Enhanced Heat Transfer Effectiveness Using Low Concentration SiO₂–TiO₂ Core–Shell Nanofluid in a Water/Ethylene Glycol Mixture

This paper assesses the heat transfer performance of nanofluids containing a core–shell structure of SiO₂ –TiO₂ 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 SiO₂ –TiO₂ nanoparticles were employed in a finned-tube cross-flow heat exchanger (automobile radiator kit). The obtained results indicate that SiO₂ –TiO₂ particles have an amorphous structure and make it possible to increase the thermal conductivity as the nanoparticle 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 SiO₂ –TiO₂ in a water/EG-based fluid.