Experimental Investigation of Al2O3-Polyethylene Glycol and TiO2-Polyethylene Glycol Nanofluids Flow through a Minichannel Heat Sink

Abstract

Heat dissipation becomes a significant issue in the performance of various heat transfer systems. Thermal properties of liquids decide its heat transfer performance. Conventional fluids have inherently poor thermal conductivity which makes them not suitable for high heat loads and heat fluxes. Nanofluids are proposed as a promising challenger for advanced heat transfer fluids in a variety of engineering applications. Nanofluids are colloidal suspensions of nanometer-sized particles in various base fluids. Nanoparticles will improve the heat transfer characteristics of the base fluids effectively. In the present work, the forced convective heat transfer performance of copper mini channel heat sink has been carried out experimentally using Al2O3 polyethylene glycol and TiO2 polyethylene glycol nanofluids. The Al2O3 and TiO2 are converted into nanoparticles by using planetary ball mill and its shape was analysed. The nano particles then dispersed in polyethylene glycol base fluid by using a magnetic stirrer to form nano fluid for different volume concentration 0.5%, 1%, 1.5%, 2%, 2.5% without adding surfactant. The thermo physical properties thermal conductivity, density, viscosity, boiling point, flash and fire point, pH value, the heat transfer rate, heat transfer coefficient, heat flux of Al2O3 polyethylene glycol and TiO2 polyethylene glycol based nanofluids is evaluated. The comparative heat transfer performance of these two types of nanofluids for different volume concentration is analysed by passing it at a constant inlet velocity of 0.058m/s through a square shape copper mini channel heat sink (30x30mm) with seven passages by maintaining at constant heat supply. Further by varying the heat input of the minichannel heat sink the heat transfer phenomenon of these two types of nanofluid is analysed. The experimental evaluation conform the effective enhancement of heat transfer characteristics in nanofluid by the influence of volume concentration. The results showed that the Al2O3 polyethylene glycol nanofluid thermal performance increased significantly and out performs the TiO2 polyethylene glycol nanofluid. The highest improvement in the heat transfer occurred was 26% for 2.5 volume% Al2O3 polyethylene glycol nanofluid when compared to TiO2 polyethylene glycol nanofluid.