Determining optimal formulations and operating conditions for Al2O3/water nanofluid flowing through a microchannel heat sink for cooling system purposes using statistical and optimization tools

Adding the proper nanoparticles to the fluid will result in the enhancement of transfer rate in a microchannel due to enhanced thermal conductivity of the working fluid, which inspired applying nanofluids in the small heat exchangers. This study aims to optimize the heat transfer characteristics of Al2O3/water nanofluid flowing in a microchannel for cooling system purposes. Three volume fractions of 0.1%-1% and nanofluid flow were considered in Reynolds numbers of 211-461. The goal was to obtain an optimum condition in terms of volume fraction and Reynolds numbers in order to have the lowest friction factor and the highest Nusselt number. Two distinctive mathematical correlations presented for Reynolds number and volume fraction to model the Nusselt number and friction factor of the nanofluid. First, the analysis of variance (ANOVA) introduced followed by determining models for non-dominated sorting genetic algorithm II (NSGA-II) which result in a multi-objective optimization condition. Furthermore, the optimum points for the nanofluid in each operating conditions were calculated. Finally, a couple of correlations among the calculated optimum points were proposed.