Numerical study of conjugated heat transfer in a thick walled tube subjected to a nanofluid

In this paper, a numerical analysis is carried out to study the performance of conjugated convection-conduction heat transfer in a fin and thick-walled U-shaped tube heat exchanger subjected to a nanofluid. This geometry is mainly adopted for the aim of heating the chamber of Oghab Afshan bus (SCANIA). The problem is considered as two-dimensional, whereas the fins are treated as a one-dimensional conduction problem because of small thickness. So, the governing equations are derived based on the conceptual model in the Cartesian and polar coordinate systems for direct and bent paths, respectively. Then the governing equations have been approximated by means of a fully implicit finite volume control method (FVM). The effect of some geometrical variables and also the effect of applying various nanoparticles (a suspension of TiO ₃, Al ₂O ₃, and Cu nanoparticles in water) on the heat transfer and flow characteristic have been investigated. The results indicate that the lowest and greatest values of the Nusselt number are obtained for TiO ₃-water and Cu-water nanofluids, respectively.