Assessing heat transfer and nanofluid laminar flow in the curved micro-mixers by adopting two-phase model

Abstract

Micromixers are devices used for mixing fluids at the microscale level and are used for a variety of applications, including chemical reactions, mass transport, and heat transfer processes. In heat transfer processes, micromixers can enhance the heat transfer rate by creating a more homogeneous fluid mixture. In this research, the flow and heat transfer of a nanofluid are simulated in four different geometry of micromixers. The objective is to investigate which one has a better performance compared to a smooth microchannel with regard to the performance evaluation criterion (PEC), which proposes an evaluation with regard to the trade-off between heat transfer and pressure drop. For this purpose, the Ag/water nanofluid is simulated in micromixers of different geometries at Re numbers ranging from 200 to 800 and solid volume fractions (SVF) of 0, 2, and 4% using a finite volume method. The mixture model is adopted to simulate the nanofluid as a two-phase fluid, which is subjected to a laminar flow regime. The micromixers’ walls are exposed to constant heat flux. The effect of increasing the Re number and the SVF is assessed and compared in all geometries, and the results indicate that an increase in both these figures increases the PEC considerably. Moreover, the PEC for each case is assessed and compared, and the best and worst geometry in terms of heat transfer as well as pressure drop are presented. Specifically, in the best case with the highest PEC at the Re = 800 and SVF = 4%, the Nu number is increased by 2.3 fold while its pressure drop is increased by 1.42 fold compared to a smooth microchannel.