Citation:
Abstract:
The aim of this study is to numerically examine the improvement techniques of the heat transfer in inclined tubes. The passive enhancement techniques are some of the most important means to improve heat transfer rates in engineering devices. In this research a passive enhancement technique (vortex generation) is combined with the tube inclination in order to improve heat transfer rates in solar concentrator absorber. Fins, acting as vortex generators, were attached to the internal wall of the tubes at different positions. A numerical simulation was performed using fluent software in which the finite volume method was used to solve the governing equations. The heat transfer rates obtained numerically were compared to those calculated using well known correlation (i.e. correlation of Shah and London) or others obtained experimentally. Through this study, it was found that the influence of fins on heat transfer rates is more important for the laminar regime than for the turbulent one for all considered inclinations. The optimal inclinations, which allow increasing the heat transfer, have also been determined for both laminar and turbulent flows. The findings of this research can be used to improve the heat transfer rates and therefore the efficiency of the solar concentrator absorber.