Analysis of laminar mixed convection in inclined semicircular ducts under buoyancy-assisted and -opposed conditions

Several practical applications involve mixed convection in ducts of various cross sections and orientations. These applications include solar energy systems, cooling of electronic devices, compact heat exchangers, and cooling cores of nuclear reactors. Full understanding or the prevailing velocity and temperature fields, as well as the pressure drop and heat transfer characteristics, is necessary for the proper design of such systems. Here, laminate, fully developed mixed convection is inclined semicircular ducts is investigated theoretically under buoyancy-assisted and buoyancy-opposed conditions. A numerical, finite control volume approach was adopted in solving the governing equations, and results were obtained for the two limiting boundary conditions H1 and H2. These results include velocity and temperature distributions, a map for the onset of flow reversal, and data for the friction factor and Nusselt number. The results are presented with a detailed assessment of the effects of inclination, Reynolds number, Grashof number, and the thermal boundary conditions