Numerical investigation of heat transfer to fully developed turbulent air flow in a concentric pipe

Numerical simulation using standard k-e turbulencemodel was developed to investigate numerically thecharacteristic of backward-facing step flow in a concentricpipe. This research is focused on the surface temperature, localheat transfer coefficient and Nusselt number with the variationof Reynolds number and step height, in a fully developedturbulent air flow at room temperature. The design consists ofentrance tube, inner and outer tubes at the test section. Theinner tube is placed along the entrance tube at the test sectionwith an outer tube to form annular passage. The entrance tubevaries in diameter causing step height, s to vary (s= 0, 6 mm,14.5 mm and 18.5 mm). Reynolds number and heat flux werevaried between 17050 and 44545 and 719 W/m2 and 2098W/m2 respectively. The results show that the higher Reynoldsnumber and step height contribute to the enhancement of heattransfer. Lastly, with the advent of computational fluiddynamic software, fair and agreeable results were obtained forthe present investigation.