Numerical analysis of heat transfer characteristics of combined electroosmotic and pressure-driven fully developed flow of power law nanofluids in microchannels

Abstract

Thermal transport characteristics of combined electroosmotic and pressur-driven flow of non-Newtonian (power-law) nanofluids through a microchannel have been studied. Non-Newtonian fluids can influence the thermal behaviour of the flow by affecting the rate of heat convection and viscous dissipation. Electroosmotic phenomenon causes resistance heating of the fluid, called Joule heating. Joule heating becomes a note-worthy phenomenon in microscale flow dynamics as the thickness of the ionic charged layer or electric double layer (EDL) is only about one-tenth to onehundredth of the channel height. Nanofluids are known to have better heat transfer characteristics than conventional fluids at microscale. A complete parametric study has been carried out to investigate the effect of different flow and electrolytic parameters on the thermal behaviour of the flow. The governing equations have been solved semianalytically under constant wall heat flux condition taking into account the effects of viscous dissipation and Joule heating. Power-law fluids of both shear-thinning and shear-thickening nature have been considered. The governing equations have been solved only for hydrodynamically and thermally fully-developed flow. Three nanofluidic parameters have been taken into consideration, namely: viscosity, electrical permittivity and electrical resistivity. These parameters have been introduced as ratios with reference to the corresponding properties of a conventional fluid.