Abstract
In this study, effects of thermal conduction in the wall on mixed convective heat transfer in a horizontal square duct are examined numerically. The working fluid is water. Two side walls and bottom wall in the heated section of the horizontal square duct are heated at a constant temperature (TW = 60°C), and fluid temperature at the entrance is 15°C. The upper wall of the heated section and all walls of the entrance section are constructed by acrylic plate. Numerical conditions are Re = 100 and Ri = 39.88, respectively. The SIMPLE procedure and QUICK scheme are employed to solve the governing equations through a control volume method. Obtained results have been compared with heat transfer and flow without the thermal conduction in the duct wall. The comparison indicates that the reverse flow appears near the upper wall. The reverse flow length on the heated section increases and approaches to an experimental result. Two recirculation flows on the side walls across the section move to the bottom wall, and the recirculation size on the bottom wall grows up. The spiral flow is generated in the duct and its spiral pitch increases. The position at which the local Nusselt number collapses moves downwards is compared with the case without the thermal conduction in the duct wall.
