Georg Schlindwein

A Comparative Study of Turbulence Models for Conjugate Heat Transfer to Gas Flow in a Heated Mini-Channel

Numerical simulations have been carried out for low Reynolds number (Re = 6000–10000) gaseous flows in a heated annular mini-channel using the commercial CFD codes CFX V12.0 and Star-CD V4.10. The results were compared with in-house experiments. Detailed comparisons were made between the low Reynolds number k-ϵ, k-ω-SST, and V2F of Star-CD and CFX in terms of numerical sensitivities and model performance. Particularly, it was found that the inlet turbulence conditions can have a significant impact on the simulation results in the downstream flow for Star-CD low-Re k-ϵ and V2F models. For heat transfer predictions, the Star-CD V2F model provides the best predictions under low Reynolds numbers of about 6,000, while for Reynolds numbers of about 10,000 the k-ω-SST model performs better than others.

Heat transfer and pressure drop measurements in channels roughened by variously shaped ribs on one wall

ABSTRACT Heat transfer and pressure drop measurements were conducted to study the thermal-hydraulics in a square, round-edged channel roughened by ribs (e/Dh = 0.0638, p/e = 10) on one wall at Reynolds numbers ranging from 5.0 × 104 to 2.5 × 105. Three variously shaped ribs were investigated: Transverse ribs with square cross sections, transverse ribs, and upstream directed 60° V-shaped ribs with round-edged rib front and rear surfaces. Friction factors, Nusselt number ratios, roughness functions, and the thermal performance were presented. The highest heat transfer and best thermal performance is reached by the upstream directed V-shaped ribs.