Heat Transfer and Friction Behaviors in Ribbed Rectangular Channel

Enhancing heat transfer surface are used in many engineering applications such as gas turbine blade cooling passages (i.e. channel/duct), air heater, heat exchanger surfaces, gas-cooled reactor fuel elements, ventilation equipment of microelectronic systems and air conditioning/ refrigeration systems, hence many techniques have been investigated on the enhancement of heat transfer rate and decrease the size and cost of the involving equipment especially in heat exchangers. One of the most important techniques used are passive heat transfer technique. These techniques when adopted in heat transfer surfaces proved that the overall thermal performance improved signi¿cantly. Rib roughness on the underside of the top wall of a duct has been found to substantially enhance the heat transfer coefficient. Surface roughness disturbs the laminar sub-layer in the turbulent flow and promotes local wall turbulence that, in turn, increases the heat transfer from the surfaces. The augmentation in heat transfer accompanies a higher pressure drop penalty of the fluid flow. A CFD investigation is conducted to study forced convection of fully developed turbulent flow in a rectangular ribbed duct.