Effects of geometries on heat transfer enhancement of thermal fluids in curved ducts

The effects of geometries on multiplicity and stability of forced convection in curved ducts were analyzed in this study. A numerical study is made on the fully-developed forced convection in curved ducts of aspect ratio 1, 10 and curvature ratio 5 x 10(-6), 0.5 with Prandtl number of 7.0. Multiple solution branches are discovered for thermal fluids in curved ducts, and the bifurcation structure varies with curvature ratio and aspect ratio. More increase in heat transfer can be achieved with less increase in flow friction through switching the flow from one branch to another. It is found that the potentials of heat transfer enhancement in curved ducts with various aspect ratios and various curvature ratios are different. The flow stability varies in curved ducts with different aspect ratio and curvature ratio. (C) 2015 Elsevier Ltd. All rights reserved.