Investigation of flow and heat transfer in a rectangular channel with discrete rib-mounted heat sources on two opposite walls

An experimental and theoretical investigation was carried out of the heat transfer and fluid flow in a rectangular channel in which two of its opposite walls (upper and lower walls) were provided with discrete ribs and heat sources., The two walls were equipped with uniform ally distributed ribs, each carrying flush-mounted heat source (a matrix 8x4), with each heater subjected to constant heat flux. This study was carried out on a channel of aspect ratio of 3.75:1 and over a Reynolds number range from 12000 to 40000. The rib is rectangular (5 mm x 3 mm) and fixed to one side of the heater element at right angle. The effects of ribs and interference of heat sources (some heater rows on, some heater rows off) on the heat transfer and fluid flow were studied. Cases of forward flow (rib facing flow first) and backward flow (heater facing flow first) through the channel were considered. A numerical solution was obtained by means of ``FLUENT version 6.26.3{''} computing package that adopts the (VF)-F-2 turbulence model. Experimental and numerical results comprised Nusselt number distributions, average Nusselt number and friction factor (f) for various Reynolds numbers. Results show a weak effect of the interference on flow characteristics in all cases. For heat transfer, the effect of interference was found weak or nonexistent in case of forward flow with ribs where as this effect was clear in case of the backward flow with ribs and the case of smooth (ribless) duct.