Numerical Analysis of Al₂ O₃ Nanofluid Based Slug Flow Heat Transfer in Microchannels

Microchannel-based cooling systems have turned out to be an efficient solution as they improve heat transfer due to the enhanced heat transfer surface area per unit volume. This research is focused on the nanofluid-based slug flow heat transfer in microchannels. The hydrodynamics and heat transfer performance of water-light mineral oil slug flow with alumina $\left(\mathrm{Al}_{2} \mathrm{O}_{3}\right)$ nanoparticles of 50 nm diameter, were numerically analyzed in microchannels using ANSYS Fluent software with the Eulerian mixture model as the multiphase model. The numerical results showed a decrease in the liquid film thickness by 8% when the volume concentration of nanoparticles was 1% in the primary phase. This has further decreased by 24% when the same amount of volume fraction is introduced to the secondary phase. Because of the nanoparticles presented in the secondary phase, internal circulation has considerably increased. It was identified that nanoparticle dispersion has a significant effect on the thermal conductivity and Nusselt number. A considerable increment in the local Nusselt number along the secondary phase droplets was observed compared to other regions in the flow. The bulk thermal conductivity of the slug flow has also increased due to the presence of nanoparticles.