NUMERICAL HEAT TRANSFER ENHANCEMENT IN SQUARE DUCT WITH INTERNAL RIB

This paper presents numerical investigation of heat transfer characteristics of horizontal square duct 500mm long using internal square-circle ribs of 7.5x7.5mm cross section ribs spacing =75mm, with air as the working fluid. Reynolds number= 34.267x103 was taken. The steel duct (ASM4120) was subjected to different constant surrounding hot air temperatures (673, 773 and 873Kº). Heat transfer was enhanced by (ΔT=9, 13 and 15Kº) for using ribs at constant surrounding air temperature of (673, 773 and 873Kº) respectively. Increases surrounding hot air temperature increases coolant air temperature at the duct centerline. Increases surrounding hot air temperature having no effect on coolant air velocity. Using ribs enhances fluctuation in coolant air velocity and thus enhances heat transfer rate. All studies where carried out using workbench program FlUENT14.5 by using K-ε model.