Experimental investigation of thermal-rheological properties and heat transfer behavior of the heat transfer oil-copper oxide (HTO-CuO) nanofluid in smooth tubes

In this paper, thermophysical properties and convective heat transfer rate of the heat transfer oil-copper oxide nanofluid flow in horizontal smooth tubes is studied experimentally. At first, thermal-rheological characteristics of the heat transfer oil-copper oxide nanofluid, including density, volumetric thermal expansion coefficient, specific heat capacity, viscosity, and thermal conductivity, are measured at different temperatures. The heat transfer coefficient of HTO-CuO laminar flow under constant wall temperature boundary condition is also investigated. It is observed that the nanoparticle enhances the volumetric thermal expansion, viscosity, and thermal conductivity of the base fluid while decreases its specific heat. This behavior is also supported by some theoretical models. In addition, the Nusselt number is enhanced up to 32% using 1.5% CuO nanoparticles.