sub> nanofluid and DI-water as working fluid. Pin fins and vortex generators cause enhancements of flow disturbance and heat transfer on microchannel heat sinks. Results indicate that oval pin fins have better improvements of thermal/hydraulic performance compared to round and diamond pin fins. The oval pin fin with 0.4 mm spacing and 0.1 mm height presents the highest overall performance factor in the Reynolds number range of 340–640. Presence of vortices intensifies the mixing of the hot fluid near bottom surface and cold fluid near top surface. The optimal vortex generator with length of 0.08 mm and height of 0.06 mm provides a 30% increase in overall performance factor compared to the rectangular microchannel at Reynolds number of 340. Mechanism of heat transfer enhancement is analyzed by investigating flow velocity, temperature distribution and field synergy angle distribution in microchannels. Based on the field synergy principle, it is found that a small and uniformly distributed synergy angle is achieved in the integrated microchannel. According to comparisons of the overall performance factor and total thermal resistance, the optimal nanoparticle diameter and Al<sub>2</sub>O<sub>3</sub> volume fraction of nanofluids are 20 nm and 4%, respectively.</p>}},
  author       = {{Wang, Jin and Yu, Kai and Ye, Mingzheng and Wang, Enyu and Wang, Wei and Sundén, Bengt}},
  issn         = {{0360-5442}},
  keywords     = {{Field synergy; Microchannel; Nanofluid; Pin fin; Vortex generator}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Energy}},
  title        = {{Effects of pin fins and vortex generators on thermal performance in a microchannel with Al<sub>2</sub>O<sub>3</sub> nanofluids}},
  url          = {{http://dx.doi.org/10.1016/j.energy.2021.122606}},
  doi          = {{10.1016/j.energy.2021.122606}},
  volume       = {{239}},
  year         = {{2022}},
}