Thermal and hydrodynamic analysis of non-Newtonian nanofluid in wavy microchannel

Abstract

In this study, hydrodynamic and heat transfer of non-Newtonian nanofluid behavior is investigated in a wavy microchannel with rectangular obstacles. Aluminum oxide as nanoparticles (Al2O3) with 0.5% and 1.5% volume fractions and three different diameters (25, 45 and 100 nm) are added to pure water as a base phase to form a nanofluid structure. In order to form the non-Newtonian nanofluid, 0.5% carboxy methyl cellulose (CMC) is added to the nanofluid structure. Up and down walls of microchannels at the middle section where obstacles are located have constant 50,000 W⁄m2 heat flux. Inlet temperature is constant and equal to 298 K with different Reynolds numbers varying as 5, 50, 150 and 300. Rib heights varying between 3 and 7 μm for five cases with different nanoparticle volume fractions, nanoparticle diameters and Reynolds numbers are investigated. Nusselt number, friction factor and pressure drop are studied. Results indicated that the average Nusselt number is increased by increasing the volume fraction of Al2O3 nanoparticles. Also, the results show the largest friction factor value is obtained in the case with the highest obstacle height. It is observed that MC-3 case has maximum outlet temperature, and therefore is the best case among investigated cases.