Comparative assessment of numerical models for nanofluids' laminar forced convection in micro and mini channels

In the present study, laminar forced convection of Al2O3 + water and TiO2 + water nanofluids in the respective micro and mini channels has been investigated under constant heat flux boundary condition. The effectiveness of homogeneous, discrete phase model and Eulerian-Eulerian (Mixture, Volume of Fluid, Eulerian) models has been evaluated for experimental conditions reported by Karimzadehkhouei et al. (2015) and He et al. (2009). Hydrothermal characteristics of Al2O3 + water (dp=20nm) nanofluid have been studied for 0.25%, 0.5% and 2% particle volume fractions in Reynolds number range of 200-2000 whereas 0.24%, 0.6% and 1.18% particle volume fractions of TiO2 + water (dp=21nm) has been studied at 900 and 1500 Reynolds numbers. Results illustrate that for all nanoparticle volume fractions under consideration, discrete phase model (DPM) estimates most satisfactory hydrothermal results. For higher thermal conductive nanofluids, single phase model underestimates while Eulerian-Eulerian models over predict thermal fields. Though all the numerical models determine fairly analogous friction factor with respect to experimental as well as theoretical results.