Enhanced heat transfer characteristics of the mini hexagonal tube heat sink using hybrid nanofluids

The thermal performance of different hybrid nanofluids on the mini hexagonal tube heat sink has been investigated experimentally. Al₂O₃/SiO₂-DIW, Al₂O₃/CuO-DIW, and CuO/SiO₂-DIW nanofluids have been used as the working fluids. The aggregate of 0.01 volume fraction of Al₂O₃, CuO, and SiO₂ nanoparticles for hybridizing ratios (80:20) has been considered to prepare deionized water-based hybrid nanofluids. The thermal performance of three different hybrid nanofluids inside the mini hexagonal tube heat sink has been assessed. The varying volumetric flow rates of 15-50 lph have been maintained on the hexagonal tube side and 50 lph on the mini passage side. Herein, the proposed hexagonal-shaped heat sink provides a larger heat contact surface to exchange the heat between the hybrid nanofluids and hot DIW. It is divulged that the increase in the volume flow rate of nanofluids promotes the higher Brownian motion, leading to an increase in convective heat transfer. Amongst three hybrid nanofluids, CuO/SiO₂-DIW nanofluids have revealed a slight increase in pumping power while increasing the volume flow rate. From the experimental results, it is shown that the heat transfer coefficient, effectiveness, and Nusselt number have been improved by 54.5%, 42%, and 28.4%, respectively, for Al₂O₃/CuO-DIW nanofluids. Thus, Al₂O₃/CuO-DIW nanofluid can be deemed to be an efficient working fluid for the miniature heat sinks to accelerate the heat transfer rates.