This experimental paper analyzes the effects of auxiliary plate position along the centerline of a vertical channel on combined air natural convective and radiative heat transfer. These configurations can be found in the telecommunication systems and electronic cabinets with vertical cards.
The experiments are carried out by means of temperature measurements to obtain significant thermal parameters. A comparison between the different positions of the plate inside the channel is given in terms of channel wall temperatures. The results are given in terms of heated wall temperature profiles and radiative heat transfer for different thermal and geometrical parameters. Average Nusselt number as a function of the main thermal and geometrical parameters are presented and useful correlation equations are proposed. The comparison of the placement of the auxiliary plate, for high radiative heat transfer, shows that the auxiliary plate placed at the channel exit displays the lowest maximum channel wall temperatures when high Rayleigh numbers and heat flux values are considered. The configuration with this auxiliary plate placement is thoroughly examined for several h/L values and different emissivity coefficients. The channel aspect ratio, L/b, is equal to 10 and 20, the ratio of the auxiliary plate height to the channel one, h/L, 0, 0.25, 0.33 and 0.5, with emissivity coefficients of the walls equal to 0.1 and 0.9 and three different auxiliary plate positions inside the channel. The modified Rayleigh number values are in the 102–105 range.