Experimental research on the performance of nanofluid flow through conically coiled tubes

In this paper, the thermal and hydrodynamic characteristics of SiO2 / water nanofluids flow through conically coiled tubes are examined experimentally. An experimental rig is constructed and set of experiments were carried out in order to investigate the heat transfer and pressure drop of SiO2-water nanofluids flow under constant wall heat flux condition through various conically coiled tubes. To better understand the fluid flow physics, the thermal conductivity and dynamic viscosity of nanofluids in different temperatures and volume fractions are measured experimentally. The results show that both heat transfer rate and pressure drop increase with increment in nanoparticle concentration. Moreover, the effects of cone angle and coil pitch were studied on heat transfer and pressure drop. Results indicate that, lower cone angle brings about more heat transfer and pressure drop. The maximum increase of 26% and 117% in heat transfer and pressure drop were recorded, respectively. Eventually, empirical correlations were presented for prediction of Nusslet number and friction factor in conically coiled tubes. (C) 2020 Elsevier B.V. All rights reserved.