Numerical Study of Water/Al2O3 Nanofluid Forced Convection in a Rotating Hydrophilic and Hydrophobic Microchannel

Abstract

In this work, water and water/Al2O3 nanofluid forced convection are studied numerically through a rotating U-shaped microchannel. The hydrophilic (no-slip flow) and hydrophobic (with slip length of 5 μm) conditions are used on the microchannel walls. Simulations are provided for various nanoparticle volume concentrations (ϕ=0-5%), and rotational speeds (ω =0-300 rad/s) and Reynolds numbers (Re=200-1000) to study their effects on the pressure drop, heat transfer, and thermal performance coefficient. A modified thermal performance criterion is suggested to include the variations of the working fluid properties relative to the reference case. It is observed that the existence of the nanoparticles in the base fluid provides considerable improvement on the heat transfer. The nanofluid flow also improves the thermal performance coefficient for volume concentrations of ϕ=0.5% and 2%, while it reduces for ϕ=5%. Although the thermal performance coefficient of the nanofluid flow at ϕ=5% decreases due to high pressure drop, but it is recommended to use water/Al2O3 at ϕ=5% as working fluid due to its high heat transfer enhancement (about 40%).

Keywords

• U-shaped rotating microchannel; Water/Al2O3 Nanofluid; Volume concentration; Hydrophobic
• slip length; Thermal performance.