Experimental and numerical study on the thermal and hydrodynamic characteristics of non-Newtonian decaying swirl flows

Abstract

Experimental and numerical investigation has been carried out to determine the effectiveness of three novel inlet swirl flow generators on heat transfer of a non-Newtonian drilling nanofluid under turbulent flow conditions in a constant heat flux heat exchanger. Thermophysical and rheological properties of working fluid were measured and an empirical model for thermal conductivity was proposed. Non-Newtonian temperature dependent power law coefficients for drilling nanofluid were also presented. Experimental Nusselt number and friction factor were evaluated and compared to the numerical model results. Numerical Nusselt number and swirl number were used to predict thermal and hydrodynamic behavior of the flow at different Reynolds numbers from 4000 to 10,000. The outcomes demonstrate that the fluid flow and convective heat transfer are a function of nanofluid concentration, twist angle and Reynolds number. It also has been shown that the hydrodynamic and thermal characteristics of the flow are not necessarily similar in the whole domain.

Graphical Abstract

Keywords:

• Decaying swirl flow generator
• non-newtonian nanofluid
• nusselt number
• passive heat transfer enhancement
• pressure drop