Evaluation of nanofluid performance with vortex generators for enhanced micro-channel heat transfer

This study explores the influence of nanofluids using various micro-channel geometries on conjugate heat transfer. The nanofluids used here, are SiO2 and Al2O3 nanoparticles with different concentrations up to 4% in water as a base fluid under laminar flow. A new design of a uniform micro-channel is considered, having different shapes of vortex generators (VGs) positioned at intervals along the base of the channel. After validation against previous micro-channel studies, numerical simulations with COMSOL Multiphysics® V5.2a are used to compare VGs having circular and elliptical cross-sections and fixed volume at Reynolds number 50-1000 with a uniform heat flux. The VGs are shown to offer significant potential in combatting the challenges of heat transfer in the technological drive toward lower weight/smaller volume electrical and electronic devices. The results show that non-dimensional factors (Re) can mislead the evaluation of heat transfer using nanofluid because Re is a function of the concentration and thermal properties, i. e. thermal conductivity, viscosity and density compared to the physical units such as the velocity.