Abstract:
In this study, the convective mode heat transfer phenomena of bi-phase elasticoviscous
(non-Newtonian) nanofluid is quantified by forcefully flowing it through a specially designed
microchannel test section. The test section, which is rectangularly cross-sectioned and annexed
internally with cylindrical needle ribs is numerically investigated by considering the walls to be
maintained at a constant temperature, and to be susceptible to a magnetizing force field. The
governing system-state equations are numerically deciphered using control volume procedure and
SIMPLEC algorithm. With the Reynolds number (Re) varying in the turbulent range from 3000 to
11,000, the system-state equations are solved using the Eulerian–Eulerian monofluid Two-Phase
Model (TPM). For the purpose of achieving an apt geometry based on the best thermo-hydraulic
behavior, an optimization study must be mandatory. The geometry of the cylindrical rib consists
of h (10 × 10−3
, 15 × 10−3
, 20 × 10−3
), p (1.0, 1.5), and d (8 × 10−3
, 10 × 10−3
, 12 × 10−3
), which,
respectively, defines the height, pitch, and diameter of the obstacles, with the dimensions placed
within the braces being quantified in mm. The results demonstrated that the magnetic field leads to
an enhanced amount of average Nusselt number (Nuav) in contrast with the occurrence at B = 0.0.
This is due to the that the magnetic field pushes nanoparticles towards the bottom wall. It was found
that B = 0.5 T has the maximum heat transfer compared with the other magnetic fields. The channel
with h = 15 µm height leads to the maximum value of Nuav at all studied Re for constant values
of d and h. The channel with p = 1.5 µm results in the maximum value of Nuav at all studied Re
for constant values of d and h. The microchannel with d = 8 µm, p = 1.5 µm, and h = 15 µm in the
presence of the magnetic field with B = 0.5 T is the best geometry in the present work.
