An experimental study on the thermal and hydraulic performances of nanofluids flow in a miniature circular pin fin heat sink

• Thermal and hydraulic performances of nanofluids flowing in a miniature circular pin fin heat sink are reported.
• SiO2–water and ZnO–water nanofluids with concentrations of 0.2, 0.4 and 0.6 vol.% are investigated.
• The thermal performance of ZnO–water nanofluids is higher than the SiO2–water nanofluids around 3–9%.
• Particle types have no significant effect on the pressure drop or pumping power.
• New heat transfer and pressure drop correlations are proposed.

This study presents the experimental thermal and hydraulic performance of heat sink with miniature circular pin fin structure using two different types of nanofluid as coolant. ZnO and SiO2 nanoparticles dispersed in DI water with particle volume fraction of 0.2, 0.4 and 0.6 vol.% are tested and compared with the data for water. A heat sink with inline arrangement of circular pins is designed and made from aluminum material. The height, diameter, pitch, and number of pins are 1.2, 1.2, 2.4 mm and 143, respectively. Uniform heat flux at the bottom of the heat sink is performed. The present work is conducted at fluid temperature of 15 °C. The mass flow rate ranged from 0.65 to 3.32 kg/min and the heat flux ranged between 20 and 48 kW/m2. The effects of particle type, particle concentration, and mass flow rate on the thermal and hydraulic performances are reported. The measured data show that the heat transfer performance of the nanofluid-cooled heat sink is higher than that of the water-cooled heat sink. Comparison between ZnO and SiO2 nanofluids, higher heat transfer performance for ZnO–water nanofluids is observed by about 3–9%. For hydraulic performance, the results show that the addition of nanoparticles in the base fluid have a small effect on the pumping power. Finally, new heat transfer and pressure drop correlations are proposed to predict the Nusselt number and pressure drop of nanofluids flow in heat sinks with pin fin configuration.