Forced convective heat transfer enhancement of 90° bend plate-fin heat sink with grid generated turbulence

A. L. Teh, Y. W. Phoo, W. M. Chin, E. H. Ooi, J. J. Foo

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    Abstract

    This study numerically investigates the effects of grid-bars cross-sectional geometry and grid-fins arrangement to reshape the windward flow in promoting 90° bend plate-fin heat sink forced convection at Reynolds number 60.6 × 103. Three grid-bars cross-sections are proposed, namely: (i) reverse classic triangle (A), (ii) reverse flat-bottomed Reuleaux triangle (B), and (iii) reverse aerofoil (C), with regular grid of rectangular cross-section (G) as the control. The grid-fins configurations are structured as: (i) Inline-arranged regular grid (1), (ii) inline-arranged parallel grid (PG) (2), and (iii) staggered PG-fins (3). Results show that albeit the mild-decay in local-Nufin,L along the 90° bend, B2-grid gives the highest 57% overall system performance (a balance between Nufin and pressure coefficient) compared to the control without grid, interestingly, the G1 is −60%. Such achievement is attributed to the gradual curvature development along each bar that suppresses aerodynamic stall flow separation. The induced flow dynamic enables predominant channelling of air into fin separations. Most importantly, the vortex generation between the grid and fin strengthens the turbulence proximate to fin surface, hence enhances heat transfer. Overall, this study may shed light on the utilisation of B2-grid induced turbulence to promote an energy sustainable HVAC's 90° bend finned-tube heat exchanger forced convection.

    Original languageEnglish
    Pages (from-to)226-239
    Number of pages14
    JournalChemical Engineering Research and Design
    Volume156
    DOIs
    Publication statusPublished - Apr 2020

    Keywords

    • 90° bend plate-fin
    • Energy sustainability
    • Grid
    • HVAC
    • Thermal dissipation
    • Turbulence

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