Numerical Investigation of Heat Transfer to Fully Developed Turbulent Air Flow in a Concentric Pipe

Numerical simulation using standard k-e turbulence model was developed to investigate numerically the characteristic of backward-facing step flow in a concentric pipe. This research is focused on the surface temperature, local heat transfer coefficient and Nusselt number with the variation of Reynolds number and step height, in a fully developed turbulent air flow at room temperature. The design consists of entrance tube, inner and outer tubes at the test section. The inner tube is placed along the entrance tube at the test section with an outer tube to form annular passage. The entrance tube varies in diameter causing step height, s to vary (s= 0, 6 mm,14.5 mm and 18.5 mm). Reynolds number and heat flux were varied between 17050 and 44545 and 719 W/m² and 2098W/m² respectively. The results show that the higher Reynolds number and step height contribute to the enhancement of heat transfer. Lastly, with the advent of computational fluid dynamic software, fair and agreeable results were obtained for the present investigation.