Experimental and numerical investigation of convection heat transfer in a circular copper tube using graphene oxide nanofluid

To able to employ nanofluids in engineering applications, it is essential to investigate heat transfer properties in addition to thermophysical characteristics. In this work, the convection heat transfer coefficient of graphene oxide-distilled water nanofluid along a circular copper tube having a constant heat flux at the outside surface has been investigated both numerically and experimentally under turbulent flow regime. While the nanofluid convection heat transfer and head loss of pressure have been evaluated in the experimental section, the tube wall surface temperature, the convection heat transfer coefficient and friction factor have been obtained by using finite volume method in the numerical part with a three-dimensional domain by assuming single-phase flow. Surface and fluid temperatures and pressure drop of the distilled water have been acquired and compared with the related output from the correlation. Besides, the variations of the tube surface temperatures and the convection heat transfer coefficients of the nanofluids have been examined as numerical and experimental comparisons. The contours of the temperatures, convection heat transfer coefficients and pressure distributions for fluids have been presented. The convection heat transfer performances of the nanofluids according to the different volumetric flow rates, concentrations and the heat flux values have been exhibited in this study. The heat transfer coefficient increment value for the nanofluid of 0.02 vol% concentration and with a flow rate of 1.5 l/min (Re = 5032) has been obtained as about 48% for 5073.244 W/m 2 (350 W) heat flux according to the distilled water.