Abstract:
This paper encapsulates results of a numerical investigation on flow and heat transfer of an incompressible medium with constant properties through an isothermal circular tube with alternating inclined ribs. Simulations are conducted for laminar, transitional, and turbulent flow regimes. As turbulence model, the transitional shear stress transport model is employed. The problem is investigated for four rib angle of attack values, as well as for a plain tube without any ribs. All configurations are observed to lead to a thermal performance factor close to or greater than unity. Within the investigated range, the larger thermal performance factors are observed to occur for the intermediate Reynolds numbers. Maximum values in the range 2.0-2.5 are predicted for the Reynolds number of 2,000, where a subsequent drop to values within the range 1.0-1.5 are found to occur for Reynolds numbers around 3,000-4,000, which may be attributed to the transitional effects.