Thermofluidic characteristic of a nanofluid-cooled oblique fin heat sink: An experimental and numerical investigation

This paper presents an experimental and numerical investigation on the thermofluidic performance of 0.5-2.0 % of the volumetric concentration of Al2O3-water nanofluids through oblique fin heat sink microchannel (OFHS MC) in the Reynolds number range 100-300. In comparison, experiments were also performed using a straight channel heat sink microchannel (SCHS MC) of the same hydraulic diameter as the oblique fin channel. The fluid flow is simulated using the RNG k-epsilon model in both periodic and full domain numerical analysis. The phenomenological behaviour of the nanofluid flow is further studied using numerical results. The oblique fin microchannel encouraged the secondary flow, thus enhanced the macroscopic mixing. Boundary layer disruption and vortices generation in the secondary channel is the critical phenomena of improved heat transfer. A substantial improvement of heat transfer coefficient is achieved for nanofluid and oblique fin heat sink combinations compared to the straight channel heat sink. The heat transfer coefficient is increased at increasing nanofluid concentrations for any given Reynolds number and channel configuration. The enhancement of about 55 % in the heat transfer coefficient with a 2 % volumetric concentration of nanofluid is achieved at Re = 300 in an oblique fin heat sink. The heat transfer enhancement is always significant than the pressure penalty. The oblique fin heat sink improves the average junction temperature considerably compared to the straight channel heat sink. The inclusion of nanofluid can reduce the experimental junction temperature by up to 6 degrees C. Therefore, the combined advantage of the oblique fin heat sink with nanofluid is anticipated as one of the potential alternatives for electronics cooling.