Turbulent Heat Transfer and Pressure Drop Characteristics of Dilute Water Based Al₂O₃–Cu Hybrid Nanofluids

A study on fully developed turbulent convective heat transfer and pressure drop characteristics of Al₂O₃–Cu/water hybrid nanofluid flowing through a uniformly heated circular tube is presented in this paper. For this, Al₂O₃–Cu nanocomposite powder was synthesized in a thermo chemical route using hydrogen reduction technique and dispersed the hybrid nano powder in deionised water to form a stable hybrid nanofluid of 0.1% volume concentration. The prepared powder was characterized by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) to confirm the chemical composition, determine the particle size and study the surface morphology. Stability of the nanofluid was ensured by pH and zeta potential measurements. The average heat transfer enhancement for Al₂O₃–Cu/water hybrid nanofluid is 8.02% when compared to pure water. The experimental results also showed that 0.1% Al₂O₃–Cu/water hybrid nanofluids have slightly higher friction factor compared to 0.1% Al₂O₃/water nanofluid. The empirical correlations proposed for Nusselt number and friction factor were well agreed with the experimental data.