Parametric Study of Nanoparticles Effects on Convective Heat Transfer of Nanofluids in a Heated Horizontal Annulus

This paper reports the results of a numerical study on the thermal performance of forced convection laminar flow of nanofluids flowing through a heated horizontal annular duct considering various nanoparticles types has been investigated. A numerical study is carried out for an annular duct filled with ordinary water, and three nanoparticles types of the titanium dioxide (TiO2), alumina (Al2O3) and copper (Cu) formed three different nanofluids. The outer cylinder is heated by a uniform and constant heat flux while the inner cylinder is thermally insulated. A numerical solution of the partial differential equations of dimensionless cylindrical coordinates associate with boundary conditions are discretized by the finite volume technique with a second order precision and solved via a FORTRAN program. Impacts of diverse parameters of the study such as nanoparticles volume fraction from 0 to 6% of titanium dioxide, alumina, copper, and Reynolds number on the thermal and hydrodynamic characteristic are examined. The axial and average Nusselt number increases with increasing nanoparticle concentration and Reynolds number. In addition, the skin friction coefficient decreases with increasing Reynolds number. Also, no significant effect on the skin friction coefficient with the increase in nanoparticle concentration. Furthermore, the improvement was seen higher when using nanofluids made of copper (Cu).