Numerical Investigation of Heat Transfer Enhancement of a Water/Ethylene Glycol Mixture with Al2O3-TiO2 Nanoparticles

This paper presents a numerical study of a four-component hybrid nanofluid consisting of binary nanoparticles, Al ₂O ₃ and TiO ₂, dispersed into a double base fluid mixture of water and ethylene glycol. The nanofluid were modeled as a single phase fluid with volume concentrations of 2.5% Al ₂O ₃–1.5% TiO ₂ and 5% Al ₂O ₃–3% TiO ₂ respectively. The nanoparticles are suspended in a double base fluid of water and ethylene glycol mixture with a 70:30 vol ratio. The simulations were conducted for turbulenct flow through a pipe at working temperatures of 293 K and varying Reynolds numbers (7800–2000). Constant heat flux of 129,983 W/m ² heat flux was applied to the pipe wall. The thermal conductivity was enhanced by 24% and 11% at concentrations of 5–3% and 2.5–1.5%, respectively. While, viscosity of hybrid nanofluids was rising up to 70% and 67% at the same concentration. The avarage heat transfer coefficient of Al ₂O ₃–TiO ₂ hybrid nanofluids were enhanced with increase of temperature and volume concentration. It was noted that the maximum heat transfer enhancement is 52% higher than the base fluid for a volume concentration of 5–3%. There is a slight increase in the friction factor of Al ₂O ₃–TiO ₂ hybrid nanofluids with higher volume concentration.