Heat transfer enhancement in microchannels with liquid - liquid slug flow using al2o3 nanoparticles

Abstract

Non–mixing two-phase flows in microchannels have become a popular technique for cooling applications due to their thermal performance and flow generation simplicity. Slugflow is one of the regimes in two-phase flow that has higher rates of heat and mass transfer in microchannels compared to other types because of the internal fluid recirculation within the slugs. The addition of nanoparticles to one of the phases in slug-flow could further increase the heat transfer rates. Therefore, in this research, nanofluid-based liquid-liquid slug-flow was studied. Studies were carried out numerically using ANSYS Fluent®. A series of studies were carried out to investigate the effect of nanoparticles on heat transfer. Aluminium oxide (Al 2 O 3 ) was selected as nanoparticles due to its physical and chemical stability along with its high thermal conductivity. Numerical results were validated with the experimental data available in the literature. Interface capturing of two-phase flow was done using VOF (Volume-of-Fluid) and Eulerian–Eulerian mixture models. The results showed a significant heat transfer enhancement when using nanoparticles in either phase. Two-phase slug-flow itself has shown up to four-times the increase in heat transfer in terms of Nusselt Number in the literature. This could be increased by more than eightfold by incorporating nanoparticles into the secondary phase.