ENHANCED HEAT TRANSFER EFFECTIVENESS USING LOW CONCENTRATION SiO_2-TiO_2 CORE-SHELL NANOFLUID IN A WATER/ETHYLENE GLYCOL MIXTURE

摘要

This paper assesses the heat transfer performance of nanofluids containing a core-shell structure of SiO_2-TiO_2 nanoparticles of low concentration in a mixture of water and ethylene glycol (EG) in a commercially available heat exchanger. For heat transfer analysis, 0-0.025% of SiO_2-TiO_2 nanoparticles were employed in a finned-tube cross-flow heat exchanger (automobile radiator kit). The obtained results indicate that SiO_2-TiO_2 particles have an amorphous structure and make it possible to increase the thermal conductivity as the nanoparticl fraction increases up to 0.04%. The nanofluid characteristics (Reynolds, Nusselt, and Prandtl numbers) increase, leading to an increase in the convection coefficient. As the thermal conductivity and the convection coefficient increase, the total heat transfer improves. Finally, the heat transfer effectiveness increases linearly by 21% with 0.025% mass fraction of SiO_2-TiO_2 in a water/EG-based fluid.