Özet:

In this study, increment of convective heat transfer and pressure drop of graphene oxide (GO)-distilled water nanofluid with volumetric concentration of 0,01% in circular copper straight tubes having inner diameters of 12 mm and 16 mm, length of 1830 mm and with constant wall heat flux was experimentally investigated.  In addition, numerical calculations were performed as three-dimensional and steady by solving Navier-Stokes and energy equation using ANSYS-FLUENT program which is the finite volumes method with the assuming of single phase fluid. The effects of volumetric flow rate, heat flux and diameter of the tube were experimentally researched on the convective heat transfer coefficient and the pressure drop of the GO-distilled water nanofluid and the obtained values of convective heat transfer coefficient for the distilled water were compared with determined results from corresponding correlations. Results were presented as the variation of convective heat transfer coefficient and Nu number values at the values of different flow rates and heat fluxes for different tube diameters. And also, the variations of wall surface temperature and convective heat transfer coefficient values of the tubes were examined as numerical and experimental comparison. The obtained results showed that h and Nusselt number values of nanofluid increased with increasing of volumetric flow rate and heat flux and the highest increment values were reached at the pipe with 16 mm inner diameter. The increment value of average convective heat transfer coefficient of the GO-distilled water nanofluid was 34,88% at the flow rate of 1,5 L/min. (Re=1981) and the heat flux of 3043,94 W/m2 (350 W) for the tube with 16 mm inner diameter.

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