Experimental investigation of diameter effect on heat transfer performance and pressure drop of TiO2–water nanofluid

In this paper, an experimental study performed to investigate the convection heat transfer characteristics in fully developed turbulent flow of TiO2–water nanofluid. The effect of mean diameter of nanoparticles on the convective heat transfer and pressure drop studied at nanoparticle volume concentration from 0.01 to 0.02 by volume. The experimental apparatus is a horizontal double tube counter-flow heat exchanger. The nanoparticles of TiO2 with diameters of 10, 20, 30 and 50 nm dispersed in distilled water as base fluid. The results indicated higher Nusselt number for all nanofluids compared to the base fluid. It is seen that the Nusselt number does not increase by decreasing the diameter of nanoparticles generally. In this study both Nusselt number and pressure drop were considered in definition of thermal performance factor. The results show that nanofluid with 20 nm particle size diameter has the highest thermal performance factor in the range of Reynolds number and volume concentrations were studied.

► It is an experimental study on Nu and pressure drop in turbulent flow of TiO2–water.
► It was focused on diameter effect of nanoparticle on Nu and pressure drop.
► This study done for 10–50 nm size diameter and 0.01–0.02 volume concentration.
► Both Nu and pressure drop were considered for finding the best thermal performance.
► The 20 nm particle size diameter has highest thermal performance than other diameter.