Numerical investigation of heat transfer enhancement of a water/ethylene glycol mixture with Al2O3–TiO2 nanoparticles

摘要

This paper presents a numerical study of a four-component hybrid nanofluid consisting of binary nanoparticles, Al2O3 and TiO2, 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% Al2O3–1.5% TiO2 and 5% Al2O3–3% TiO2 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/m2 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 Al2O3–TiO2 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 Al2O3–TiO2 hybrid nanofluids with higher volume concentration.