Effects of turbulator shape, inclined magnetic field, and mixed convection nanofluid flow on thermal performance of micro-scale inclined forward-facing step

Abstract

This investigation numerically examined the combined impacts of different turbulator shapes, Al₂O₃/water nanofluid, and inclined magnetic field on the thermal behavior of micro-scale inclined forward-facing step (MSIFFS). The length and height for all turbulators were considered 0.0979 and 0.5 mm, respectively, and the Reynolds number varied from 5000 to 10000. In order to compare the skin friction coefficient (SFC) and the heat transfer rate (HTR) simultaneously, the thermal performance factor parameter (TPF) was selected. The results show that all considered cases equipped with turbulators were thermodynamically more advantageous over the simple MSIFFS. Besides, using Al₂O₃/water nanofluid with different nanoparticles volume fractions (NVF) in the presence of inclined magnetic field (IMF) increased HTR. With an increment of NVF from 1% to 4% and magnetic field density (MFD) from 0.002 to 0.008 T, HTR and subsequently TPF improved. The best result was observed for MSIFFS equipped with a trapezoidal-shaped turbulator with 4% Al₂O₃ in the presence of IMF (B=0.008 T). The TPF increased with the augmentation of Re, and the maximum value of it was 5.2366 for MSIFFS equipped with a trapezoidal-shaped turbulator with 4% Al₂O₃, B=0.008 T, and Re=10000.

Keywords

microchannel / forward-facing step / turbulator / inclined magnetic field / heat transfer enhancement

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