Plate-fin heat sink forced convective heat transfer augmentation with a fractal insert

Su Min Hoi, An Liang Teh, Ean Hin Ooi, Irene Mei Leng Chew, Ji Jinn Foo

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22 Citations (Scopus)

Abstract

The interaction of fractal grid-induced turbulence on plate-fin heat sink is numerically investigated at flow Reynolds number of ReDh = 7.3 × 104. Three fractal grids of different number of fractal iterations N, namely: The rectangular fractal grid of N = 2 (RFG2), square fractal grid of N = 3 (SFG3), and square fractal grid of N = 4 (SFG4)are employed to perturb the windward fluid flow. For each case, the effects of eight fractal grid first iterative bar thicknesses t0 at five different inter-fin distances δ are investigated. Results show that Nusselt number Nu and pressure drop ΔP increase with t0 for all cases. 57%, 51% and 43% of forced convective heat transfer augmentations are observed using SFG3, RFG2 and SFG4, respectively, than that of the control plate-fin heat sink. The thermal and fluid flow perturbation promoted by SFG3 outperforms the rest with Nu = 7.07 × 103 at δ = 10 and 25 mm, but at a cost of higher ΔP. RFG2's maximum Nu is 6.82 × 103 where wider δ of δ = 50 mm is preferred, and SFG4 is 6.42 × 103 at δ=10 mm. Interestingly, SFG4 enjoys a lower ΔP, which is highly energy sustainable. The strength of SFG3-induced turbulence intensity is able to infiltrate deeper into the fins at a higher flow rate, which may facilitate the continuous restructuring of inter-fin flow boundary layers, thus promoting thermal dissipation. In short, plate-fin heat sink forced convection is strongly dependent on the interaction between the insert configuration and the induced flow structures within fins, of which, the effects of t0 and δ are highly correlated.

Original languageEnglish
Pages (from-to)392-406
Number of pages15
JournalInternational Journal of Thermal Sciences
Volume142
DOIs
Publication statusPublished - Aug 2019

Keywords

  • CFD
  • Fractal geometry
  • HVAC
  • Plate-fin heat sink
  • Thermal dissipation
  • Turbulence

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