A numerical study of water based Al2O3 and Al2O3–Cu hybrid nanofluid effect on forced convective heat transfer

•CFD modeling of hybrid nanofluid's effect on Nusselt number.•Good agreement between simulation results and experimental data.•Addition of nanoparticles enhance heat transfer coefficient.•Obtaining higher Nusselt number for hybrid nanofluid.•Represent two correlations for average Nu number & friction factor based on dimensionless numbers.

In this work, a CFD modeling of a horizontal circular tube was presented to investigate the effect of nanofluids on laminar forced convective heat transfer. The water-based Al2O3 and Al2O3–Cu hybrid nanofluid with 0.1% volume concentration and average particle size of 15 nm was considered. The solutions were based on both single- and two-phase approaches. The results showed a higher convective heat transfer coefficient for the hybrid nanofluid. In comparison to the single phase approach, the proposed mixture model revealed a better agreement with the experimental data. An energetic performance of fluid flowing was evaluated too. For these hybrid nanofluids, the average Nusselt number increase was 4.73% and 13.46% in compared to Al2O3/water and pure water, respectively.