Experimental study of laminar flow forced-convection heat transfer in air flowing through offset plates heated by radiation heat flux

An experimental study of the steady state laminar flow forced-convection heat transfer of air flowing through offset plates located between two parallel plates and heated by radiation heat flux was carried out. The ranges of parameters tested were incident radiation heat fluxes of 500, 700, and 1000 W/m² . With Re ranging from 650 to 2560. the inlet air bulk temperatures changed from 18.2 to 70 °C and the tilting angel of the unit with the horizontal ranged from 0 to 90° respectively. The results show that the rate of the increase in the local Nusselt number was observed to be proportional with Re up to 1900, while it became less sensitive over Re range of 1900–2500. Also. in this range of Re, with the inlet air temperature of 20 °C, the angel of inclination of the unit has no effect on the local Nusselt number. Increasing the incident radiation heat flux in the case of higher values of Re leads to a slight decrease in the value of the local Nusselt number. The effect of the inlet air bulk temperature on the forced-convection heat transfer coefficient shows. in the case of the horizontal position. an increase in the inlet air bulk temperature leads to slight decreases in the value of the average Nusselt number. while it leads to a significant decreases in the value of the average Nusselt number as the tilting angle increases up to the vertical position. This effect is clearer in the case of Re = 650 rather than Re = 2550.