Investigation of non-Newtonian nano-fluid flow based on the first and second laws of thermodynamics by micro-annulus

In this study first and second law analyses of non-Newtonian nano-fluid flow through an annular cylinder filled with non-Newtonian water- CMC/TiO2 nano-fluid by considering temperature jump and slip velocity were investigated numerically. The single-phase was developed for heat transfer and nano-fluid flow. The impact of Reynolds number, nano-particles volume fraction, temperature jump, and slip velocity on Nusselt numbers and entropy generation were evaluated and the findings were discussed considering non-Newtonian performance of working fluid. The findings indicate that note the higher shear rate in the presence of the interior wall the Nusselt number for the interior wall was higher than outside walls. According to shear-thinning fluid behavior, when the flow has a higher shear rate, apparent viscosity would be small. So, it can be concluded that the apparent viscosity of flow close to the inner wall was low which decreased the impact of viscosity force and improved heat transfer due to convection-advection phenomena. In addition, the findings showed that the entropy generation ratio is very high at the entrance and it decreased along the annular tube. Furthermore, the apparent viscosity of fluid increases by nano-particle volume fraction.