Heat Transfer Enhancement Using CuO Nanofluid in a Double Pipe U-Bend Heat Exchanger

The present research aims to enhance the convective heat transfer coefficient inside the tube of the double pipe heat exchangers, this is carried out by mixing the water with copper oxide (CuO) nanoparticles. In this study, the effects of nanofluid with different volume concentrations from 0 to 0.4%, flowrates of nanofluid inside the tube, and water flow through the annulus, and inlet temperature inside the tube were examined on the Nusselt number. From the analysis, experiential data found nanoparticles have a significant enhancement of the convective heat transfer coefficient inside the tube of the double pipe. The heat transfer coefficient inside the tube increases as the Reynolds numbers of the flow inside the tube, and water flow through the annulus increase. The convective heat transfer coefficients reached maximum values at 0.35% of the volume concentrations of CuO nanoparticles and then decreased as the increase of the volume concentrations increases. The fiction factor increases as the volume concentrations of nanoparticles increases. Empirical correlations are presented describing the Nusselt number and the friction factor of the nanofluid flow inside the tube of the double pipe and concealing the affecting parameters in such process.